EP3526626A1 - Scanner laser à estimation d'égo-mouvement en ligne en temps réel - Google Patents

Scanner laser à estimation d'égo-mouvement en ligne en temps réel

Info

Publication number
EP3526626A1
EP3526626A1 EP17860192.8A EP17860192A EP3526626A1 EP 3526626 A1 EP3526626 A1 EP 3526626A1 EP 17860192 A EP17860192 A EP 17860192A EP 3526626 A1 EP3526626 A1 EP 3526626A1
Authority
EP
European Patent Office
Prior art keywords
points
data
scan
point cloud
laser
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP17860192.8A
Other languages
German (de)
English (en)
Other versions
EP3526626A4 (fr
Inventor
Ji Zhang
Sanjiv Singh
Kevin Joseph Dowling
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Kaarta Inc
Original Assignee
Kaarta Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from PCT/US2017/021120 external-priority patent/WO2017155970A1/fr
Application filed by Kaarta Inc filed Critical Kaarta Inc
Publication of EP3526626A1 publication Critical patent/EP3526626A1/fr
Publication of EP3526626A4 publication Critical patent/EP3526626A4/fr
Pending legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
    • G01S17/88—Lidar systems specially adapted for specific applications
    • G01S17/89—Lidar systems specially adapted for specific applications for mapping or imaging
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
    • G01S17/02—Systems using the reflection of electromagnetic waves other than radio waves
    • G01S17/06—Systems determining position data of a target
    • G01S17/42—Simultaneous measurement of distance and other co-ordinates
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
    • G01S17/66—Tracking systems using electromagnetic waves other than radio waves
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
    • G01S17/86—Combinations of lidar systems with systems other than lidar, radar or sonar, e.g. with direction finders
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
    • G01S7/4808—Evaluating distance, position or velocity data
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
    • G01S7/481—Constructional features, e.g. arrangements of optical elements
    • G01S7/4811—Constructional features, e.g. arrangements of optical elements common to transmitter and receiver
    • G01S7/4813—Housing arrangements
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
    • G01S7/51—Display arrangements
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
    • G01C21/00—Navigation; Navigational instruments not provided for in groups G01C1/00 - G01C19/00
    • G01C21/10—Navigation; Navigational instruments not provided for in groups G01C1/00 - G01C19/00 by using measurements of speed or acceleration
    • G01C21/12—Navigation; Navigational instruments not provided for in groups G01C1/00 - G01C19/00 by using measurements of speed or acceleration executed aboard the object being navigated; Dead reckoning
    • G01C21/16—Navigation; Navigational instruments not provided for in groups G01C1/00 - G01C19/00 by using measurements of speed or acceleration executed aboard the object being navigated; Dead reckoning by integrating acceleration or speed, i.e. inertial navigation
    • G01C21/165—Navigation; Navigational instruments not provided for in groups G01C1/00 - G01C19/00 by using measurements of speed or acceleration executed aboard the object being navigated; Dead reckoning by integrating acceleration or speed, i.e. inertial navigation combined with non-inertial navigation instruments
    • G01C21/1656—Navigation; Navigational instruments not provided for in groups G01C1/00 - G01C19/00 by using measurements of speed or acceleration executed aboard the object being navigated; Dead reckoning by integrating acceleration or speed, i.e. inertial navigation combined with non-inertial navigation instruments with passive imaging devices, e.g. cameras

Definitions

  • An autonomous moving device may require information regarding the terrain in which it operates. Such a device may either rely on a pre-defined map presenting the terrain and any obstacle that may be found therein. Alternatively, the device may have the capabilities to map its terrain while either stationary or in motion comprising a computer-based mapping system with one or more sensors to provide real-time data.
  • the mobile, computer-based mapping system may estimate changes in its position over time (an odometer) and/or generate a three- dimensional map representation, such as a point cloud, of a three-dimensional space.
  • Exemplary mapping systems may include a variety of sensors to provide data from which the map may be built. Some mapping systems may use a stereo camera system as one such sensor. These systems benefit from the baseline between the two cameras as a reference to determine scale of the motion estimation. A binocular system is preferred over a monocular system, as a monocular system may not be able to resolve the scale of the image without receiving data from additional sensors or making assumptions about the motion of the device.
  • RGB-D cameras have gained popularity in the research community. Such cameras may provide depth information associated with individual pixels and hence can help determine scale. However, some methods including the RGB-D camera may only use the image areas with coverage of depth information, which may result in large image areas being wasted especially in an open environment where depth can only be sparsely available.
  • an IMU may be coupled one or more cameras with, so that scale constraints may be provided from IMU accelerations.
  • a monocular camera may be tightly or loosely coupled to an IMU by means of a Kalman filter.
  • Other mapping systems may use optimization methods to solve for the motion of the mobile system.
  • mapping systems may include the use of laser scanners for motion estimation.
  • a difficulty of the use of such data may arise from the scanning rate of the laser. While the system is moving, laser points unlike a fixed position laser scanner are impacted by the relative movement of the scanner. Therefore the impact of this movement may be a factor of the laser points arriving arrive at the system at different times. Consequently, when the scanning rate is slow with respect to the motion of the mapping system, scan distortions may be present due to external motion of the laser.
  • the motion effect can be compensated by a laser itself but the compensation may require an independent motion model to provide the required corrections.
  • the motion may be modeled as a constant velocity or as a Gaussian process.
  • an IMU may provide the motion model.
  • Such a method matches spatio-temporal patches formed by laser point clouds to estimate sensor motion and correct IMU biases in off-line batch optimization.
  • GPS/INS techniques may be used to determine the position of a mobile mapping device.
  • high-accuracy GPS/INS solutions may be impractical when the application is GPS-denied, light-weight, or cost-sensitive. It is recognized that accurate GPS mapping requires line-of-sight communication between the GPS receiver and at least four GPS satellites (although five may be preferred). In some environments, it may be difficult to receive undistorted signals from four satellites, for example in urban environments that may include overpasses and other obstructions.
  • mapping device capable of acquiring optical mapping information and producing robust maps with reduced distortion.
  • a mapping system may include an inertial measurement unit, a camera unit, a laser scanning unit, and a computing system in communication with the inertial measurement unit, the camera unit, and the laser scanning unit.
  • the computing system may be composed of at least one processor, at least one primary memory unit, and at least one secondary memory unit.
  • the primary memory unit may store software that is executed by the at least one processor, in which the software may include: a first computational module that, when executed by the at least one processor, causes the at least one processor to compute first measurement predictions based on inertial measurement data from the inertial measurement unit at a first frequency; a second computational module that, when executed by the at least one processor, causes the at least one processor to compute second measurement predictions based on the first measurement predictions and visual measurement data from the camera unit at a second frequency; and a third computational module that, when executed by the at least one processor, causes the at least one processor to compute third measurement predictions based on the second measurement predictions and laser ranging data from the laser scanning unit at a third frequency.
  • the first computational module may further include software that, when executed by the at least one processor, causes the at least one processor to correct bias error in the first measurement predictions based on the second measurement predictions and the third measurement predictions.
  • the first frequency is greater than the second frequency and the second frequency is greater than the third frequency.
  • the second computational module may further include software that, when executed by the at least one processor, causes the at least one processor to determine whether the visual measurement data are degraded during a first measurement time period, and upon a determination that the visual measurement data are degraded during the first measurement time period, compute the second measurement predictions during the first measurement time period equal to first measurement predictions during the first measurement time period.
  • the third computational module may further include software that, when executed by the at least one processor, causes the at least one processor to determine whether the laser ranging data are degraded during a second measurement time period, and upon a determination that the laser ranging data are degraded during the second measurement time period, compute the third measurement predictions during the second measurement time period equal to second measurement predictions during the second measurement time period.
  • the primary memory device may store first and second sets of voxels in which the first and second sets of voxels are based on the third prediction measurements.
  • Each voxel of the first set of voxels may correspond to a first volume of space and each voxel of the second set of voxels may correspond to a second volume of space.
  • the second volume of space may be smaller than the first volume of space and each voxel of the first set of voxels may be mappable to a plurality of voxels of the second set of voxels.
  • the secondary memory unit may store point cloud data generated from the third prediction measurements.
  • the mapping system may further include a mobile unit, in which the inertial measurement unit is on the mobile unit, the camera unit is on the mobile unit, the laser scanning unit is on the mobile unit, and the computing system is on the mobile unit.
  • the mobile unit may include a navigation system for guiding the mobile unit and the navigation system may use the third measurement predictions to guide the autonomous mobile unit.
  • the third computation module may use a scan matching algorithm to compute the third measurement predictions.
  • the at least one processor may comprise multiple processing threads.
  • the primary memory device may store software that, when executed by the at least one processor, may manage the processing of scans of the laser ranging data by the multiple threads such that a first thread is assigned to scan match a first scan of the laser ranging data.
  • the first thread may be assigned to scan match a second scan of the laser ranging data from a point in time after the first scan, when the first thread can process the first scan before arrival of the second scan.
  • a second thread may be assigned to scan match the second scan of the laser ranging data when the first thread cannot process the first scan before arrival of the second scan.
  • the inertial measurement unit, camera unit and laser scanning unit may interface via the computing system with an interactive display on which a down-sampled version of the scanning data is presented in a three-dimensional representation.
  • a mapping system comprises an inertial measurement unit, a camera unit, a laser scanning unit, and a computing system in communication with the inertial measurement unit, the camera unit, and the laser scanning unit, wherein the computing system comprises at least one processor, at least one primary memory unit, and at least one secondary memory unit, wherein the primary memory unit stores software that is executed by the at least one processor, wherein the software comprises a first computational module that, when executed by the at least one processor, causes the at least one processor to compute at least one first measurement prediction based, at least on part, on inertial measurement data from the inertial measurement unit at a first frequency, a second computational module that, when executed by the at least one processor, causes the at least one processor to compute at least one second measurement prediction based, at least on part, on the at least one first measurement prediction and visual measurement data from the camera unit at a second frequency and a third computational module that, when executed by the at least one processor, causes the at least one processor to
  • the mapping system is comprised of a modularized system structure to address the problem of bidirectional information flow. Specifically, three modules address the problem step by step from coarse to fine data. Data processing flow may proceed from an IMU prediction module to a visual- inertial odometry module to a scan matching refinement module, while feedback flow occurs in a reverse order to correct the biases of the IMU.
  • the mapping system is dynamically reconfigurable. For example, if visual features are insufficient for the visual- inertial odometry, the IMU prediction module (partially) bypasses the visual-inertial odometry module to register laser points locally. If, on the other hand, environmental structures are insufficient for the scan matching, the visual-inertial odometry output (partially) bypasses the scan matching refinement module to register laser points on the map.
  • the mapping system employs priority feedback for IMU bias correction.
  • both the visual-inertial odometry module and the scan matching refinement module provide may feedback to the IMU prediction module to correct the IMU biases.
  • the feedback may be combined giving priority to the visual-inertial odometry module.
  • feedback from the scan matching refinement module compensates for the visual-inertial odometry module in directions where the visual-inertial odometry module is degraded.
  • the mapping system employs a two-layer voxel representation of the map.
  • the first layer is composed of large voxels. This layer is for map storage. For each large voxel that is close to the sensor, the voxel contains a second layer of small voxels for precisely retrieving the map for scan matching.
  • the mapping system employs multi-thread processing of scan matching.
  • the scan matching may utilize KD-tree building, point querying, matrix inverse for nonlinear optimization, and the like.
  • Standard parallel processing such as openMP can only accelerate point querying and does not serve to substantially reduce overall time.
  • the present system processes a different scan on each thread. In other words, the four threads process four consecutive scans instead of one scan.
  • a method comprises accessing a data set comprising a LIDAR acquired point cloud comprising a plurality of points each of which are attributed with at least a geospatial coordinate, sub-sampling at least a portion of the plurality of points to derive a representative sample of the plurality of points and displaying the representative sample of the plurality of points.
  • a method comprises acquiring a LIDAR point cloud comprising a plurality of points each of which are attributed with at least a geospatial coordinate and a segment, assigning a confidence level to each segment indicative of a computed accuracy of the plurality of points attributed with the same segment and displaying the assigned confidence levels to a user.
  • a method comprises acquiring a LIDAR point cloud with a SLAM system comprising a plurality of points each of which are attributed with at least a geospatial coordinate and a timestamp, displaying at least a portion of the plurality of points, receiving an indication of a specified time to which to rewind the acquisition of the point cloud and tagging a portion of the plurality of points each attributed with a timestamp after the specified time.
  • a method comprises acquiring a LIDAR point cloud with a SLAM system comprising a plurality of points each of which are attributed with at least a geospatial coordinate and a timestamp. displaying at least a portion of the plurality of points and displaying an indication to a user of a portion of the point cloud exhibiting a point density below a predetermined threshold.
  • FIG. 1 illustrates a block diagram of an embodiment of a mapping system.
  • FIG. 2 illustrates an embodiment a block diagram of the three computational modules and their respective feedback features of the mapping system of FIG. 1.
  • FIG. 3 illustrates an embodiment of a Kalmann filter model for refining positional information into a map.
  • FIG. 4 illustrates an embodiment of a factor graph optimization model for refining positional information into a map.
  • FIG. 5 illustrates an embodiment of a visual-inertial odometry subsystem.
  • FIG. 6 illustrates an embodiment of a scan matching subsystem.
  • FIG. 7A illustrates an embodiment of a large area map having coarse detail resolution.
  • FIG. 7B illustrates an embodiment of a small area map having fine detail resolution.
  • FIG. 8A illustrates an embodiment of multi-thread scan matching.
  • FIG. 8B illustrates an embodiment of single-thread scan matching.
  • FIG. 9A illustrates an embodiment of a block diagram of the three computational modules in which feedback data from the visual-inertial odometry unit is suppressed due to data degradation.
  • FIG. 9B illustrates an embodiment of the three computational modules in which feedback data from the scan matching unit is suppressed due to data degradation.
  • FIG. 10 illustrates an embodiment of the three computational modules in which feedback data from the visual-inertial odometry unit and the scan matching unit are partially suppressed due to data degradation.
  • FIG. 11 illustrates an embodiment of estimated trajectories of a mobile mapping device.
  • FIG. 12 illustrates bidirectional information flow according to an exemplary and non- limiting embodiment.
  • FIGS. 13a and 13b illustrate a dynamically reconfigurable system according to an exemplary and non-limiting embodiment.
  • FIG. 14 illustrates priority feedback for IMU bias correction according to an exemplary and non-limiting embodiment.
  • FIGS. 15a and 15b illustrate a two-layer voxel representation of a map according to an exemplary and non-limiting embodiment.
  • FIGS. 16a and 16b illustrate multi-thread processing of scan matching according to an exemplary and non-limiting embodiment.
  • FIGS. 17a and 17b illustrate exemplary and non-limiting embodiments of a SLAM system.
  • FIG. 18 illustrates an exemplary and non- limiting embodiment of a SLAM enclosure.
  • FIGS. 19a, 19b and 19c illustrate exemplary and non-limiting embodiments of a point cloud showing confidence levels.
  • FIG. 20 illustrates an exemplary and non-limiting embodiment of differing confidence level metrics.
  • FIG. 21 illustrates an exemplary and non- limiting embodiment of a SLAM system.
  • FIG. 22 illustrates an exemplary and non-limiting embodiment of timing signals for the SLAM system.
  • FIG. 23 illustrates an exemplary and non-limiting embodiment of timing signals for the SLAM system.
  • FIG. 24 illustrates an exemplary and non-limiting embodiment of SLAM system signal synchronization.
  • the present invention is directed to a mobile, computer-based mapping system that estimates changes in position over time (an odometer) and/or generates a three-dimensional map representation, such as a point cloud, of a three-dimensional space.
  • the mapping system may include, without limitation, a plurality of sensors including an inertial measurement unit (IMU), a camera, and/or a 3D laser scanner. It also may comprise a computer system, having at least one processor, in communication with the plurality of sensors, configured to process the outputs from the sensors in order to estimate the change in position of the system over time and/or generate the map representation of the surrounding environment.
  • IMU inertial measurement unit
  • 3D laser scanner 3D laser scanner
  • the mapping system may enable high-frequency, low-latency, on-line, real-time ego-motion estimation, along with dense, accurate 3D map registration.
  • Embodiments of the present disclosure may include a simultaneous location and mapping (SLAM) system.
  • the SLAM system may include a multi-dimensional (e.g., 3D) laser scanning and range measuring system that is GPS-independent and that provides real-time simultaneous location and mapping.
  • the SLAM system may generate and manage data for a very accurate point cloud that results from reflections of laser scanning from objects in an environment. Movements of any of the points in the point cloud are accurately tracked over time, so that the SLAM system can maintain precise understanding of its location and orientation as it travels through an environment, using the points in the point cloud as reference points for the location.
  • the resolution of the position and motion of the mobile mapping system may be sequentially refined in a series of coarse-to-fine updates.
  • discrete computational modules may be used to update the position and motion of the mobile mapping system from a coarse resolution having a rapid update rate, to a fine resolution having a slower update rate.
  • an IMU device may provide data to a first computational module to predict a motion or position of the mapping system at a high update rate.
  • a visual-inertial odometry system may provide data to a second computational module to improve the motion or position resolution of the mapping system at a lower update rate.
  • a laser scanner may provide data to a third computational, scan matching module to further refine the motion estimates and register maps at a still lower update rate.
  • data from a computational module configured to process fine positional and/or motion resolution data may be fed back to computational modules configured to process more coarse positional and/or motion resolution data.
  • the computational modules may incorporate fault tolerance to address issues of sensor degradation by automatically bypassing computational modules associated with sensors sourcing faulty, erroneous, incomplete, or non-existent data.
  • the mapping system may operate in the presence of highly dynamic motion as well as in dark, texture-less, and structure-less environments.
  • mapping system disclosed herein can operate in real-time and generate maps while in motion. This capability offers two practical advantages. First, users are not limited to scanners that are fixed on a tripod or other nonstationary mounting. Instead, the mapping system disclosed herein may be associated with a mobile device, thereby increasing the range of the environment that may be mapped in real-time. Second, the real-time feature can give users feedback for currently mapped areas while data are collected. The online generated maps can also assist robots or other devices for autonomous navigation and obstacle avoidance. In some non-limiting embodiments, such navigation capabilities may be incorporated into the mapping system itself. In alternative non-limiting embodiments, the map data may be provided to additional robots having navigation capabilities that may require an externally sourced map.
  • the mapping system can provide point cloud maps for other algorithms that take point clouds as input for further processing. Further, the mapping system can work both indoors and outdoors. Such embodiments do not require external lighting and can operate in darkness. Embodiments that have a camera can handle rapid motion, and can colorize laser point clouds with images from the camera, although external lighting may be required.
  • the SLAM system can build and maintain a point cloud in real time as a user is moving through an environment, such as when walking, biking, driving, flying, and combinations thereof. A map is constructed in real time as the mapper progresses through an environment. The SLAM system can track thousands of features as points.
  • the SLAM system operates in real time and without dependence on external location technologies, such as GPS.
  • a plurality (in most cases, a very large number) of features of an environment, such as objects, are used as points for triangulation, and the system performs and updates many location and orientation calculations in real time to maintain an accurate, current estimate of position and orientation as the SLAM system moves through an environment.
  • relative motion of features within the environment can be used to differentiate fixed features (such as walls, doors, windows, furniture, fixtures and the like) from moving features (such as people, vehicles, and other moving items), so that the fixed features can be used for position and orientation calculations.
  • Underwater SLAM systems may use blue-green lasers to reduce attenuation.
  • mapping system design follows an observation: drift in egomotion estimation has a lower frequency than a module's own frequency.
  • the three computational modules are therefore arranged in decreasing order of frequency.
  • High-frequency modules are specialized to handle aggressive motion, while low-frequency modules cancel drift for the previous modules.
  • the sequential processing also favors computation: modules in the front take less computation and execute at high frequencies, giving sufficient time to modules in the back for thorough processing.
  • the mapping system is therefore able to achieve a high level of accuracy while running online in real-time.
  • the system may be configured to handle sensor degradation. If the camera is non-functional (for example, due to darkness, dramatic lighting changes, or texture-less environments) or if the laser is non-functional (for example due to structure-less environments) the corresponding module may be bypassed and the rest of the system may be staggered to function reliably. The system was tested through a large number of experiments and results show that it can produce high accuracy over several kilometers of navigation and robustness with respect to environmental degradation and aggressive motion.
  • the modularized mapping system disclosed below, is configured to process data from range, vision, and inertial sensors for motion estimation and mapping by using a multi-layer optimization structure.
  • the modularized mapping system may achieve high accuracy, robustness, and low drift by incorporating features which may include:
  • mapping system for online ego-motion estimation with data from a 3D laser, a camera, and an IMU.
  • the estimated motion further registers laser points to build a map of the traversed environment.
  • ego-motion estimation and mapping must be conducted in real-time.
  • the map may be crucial for motion planning and obstacle avoidance, while the motion estimation is important for vehicle control and maneuver.
  • FIG 1 depicts a simplified block diagram of a mapping system 100 according to one embodiment of the present invention.
  • the illustrated system includes an IMU system 102 such as an Xsens® MTi-30 IMU, a camera system 104 such as an IDS® UI-1220SE monochrome camera, and a laser scanner 106 such as a Velodyne PUCKTM VLP-16 laser scanner.
  • IMU system 102 such as an Xsens® MTi-30 IMU
  • camera system 104 such as an IDS® UI-1220SE monochrome camera
  • a laser scanner 106 such as a Velodyne PUCKTM VLP-16 laser scanner.
  • the IMU 102 may provide inertial motion data derived from one or more of an x-y-z accelerometer, a roll-pitch-yaw gyroscope, and a magnetometer, and provide inertial data at a first frequency.
  • the first frequency may be about 200 Hz.
  • the camera system 104 may have a resolution of about 752x480 pixels, a 76° horizontal field of view (FOV), and a frame capture rate at a second frequency.
  • the frame capture rate may operate at a second frequency of about 50Hz.
  • the laser scanner 106 may have a 360° horizontal FOV, a 30° vertical FOV, and receive 0.3 million points/second at a third frequency representing the laser spinning rate.
  • the third frequency may be about 5Hz.
  • the laser scanner 106 may be connected to a motor 108 incorporating an encoder 109 to measure a motor rotation angle.
  • the laser motor encoder 109 may operate with a resolution of about 0.25° ⁇
  • the IMU 102, camera 104, laser scanner 106, and laser scanner motor encoder 109 may be in data communication with a computer system 110, which may be any computing device, having one or more processors 134 and associated memory 120, 160, having sufficient processing power and memory for performing the desired odometry and/or mapping.
  • a laptop computer with 2.6GHz i7 quad-core processor (2 threads on each core and 8 threads overall) and an integrated GPU memory could be used.
  • the computer system may have one or more types of primary or dynamic memory 120 such as RAM, and one or more types of secondary or storage memory 160 such as a hard disk or a flash ROM.
  • the mapping system 100 incorporates a computational model comprising individual computational modules that sequentially recover motion in a coarse-to- fine manner (see also FIG. 2).
  • a visual-inertial tightly coupled method (visual-inertial odometry module 126) estimates motion and registers laser points locally.
  • a scan matching method scan matching refinement module 132) further refines the estimated motion.
  • the scan matching refinement module 132 also registers point cloud data 165 to build a map (voxel map 134).
  • the map also may be used by the mapping system as part of an optional navigation system 136. It may be recognized that the navigation system 136 may be included as a computational module within the onboard computer system, the primary memory, or may comprise a separate system entirely.
  • each computational module may process data from one of each of the sensor systems.
  • the IMU prediction module 122 produces a coarse map from data derived from the IMU system 102
  • the visual-inertial odometry module 126 processes the more refined data from the camera system 104
  • the scan matching refinement module 132 processes the most fine-grained resolution data from the laser scanner 106 and the motor encoder 109.
  • each of the finer-grained resolution modules further process data presented from a coarser-grained module.
  • the visual-inertial odometry module 126 refines mapping data received from and calculated by the IMU prediction module 122.
  • the scan matching refinement module 132 further processes data presented by the visual inertial odometry module 126.
  • each of the sensor systems acquires data at a different rate.
  • the IMU 102 may update its data acquisition at a rate of about 200 Hz
  • the camera 104 may update its data acquisition at a rate of about 50 Hz
  • the laser scanner 106 may update its data acquisition at a rate of about 5 Hz.
  • These rates are non-limiting and may, for example, reflect the data acquisition rates of the respective sensors. It may be recognized that coarse-grained data may be acquired at a faster rate than more fine-grained data, and the coarse-grained data may also be processed at a faster rate than the fine-grained data.
  • specific frequency values for the data acquisition and processing by the various computation modules are disclosed above, neither the absolute frequencies nor their relative frequencies are limiting.
  • the mapping and/or navigational data may also be considered to comprise coarse level data and fine level data.
  • coarse positional data may be stored in a voxel map 134 that may be accessible by any of the computational modules 122, 126, 132.
  • File detailed mapping data, as point cloud data 165 that may be produced by the scan matching refinement module 132, may be stored via the processor 150 in a secondary memory 160, such as a hard drive, flash drive, or other more permanent memory.
  • both the visual-inertial odometry module 126 and the scan matching refinement module 132 can feed back their more refined mapping data to the IMU prediction module 122 via respective feedback paths 128 and 138 as a basis for updating the IMU position prediction.
  • coarse positional and mapping data may be sequentially refined in resolution, and the refined resolution data serve as feed-back references for the more coarse resolution computations.
  • FIG. 2 depicts a block diagram of the three computational modules along with their respective data paths.
  • the IMU prediction module 122 may receive IMU positional data 223 from the IMU (102, FIG. 1).
  • the visual-inertial odometry module 126 may receive the model data from the IMU prediction module 122 as well as visual data from one or more individually tracked visual features 227a, 227b from the camera (104, FIG. 1).
  • the laser scanner (106, FIG. 1) may produce data related to laser determined landmarks 233a, 233b, which may be supplied to the scan matching refinement module 132 in addition to the positional data supplied by the visual-inertial odometry module 126.
  • the positional estimation model from the visual-inertial odometry module 126 may be fed back 128 to refine the positional model calculated by the IMU prediction module 122.
  • the refined map data from the scan matching refinement module 132 may be fed back 138 to provide additional correction to the positional model calculated by the IMU prediction module 122.
  • the modularized mapping system may sequentially recover and refine motion related data in a coarse-to-fine manner.
  • the data processing of each module may be determined by the data acquisition and processing rate of each of the devices sourcing the data to the modules.
  • a visual-inertial tightly coupled method estimates motion and registers laser points locally.
  • a scan matching method further refines the estimated motion.
  • the scan matching refinement module may also register point clouds to build a map.
  • the mapping system is time optimized to process each refinement phase as data become available.
  • FIG. 3 illustrates a standard Kalman filter model based on data derived from the same sensor types as depicted in Figure 1.
  • the Kalman filter model updates positional and/or mapping data upon receipt of any data from any of the sensors regardless of the resolution capabilities of the data.
  • the positional information may be updated using the visual-inertial odometry data at any time such data become available regardless of the state of the positional information estimate based on the IMU data.
  • the Kalman filter model therefore does not take advantage of the relative resolution of each type of measurement.
  • FIG. 3 depicts a block diagram of a standard Kalman filter based method for optimizing positional data.
  • the Kalman filter updates a positional model 322a - 322n sequentially as data are presented.
  • the Kalman filter may predict 324a the subsequent positional model 322b. which may be refined based on the receive IMU mechanization data 323.
  • the positional prediction model may be updated 322b in response to the IMU mechanization data 323. in a prediction step 324a followed by update steps seeded with individual visual features or laser landmarks.
  • FIG. 4 depicts positional optimization based on a factor-graph method.
  • a pose of a mobile mapping system at a first time 410 may be updated upon receipt of data to a pose at a second time 420.
  • a factor-graph optimization model combines constraints from all sensors during each refinement calculation.
  • IMU data 323, feature data 327a, 327b, and similar from the camera, and laser landmark data 333a, 333b, and similar are all used for each update step. It may be appreciated that such a method increases the computational complexity for each positional refinement step due to the large amount of data required.
  • the sensors may provide data at independent rates that may differ by orders of magnitude, the entire refinement step is time bound to the data acquisition time for the slowest sensor.
  • FIGS. 1 and 2 sequentially recovers motion in a coarse-to-fine manner. In this manner, the degree of motion refinement is determined by the availability of each type of data.
  • a sensor system of a mobile mapping system may include a laser 106, a camera 104, and an IMU 102.
  • the camera may be modeled as a pinhole camera model for which the intrinsic parameters are known. The extrinsic parameters among all of the three sensors may be calibrated.
  • the relative pose between the camera and the laser and the relative pose between the laser and the IMU may be determined according to methods known in the art.
  • a single coordinate system may be used for the camera and the laser.
  • the camera coordinate system may be used, and all laser points may be projected into the camera coordinate system in pre-processing.
  • the IMU coordinate system may be parallel to the camera coordinate system and thus the IMU measurements may be rotationally corrected upon acquisition.
  • the coordinate systems may be defined as follows:
  • the camera coordinate system ⁇ C ⁇ may originate at the camera optical center, in which the x-axis points to the left, the -axis points upward, and the z-axis points forward coinciding with the camera principal axis;
  • the IMU coordinate system ⁇ 1 ⁇ may originate at the IMU measurement center, in which the x-, y-, and z- axes are parallel to ⁇ C ⁇ and pointing in the same directions;
  • ⁇ W ⁇ may be the coordinate system coinciding with ⁇ C ⁇ at the starting pose.
  • a state estimation problem can be formulated as a maximum a posterior (MAP) estimation problem.
  • MAP maximum a posterior
  • Z may be composed of both visual features and laser landmarks.
  • the joint probability of the system is defined as follows,
  • r X i and r z k are residual errors associated with the motion model and the landmark measurement model, respectively.
  • the standard way of solving Eq. 2 is to combine all sensor data, for example visual features, laser landmarks, and IMU measurements, into a large factor-graph optimization problem.
  • the proposed data processing pipeline instead, formulates multiple small optimization problems and solves the problems in a coarse-to-fine manner.
  • the optimization problem may be restated as:
  • ⁇ C ⁇ the fundamental sensor coordinate system
  • the IMU may also be characterized with respect to ⁇ C ⁇ .
  • ⁇ 1 ⁇ and ⁇ C ⁇ are parallel coordinate systems.
  • c ⁇ (t) and a(t) may be two 3 x 1 vectors indicating the angular rates and accelerations, respectively, of ⁇ C ⁇ at time t.
  • the corresponding biases may be denoted as b ⁇ (t) and ba(t) and n ⁇ (t) and n a (t) be the corresponding noises.
  • the vector, bias, and noise terms are defined in ⁇ C ⁇ .
  • g may be denoted as the constant gravity vector in ⁇ W ⁇ .
  • the IMU measurement terms are: where is the rotation matrix from ⁇ W ⁇ to ⁇ C ⁇ , and is the translation vector between
  • rotation center (origin of ⁇ C ⁇ ) is different from the origin of ⁇ / ⁇ .
  • Some examples of visual- inertial navigation methods model the motion in ⁇ 1 ⁇ to eliminate this centrifugal force term.
  • converting features without depth from ⁇ C ⁇ to ⁇ 1 ⁇ is not straight forward (see below).
  • the system disclosed herein models all of the motion in ⁇ C ⁇ instead. Practically, the camera and the IMU are mounted close to each other to maximally reduce effect of the term.
  • the IMU biases may be slowly changing variables. Consequently, the most recently updated biases are used for motion integration. First, Eq. 3 is integrated over time. Then, the resulting orientation is used with Eq. 4 for integration over time twice to obtain translation from the acceleration data.
  • the IMU bias correction can be made by feedback from either the camera or the laser (see 128, 138, respectively, in FIGS. 1 and 2). Each feedback term contains the estimated incremental motion over a short amount of time.
  • the biases may be modeled to be constant during the incremental motion.
  • b ⁇ (t) may be calculated by comparing the estimated orientation with IMU integration.
  • the updated b ⁇ (t) is used in one more round of integration to re-compute the translation, which is compared with the estimated translation to calculate ba(t).
  • a sliding window is employed keeping a known number of biases.
  • the number of biases used in the sliding window may include 200 to 1000 biases with a recommended number of 400 biases based on a 200Hz IMU rate.
  • a non- limiting example of the number of biases in the sliding window with an IMU rate of 100Hz is 100 to 500 with a typical value of 200 biases.
  • the averaged biases from the sliding window are used.
  • the length of the sliding window functions as a parameter for determining an update rate of the biases.
  • the disclosed implementation is used in order to keep the IMU processing module as a separate and distinct module.
  • the sliding window method may also allow for dynamic reconfiguration of the system.
  • the IMU can be coupled with either the camera, the laser, or both camera and laser as required. For example, if the camera is non-functional, the IMU biases may be corrected only by the laser instead.
  • a block system diagram of the visual-inertial odometry subsystem is depicted in Fig. 5.
  • An optimization module 510 uses pose constraints 512 from the IMU prediction module 520 along with camera constraints 515 based on optical feature data having or lacking depth information for motion estimation 550.
  • a depthmap registration module 545 may include depthmap registration and depth association of the tracked camera features 530 with depth information obtained from the laser points 540.
  • the depthmap registration module 545 may also incorporate motion estimation 550 obtained from a previous calculation.
  • the method tightly couples vision with an IMU.
  • Each provides constraints 512, 515, respectively, to an optimization module 510 that estimates incremental motion 550.
  • the method associates depth information to visual features as part of the depthmap registration module 545.
  • depth is obtained from laser points. Otherwise, depth is calculated from triangulation using the previously estimated motion sequence.
  • the method can also use features without any depth by formulating constraints in a different way. This is true for those features which do not have laser range coverage or cannot be triangulated because they are not tracked long enough or located in the direction of camera motion.
  • the visual-inertial odometry is a key-frame based method.
  • a new key-frame is determined 535 if more than a certain number of features lose tracking or the image overlap is below a certain ratio.
  • right superscript /, / ⁇ Z + may indicate the last key-frame
  • c, c ⁇ Z + and c > k may indicate the current frame.
  • the method combines features with and without depth.
  • a feature without depth is denoted as Y using normalized coordinates instead.
  • Xi, Xi, xi, and xi are different from ⁇ and x in Eq. l which represent the system state.
  • Features at key-frames may be associated with depth for two reasons: 1) depth association takes some amount of processing, and computing depth association only at key-frames may reduce computation intensity; and 2) the depthmap may not be available at frame c and thus laser points may not be registered since registration depends on an established depthmap.
  • a normalized feature in ⁇ C c ⁇ may be denoted as [0087] Let be the 3 x 3 rotation matrix and 3 x 1 translation vector between frames / and c, where form an SE(3) transformation. The motion
  • Xc has an unknown depth. Let d c be the depth, where Substituting X c with and combining the 1st and 2nd rows with the 3rd row in Eq. 5 to eliminate d c , results in
  • R(h) and t(h), h ⁇ ⁇ 1, 2, 3 ⁇ are the ⁇ -th rows of In the case that depth in unavailable to a feature, let di be the unknown depth at key-frame /. Substituting Xi and X c with respectively, and combining all three rows in Eq. 5 to eliminate dk and d c , results in another constraint,
  • the motion estimation process 510 is required to solve an optimization problem combining three sets of constraints: 1) from features with known depth as in Eqs. 6-7; 2) from features with unknown depth as in Eq. 8; and 3) from the IMU prediction 520.
  • the normalized term represents direction of the rotation and is the rotation angle. Each corresponds to a set of and containing 6-DOF motion of the camera.
  • a predicted transform between the last two frames c - 1 and c denoted as may be obtained from IMU mechanization.
  • IMU predicted translation is dependent on the orientation.
  • the orientation is dependent on the orientation.
  • accelerations that are integrated may be formulated as a function of and may be rewriten as It may be understood that the 200Hz pose provided by the IMU
  • the pose constraints fulfill the motion model and the camera constraints fulfill the landmark measurement model in Eq. 2.
  • the optimization problem may be solved by using the Newton gradient-descent method adapted to a robust fitting framework for outlier feature removal.
  • the state space contains and tf.
  • a full-scale MAP estimation is not performed, but is used only to solve a marginalized problem.
  • the landmark positions are not optimized, and thus only six unknowns in the state space are used, thereby keeping computation intensity low.
  • the method thus involves laser range measurements to provide precise depth information to features, warranting motion estimation accuracy. As a result, further optimization of the features' depth through a bundle adjustment may not be necessary.
  • the depthmap registration module 545 registers laser points on a depthmap using previously estimated motion.
  • Laser points 540 within the camera field of view are kept for a certain amount of time.
  • the depthmap is down-sampled to keep a constant density and stored in a 2D KD-tree for fast indexing.
  • KD-tree all laser points are projected onto a unit sphere around the camera center. A point is represented by its two angular coordinates.
  • features may be projected onto the sphere.
  • the three closest laser points are found on the sphere for each feature. Then, their validity may be by calculating distances among the three points in Cartesian space.
  • the depth is interpolated from the three points assuming a local planar patch in Cartesian space.
  • Those features without laser range coverage if they are tracked over a certain distance and not located in the direction of camera motion, may be triangulated using the image sequences where the features are tracked. In such a procedure, the depth may be updated at each frame based on a Bayesian probabilistic mode.
  • FIG. 6 depicts a block diagram of the scan matching subsystem.
  • the subsystem receives laser points 540 in a local point cloud and registers them 620 using provided odometry estimation 550. Then, geometric features are detected 640 from the point cloud and matched to the map. The scan matching minimizes the feature-to-map distances, similar to many methods known in the art.
  • the odometry estimation 550 also provides pose constraints 612 in the optimization 610.
  • the optimization comprises processing pose constraints with feature correspondences 615 that are found and further processed with laser constraints 617 to produce a device pose 650.
  • This pose 650 is processed through a map registration process 655 that facilitates finding the feature correspondences 615.
  • the implementation uses voxel representation of the map. Further, it can dynamically configure to run on one to multiple CPU threads in parallel.
  • the method When receiving laser scans, the method first registers points from a scan 620 into a common coordinate system. m, m E Z + may be used to indicate the scan number. It is understood that the camera coordinate system may be used for both the camera and the laser. Scan m may be associated with the camera coordinate system at the beginning of the scan, denoted as ⁇ C m ⁇ . To locally register 620 the laser points 540, the odometry estimation 550 from the visual-inertial odometry may be taken as key-points, and the IMU measurements may be used to interpolate in between the key-points.
  • P m be the locally registered point cloud from scan m.
  • Two sets of geometric features from P m may be extracted: one on sharp edges, namely edge points and denoted as ⁇ m , and the other on local planar surfaces, namely planar points and denoted as H m .
  • This is through computation of curvature in the local scans. Points whose neighbor points are already selected are avoided such as points on boundaries of occluded regions and points whose local surfaces are close to be parallel to laser beams. These points are likely to contain large noises or change positions over time as the sensor moves.
  • the associated eigenvalues and eigenvectors may be examined. Specifically, one large and two small eigenvalues indicate an edge line segment, and two large and one small eigenvalues indicate a local planar patch. If the matching is valid, an equation is formulated regarding the distance from a point to the corresponding point cluster,
  • the scan matching is formulated into an optimization problem 610 minimizing the overall distances described by Eq. 12.
  • the optimization also involves pose constraints 612 from prior motion.
  • T m _ t be the 4 x 4 transformation matrix regarding the pose of ⁇ Cm— 1 ⁇ in ⁇ W ⁇ , Tm-i is generated by processing the last scan.
  • Tm-i is generated by processing the last scan.
  • Eq. 14 refers to the case that the prior motion is from the visual-inertial odometry, assuming the camera is functional. Otherwise, the constraints are from the IMU prediction. may be used to denote the same terms by IMU mechanization. is a function of because integration of accelerations is dependent
  • the IMU pose constraints are, where ⁇ ' m is the corresponding relative covariance matrix.
  • Eqs. 14 and 15 are linearly combined into one set of constraints. The linear combination is determined by working mode of the visual-inertial odometry.
  • the optimization problem refines 6 m and t m , which is solved by the Newton gradient-descent method adapted to a robust fitting framework.
  • M m _ 1 denotes the set of voxels 702, 704 on the first level map 700 after processing the last scan.
  • Voxels 704 surrounding the sensor 706 form a subset M m-1 , denoted as S m _ 1 .
  • S m _ 1 Given a 6-DOF sensor pose, there is a corresponding S m-1 which
  • each voxel of the second level map 750 is a voxel of the second level map 750.
  • first level map 700 Before matching scans, points in and H m are projected onto the map using the best guess of motion, and fill them into Voxels 708 occupied by
  • Voxels 710 are those not occupied by points from or H m .
  • each voxel of the first level map 700 corresponds to a volume of space that is larger than a sub- voxel of the second level map 750.
  • each voxel of the first level map 700 comprises a plurality of sub- voxels in the second level map 750 and can be mapped onto the plurality of sub- voxels in the second level map 750.
  • two levels of voxels are used to store map information. Voxels corresponding to are used to maintain the first level map 700 and voxels corresponding in the second level map 750 are used to retrieve the map around the
  • the map is truncated only when the sensor approaches the map boundary. Thus, if the sensor navigates inside the map, no truncation is needed.
  • Another consideration is that two KD-trees are used for each individual voxel in S m _ 1 - one for edge points and the other for planar points. As noted above, such a data structure may accelerate point searching. In this manner, searching among multiple KD-trees is avoided as opposed to using two KD-trees for each individual voxel in The later requires more resources for KD-tree building and maintenance.
  • Table 1 compares CPU processing time using different voxel and KD-tree configurations. The time is averaged from multiple datasets collected from different types of environments covering confined and open, structured and vegetated areas. We see that using only one level of voxels, M m _ 1 , results in about twice of processing time for KD-tree building and querying. This is because the second level of voxels, help retrieve the map precisely. Without these voxel, more points are contained in Q m - and built into the KD- trees. Also, by using KD-trees for each voxel, processing time is reduced slightly in comparison to using KD-trees for all voxels in M m _ 1 .
  • FIG. 8A illustrates the case where two matcher programs 812, 815 run in parallel.
  • a manager program 810 arranges it to match with the latest map available.
  • matching is slow and may not complete before arrival of the next scan.
  • the two matchers 812 and 815 are called alternatively.
  • P m+ 1 , 816a P m- 1 , 816b and additional an odd integer) 816n are matched with Q m - 816a, Q m- 3 816a , and additional odd integer) 816n, respectively.
  • the use of this interleaving process may provide twice the amount of time for processing.
  • the final motion estimation is integration of outputs from the three modules depicted in FIG. 2.
  • the 5Hz scan matching output produces the most accurate map, while the 50Hz visual-inertial odometry output and the 200Hz IMU prediction are integrated for high- frequency motion estimates.
  • the robustness of the system is determined by its ability to handle sensor degradation.
  • the IMU is always assumed to be reliable functioning as the backbone in the system.
  • the camera is sensitive to dramatic lighting changes and may also fail in a dark/texture- less environment or when significant motion blur is present (thereby causing a loss of visual features tracking).
  • the laser cannot handle structure-less environments, for example a scene that is dominant by a single plane.
  • laser data degradation can be caused by sparsity of the data due to aggressive motion.
  • Both the visual-inertial odometry and the scan matching modules formulate and solve optimization problems according to EQ. 2.
  • a failure happens, it corresponds to a degraded optimization problem, i.e. constraints in some directions of the problem are ill- conditioned and noise dominates in determining the solution.
  • eigenvalues denoted as and eigenvectors, denoted as associated with the problem may be computed.
  • Six eigenvalues/eigenvectors are present because the state space of the sensor contains 6-DOF (6 degrees of freedom). Without losing generality, vi, v 2 , may be sorted in decreasing order. Each eigenvalue describes how well the solution is
  • well-conditioned directions may be separated from degraded directions in the state space.
  • Let h, h 0; 1, 6, be the number of well-conditioned directions.
  • Two matrices may be defined as:
  • the nonlinear iteration may start with an initial guess.
  • the IMU prediction provides the initial guess for the visual-inertial odometry, whose output is taken as the initial guess for the scan matching.
  • x be a solution
  • ⁇ x be an update of x in a nonlinear iteration, in which ⁇ x is calculated by solving the linearized system equations.
  • x may be updated only in well-conditioned directions, keeping the initial guess in degraded directions instead,
  • the system solves for motion in a coarse-to-fine order, starting with the IMU prediction, the additional two modules further solving/refining the motion as much as possible. If the problem is well-conditioned, the refinement may include all 6-DOF. Otherwise, if the problem is only partially well-conditioned, the refinement may include 0 to 5-DOF. If the problem is completely degraded, V becomes a zero matrix and the previous module's output is kept.
  • V v denote the matrices containing eigenvectors from the visual- inertial odometry module, represents well-conditioned directions in the subsystem
  • the IMU prediction 122 bypasses the visual-inertial odometry module 126 fully or partially 924 - denoted by the dotted line - depending on the number of well- conditioned directions in the visual-inertial odometry problem.
  • the scan matching module 132 may then locally register laser points for the scan matching.
  • the bypassing IMU prediction is subject to drift.
  • the laser feedback 138 compensates for the camera feedback 128 correcting velocity drift and biases of the IMU, only in directions where the camera feedback 128 is unavailable. Thus, the camera feedback has a higher priority, due to the higher frequency making it more suitable when the camera data are not degraded. When sufficient visual features are found, the laser feedback is not used.
  • the visual-inertial odometry module 126 output fully or partially bypasses the scan matching module to register laser points on the map 930 as noted by the dotted line. If well-conditioned directions exist in the scan matching problem, the laser feedback contains refined motion estimates in those directions. Otherwise, the laser feedback becomes empty 138.
  • FIG. 10 depicts such an example.
  • a vertical bar with six rows represents a 6- DOF pose where each row is a DOF (degree of freedom), corresponding to an eigenvector in EQ. 16.
  • the visual-inertial odometry and the scan matching each updates a 3- DOF of motion, leaving the motion unchanged in the other 3-DOF.
  • the IMU prediction 1022a- f may include initial IMU predicted values 1002.
  • the scan matching updates 1006 some 3-DOF (1032b, 1032d, 1032f) resulting in a further refined prediction 1032a-1032f.
  • the camera feedback 128 contains camera updates 1028a-1028f and the laser feedback 138 contains laser updates 1038a- 1038f, respectively.
  • cells having no shading (1028a, 1028b, 1028d, 1038a, 1038c, 1038e) do not contain any updating information from the respective modules.
  • the total update 1080a- 1080f to the IMU prediction modules is a combination of the updates 1028a-1028f from the camera feedback 128 and the updates 1038a-1038f from the laser feedback 138.
  • the camera updates (for example 1028f) may have priority over the laser updates (for example 1038f).
  • the visual-inertial odometry module and the scan matching module may execute at different frequencies and each may have its own degraded directions. IMU messages may be used to interpolate between the poses from the scan matching output. In this manner, an incremental motion that is time aligned with the visual-inertial odometry output may be created. Let be the 6-DOF motion estimated by the visual-inertial
  • V v and may be the matrices defined in Eq. 16 containing eigenvectors from the visual- inertial odometry module, in which V v represents well-conditioned directions, and V v — V v represents degraded directions.
  • f c only contains solved motion in a subspace of the state space.
  • the motion from the IMU prediction namely be projected to the null space of
  • [00123] may be used to denote the IMU predicted motion formulated as functions of through integration of Eqs. 3 and 4.
  • the orientation is om y relevant to but the translation is
  • f c spans the state space, and in Eq. 22 are zero matrices. Correspondingly, are calculated from/ c .
  • the IMU predicted motion is used in directions where the motion is unsolvable (e.g. white row 1080a of the combined feedback in FIG. 10). The result is that the previously calculated biases are kept in these directions.
  • a Velodyne LIDARTM HDL-32E laser scanner is attached to a UI-1220SE monochrome camera and an Xsens ® MTi-30 IMU.
  • the laser scanner has 360° horizontal FOV, 40° vertical FOV, and receives 0.7 million points/second at 5Hz spinning rate.
  • the camera is configured at the resolution of 752 x 480 pixels, 76° horizontal FOV, and 50Hz frame rate.
  • the IMU frequency is set at 200Hz.
  • a Velodyne LIDARTM VLP-16 laser scanner is attached to the same camera and IMU. This laser scanner has 360° horizontal FOV, 30° vertical FOV, and receives 0.3 million points/second at 5Hz spinning rate.
  • Each sensor suite is attached to a vehicle for data collection, which are driven on streets and in off -road terrains, respectively.
  • the software runs on a laptop computer with a 2.6GHz i7 quad-core processor (2 threads on each core and 8 threads overall) and an integrated GPU, in a Linux ® system running Robot Operating System (ROS).
  • ROS Robot Operating System
  • Two versions of the software were implemented with visual feature tracking running on GPU and CPU, respectively.
  • the processing time is shown in Table 2.
  • the time used by the visual-inertial odometry (126 in FIG. 2) does not vary much with respect to the environment or sensor configuration.
  • For the GPU version it consumes about 25% of a CPU thread executing at 50Hz.
  • For the CPU version it takes about 75% of a thread.
  • the sensor first suite results in slightly more processing time than the second sensor suite. This is because the scanner receives more points and the program needs more time to maintain the depthmap and associate depth to the visual features.
  • the scan matching consumes more processing time which also varies with respect to the environment and sensor configuration.
  • the scan matching takes about 75% of a thread executing at 5Hz if operated in structured environments. In vegetated environments, however, more points are registered on the map and the program typically consumes about 135% of a thread.
  • the scanner receives fewer points.
  • the scan matching module 132 uses about 50-95% of a thread depending on the environment.
  • the time used by the IMU prediction (132 in FIG. 2) is negligible compared to the other two modules.
  • Tests were conducted to evaluate accuracy of the proposed system. In these tests, the first sensor suite was used. The sensors were mounted on an off-road vehicle driving around a university campus. After 2.7km of driving within 16 minutes, a campus map was built. The average speed over the test was 2.8m/s.
  • FIG. 11 depicts estimated trajectories in an accuracy test.
  • a first trajectory plot 1102 of the trajectory of a mobile sensor generated by the visual-inertial odometry system uses the IMU module 122 and the visual-inertial odometry module 126 (see FIG. 2). The configuration used in the first trajectory plot 1102 is similar to that depicted in FIG. 9B.
  • a second trajectory plot 1104 is based on directly forwarding the IMU prediction from the IMU module 122 to the scan matching module, 132 (see FIG. 2) bypassing the visual-inertial odometry. This configuration is similar to that depicted in FIG. 9A.
  • a third trajectory plot 1108 of the complete pipeline is based on the combination of the IMU module 122, the visual inertial odometry module 126, and the scan matching module 132 (see FIG. 2) has the least amount of drift.
  • the position errors of the first two configurations, trajectory plot 1102 and 1104, are about four and two times larger, respectively.
  • the first trajectory plot 1102 and the second trajectory plot 1104 can be viewed as the expected system performance when encountering individual sensor degradation. If scan matching is degraded (see FIG. 9B), the system reduces to a mode indicated by the first trajectory plot 1102. If vision is degraded, (see FIG. 9A), the system reduces to a mode indicated by the second trajectory plot 1104. If none of the sensors is degraded, (see FIG 2) the system incorporates all of the optimization functions resulting in the trajectory plot 1108. In another example, the system may take the IMU prediction as the initial guess and but run at the laser frequency (5Hz). The system produces a fourth trajectory plot 1106.
  • the accuracy of the visual-inertial odometry and the IMU + scan matching configurations reduce significantly, by 0.54% and 0.38% of the distance traveled in comparison to the accuracy at lx speed.
  • the complete pipeline reduces accuracy very little, only by 0.04%. The results indicate that the camera and the laser compensate for each other keeping the overall accuracy. This is especially true when the motion is aggressive.
  • FIG. 12 there is illustrated an exemplary and non-limiting embodiment of bidirectional information flow.
  • three modules comprising an IMU prediction module, a visual-inertial odometry module and a scan-matching refinement module solve the problem step by step from coarse to fine.
  • Data processing flow is from left to right passing the three modules respectively, while feedback flow is from right to left to correct the biases of the IMU.
  • FIG. 13a With reference to Figs. 13a and 13b, there is illustrated an exemplary and non- limiting embodiment of a dynamically reconfigurable system.
  • the IMU prediction (partially) bypasses the visual-inertial odometry module to register laser points locally.
  • the visual-inertial odometry output (partially) bypasses the scan matching refinement module to register laser points on the map.
  • a vertical bar represents a 6-DOF pose and each row is a DOF.
  • the visual-inertial odometry updates in 3-DOF where the rows become designated "camera” then the scan matching updates in another 3-DOF where the rows turn designated "laser”.
  • the camera and the laser feedback is combined as the vertical bar on the left.
  • the camera feedback has a higher priority - "laser” rows from the laser feedback are only filled in if "camera” rows from the camera feedback are not present.
  • FIG. 15a and 15b there is illustrated an exemplary and non- limiting embodiment of two-layer voxel representation of a map.
  • voxels on the map M m _ 1 all voxels in Fig. 15a
  • voxels surrounding the sensor S m _ t dot filled voxels.
  • S m - 1 is a subset of M m _ 1 . If the sensor approaches the boundary of the map, voxels on the opposite side of the boundary (bottom row) are moved over to extend the map boundary. Points in moved voxels are cleared and the map is truncated.
  • each voxel (a dot filled voxel in Fig. 15a) is formed by a set of voxels m 1 that are a
  • the laser scan may be projected onto the map using the best guess of motion.
  • map points in cross-hatched voxels are extracted and stored in 3D KD-trees for scan matching.
  • Fig. 16 there is illustrated an exemplary and non-limiting embodiment of multi-thread processing of scan matching.
  • a manager program calls multiple matcher programs running on separate CPU threads and matches scans to the latest map available.
  • Fig. 16a shows a two-thread case. Scans are matched with
  • Fig. 16b shows a one-thread case, where are matched with Q m ,
  • the implementation is dynamically configurable using up to four threads.
  • a real time SLAM system may be used in combination with a real time navigation system.
  • the SLAM system may be used in combination with an obstacle detection system, such as a LIDAR- or RADAR-based obstacle detection system, a vision-based obstacle detection system, a thermal-based system, or the like. This may include detecting live obstacles, such as people, pets, or the like, such as by motion detection, thermal detection, electrical or magnetic field detection, or other mechanisms.
  • the point cloud that is established by scanning the features of an environment may be displayed, such as on a screen forming a part of the SLAM, to show a mapping of a space, which may include mapping of near field features, such as objects providing nearby reflections to the SLAM system, as well as far field features, such as items that can be scanned through spaces between or apertures in the near field features.
  • mapping of near field features such as objects providing nearby reflections to the SLAM system
  • far field features such as items that can be scanned through spaces between or apertures in the near field features.
  • items in an adjacent hallway may be scanned through a window or door as the mapper moves through the interior of a room, because at different points in the interior of the room different outside elements can be scanned through such spaces or apertures.
  • the resulting point cloud may then comprise comprehensive mapping data of the immediate near field environment and partial mapping of far field elements that are outside the environment.
  • the SLAM system may include mapping of a space through a "picket fence" effect by identification of far-field pieces through spaces or apertures (i.e., gaps in the fence) in the near field.
  • the far field data may be used to help the system orient the SLAM as the mapper moves from space to space, such as maintaining consistent estimation of location as the mapper moves from a comprehensively mapped space (where orientation and position are well known due to the density of the point cloud) to a sparsely mapped space (such as a new room).
  • the relative density or sparseness of the point cloud can be used by the SLAM system to guide the mapper via, for example, a user interface forming a part of the SLAM, such as directing the mapper to the parts of the far field that could not be seen through the apertures from another space.
  • the point cloud map from a SLAM system can be combined with mapping from other inputs such as cameras, sensors, and the like.
  • an airplane, drone, or other airborne mobile platform may already be equipped with other distance measuring and geo-location equipment that can be used as reference data for the SLAM system (such as linking the point cloud resulting from a scan to a GPS -referenced location) or that can take reference data from a scan, such as for displaying additional scan data as an overlay on the output from the other system.
  • conventional camera output can be shown with point cloud data as an overlay, or vice versa.
  • the SLAM system can provide a point cloud that includes data indicating the reflective intensity of the return signal from each feature.
  • This reflective intensity can be used to help determine the efficacy of the signal for the system, to determine how features relate to each other, to determine surface IR reflectivity, and the like.
  • the reflective intensity can be used as a basis for manipulating the display of the point cloud in a map.
  • the SLAM system can introduce (automatically, of under user control) some degree of color contrast to highlight the reflectivity of the signal for a given feature, material, structure, or the like.
  • the system can be married with other systems for augmenting color and reflectance information.
  • one or more of the points in the point cloud may be displayed with a color corresponding to a parameter of the acquired data, such as an intensity parameter, a density parameter, a time parameter and a geospatial location parameter.
  • Colorization of the point cloud may help users understand and analyze elements or features of the environment in which the SLAM system is operating and/or elements of features of the process of acquisition of the point cloud itself.
  • a density parameter indicating the number of points acquired in a geospatial area, may be used to determine a color that represents areas where many points of data are acquired and another color where data is sparse, perhaps suggesting the presence of artifacts, rather than "real" data.
  • Color may also indicate time, such as progressing through a series of colors as the scan is undertaken, resulting in clear indication of the path by which the SLAM scan was performed. Colorization may also be undertaken for display purposes, such as to provide differentiation among different features (such as items of furniture in a space, as compared to walls), to provide aesthetic effects, to highlight areas of interest (such as highlighting a relevant piece of equipment for attention of a viewer of a scan), any many others.
  • the SLAM system can identify "shadows" (areas where the point cloud has relatively few data points from the scan) and can (such as through a user interface) highlight areas that need additional scanning. For example, such areas may blink or be rendered in a particular color in a visual interface of a SLAM system that displays the point cloud until the shadowed area is sufficiently "painted," or covered, by laser scanning.
  • Such an interface may include any indicator (visual, text-based, voice-based, or the like) to the user that highlights areas in the field that have not yet been scanned, and any such indicator may be used to get the attention of the user either directly or through an external device (such as a mobile phone of the user).
  • the system may make reference to external data of data stored on the SLAM, such as previously constructed point clouds, maps, and the like, for comparison with current scan to identify unscanned regions.
  • the methods and systems disclosed herein include a SLAM system that provides real-time positioning output at the point of work, without requiring processing or calculation by external systems in order to determine accurate position and orientation information or to generate a map that consists of point cloud data showing features of an environment based on the reflected signals from a laser scan.
  • the methods and systems disclosed herein may also include a SLAM system that provides real time positioning information without requiring post-processing of the data collected from a laser scan.
  • a SLAM system may be integrated with various external systems, such as vehicle navigation systems (such as for unmanned aerial vehicles, drones, mobile robots, unmanned underwater vehicles, self-driving vehicles, semi-automatic vehicles, and many others).
  • vehicle navigation systems such as for unmanned aerial vehicles, drones, mobile robots, unmanned underwater vehicles, self-driving vehicles, semi-automatic vehicles, and many others.
  • the SLAM system may be used to allow a vehicle to navigate within its environments, without reliance on external systems like GPS.
  • a SLAM system may determine a level of confidence as to its current estimation of position, orientation, or the like.
  • a level of confidence may be based on the density of points that are available in a scan, the orthogonality of points available in a scan, environmental geometries or other factors, or a combination thereof.
  • the level of confidence may be ascribed to position and orientation estimates at each point along the route of a scan, so that segments of the scan can be referenced as low-confidence segments, high-confidence segments, or the like. Low-confidence segments can be highlighted for additional scanning, for use of other techniques (such as making adjustments based on external data), or the like.
  • any discrepancy between the calculated end location and the starting location may be resolved by preferentially adjusting location estimates for certain segments of the scan to restore consistency of the start- and end- locations.
  • Location and position information in low-confidence segments may be preferentially adjusted as compared to high-confidence segments.
  • the SLAM system may use confidence-based error correction for closed loop scans.
  • confidence measures with respect to areas or segments of a point cloud may be used to guide a user to undertake additional scanning, such as to provide an improved SLAM scan.
  • a confidence measure can be based on a combination of density of points, orthogonality of points and the like, which can be used to guide the user to enable a better scan.
  • scan attributes such as density of points and orthogonality of points
  • the system may sense geometries of the scanning environment that are likely to result in low confidence measures. For example, long hallways with smooth walls may not present any irregularities to differentiate one scan segment from the next. In such instances, the system may assign a lower confidence measure to scan data acquired in such environments.
  • the system can use various inputs such as LIDAR, camera, and perhaps other sensors to determine diminishing confidence and guide the user through a scan with instructions (such as "slow down,” "turn left” or the like).
  • the system may display areas of lower than desired confidence to a user, such as via a user interface, while providing assistance in allowing the user to further scan the area, volume or region of low confidence.
  • a SLAM output may be fused with other content, such as outputs from cameras, outputs from other mapping technologies, and the like.
  • a SLAM scan may be conducted along with capture of an audio track, such as via a companion application (optionally a mobile application) that captures time-coded audio notes that correspond to a scan.
  • the SLAM system provides time-coding of data collection during scanning, so that the mapping system can pinpoint when and where the scan took place, including when and where the mapper took audio and/or notes.
  • the time coding can be used to locate the notes in the area of the map where they are relevant, such as by inserting data into a map or scan that can be accessed by a user, such as by clicking on an indicator on the map that audio is available.
  • other media formats may be captured and synchronized with a scan, such as photography, HD video, or the like. These can be accessed separately based on time information, or can be inserted at appropriate places in a map itself based on the time synchronization of the scan output with time information for the other media.
  • a user may use time data to go back in time and see what has changed over time, such as based on multiple scans with different time-encoded data.
  • Scans may be further enhanced with other information, such as date- or time-stamped service record data.
  • a scan may be part of a multi-dimensional database of a scene or space, where point cloud data is associated with other data or media related to that scene, including time-based data or media.
  • calculations are maintained through a sequence of steps or segments in a manner that allows a scan to be backed up, such as to return to a given point in the scan and re-initiate at that point, rather than having to re-initiate a new scan starting at the origin. This allows use of partial scan information as a starting point for continuing a scan, such as when a problem occurs at a later point in a scan that was initially producing good output.
  • a user can "unzip” or “rewind” a scan back to a point, and then recommence scanning from that point.
  • the system can maintain accurate position and location information based on the point cloud features and can maintain time information to allow sequencing with other time-based data.
  • Time-based data can also allow editing of a scan or other media to synchronize them, such as where a scan was completed over time intervals and needs to be synchronized with other media that was captured over different time intervals.
  • Data in a point cloud may be tagged with timestamps, so that data with timestamps occurring after a point in time to which a rewind is undertaken can be erased, such that the scan can re-commence from a designated point.
  • a rewind may be undertaken to a point in time and/or to a physical location, such as rewinding to a geospatial coordinate.
  • the output from a SLAM-based map can be fused with other content, such as HD video, including by colorizing the point cloud and using it as an overlay. This may include time-synchronization between the SLAM system and other media capture system.
  • Content may be fused with video, still images of a space, a CAD model of a space, audio content captured during a scan, metadata associated with a location, or other data or media.
  • a SLAM system may be integrated with other technologies and platforms, such as tools that may be used to manipulate point clouds (e.g., CAD). This may include combining scans with features that are modeled in CAD modeling tools, rapid prototyping systems, 3D printing systems, and other systems that can use point cloud or solid model data. Scans can be provided as inputs to post-processing tools, such as colorization tools. Scans can be provided to mapping tools, such as for adding points of interest, metadata, media content, annotations, navigation information, semantic analysis to distinguish particular shapes and/or identify objects, and the like.
  • Outputs can be combined with outputs from other scanning and image-capture systems, such as ground penetrating radar, X-ray imaging, magnetic resonance imaging, computed tomography imaging, thermal imaging, photography, video, SONAR, RADAR, LIDAR and the like.
  • This may include integrating outputs of scans with displays for navigation and mapping systems, such as in-vehicle navigation systems, handheld mapping systems, mobile phone navigation systems, and others.
  • Data from scans can be used to provide position and orientation data to other systems, including X, Y and Z position information, as well as pitch, roll and yaw information.
  • the data obtained from a real time SLAM system can be used for many different purposes, including for 3D motion capture systems, for acoustics engineering applications, for biomass measurements, for aircraft construction, for archeology, for architecture, engineering and construction, for augmented reality (AR), for autonomous cars, for autonomous mobile robot applications, for cleaning and treatment, for CAD/CAM applications, for construction site management (e.g., for validation of progress), for entertainment, for exploration (space, mining, underwater and the like), for forestry (including for logging and other forestry products like maple sugar management), for franchise management and compliance (e.g., for stores and restaurants), for imaging applications for validation and compliance, for indoor location, for interior design, for inventory checking, for landscape architecture, for mapping industrial spaces for maintenance, for mapping trucking routes, for military/intelligence applications, for mobile mapping, for monitoring oil pipelines and drilling, for property evaluation and other real estate applications, for retail indoor location (such as marrying real time maps to inventory maps, and the like), for security applications, for stockpile monitoring (ore, logs, goods
  • the unit comprises hardware synchronization of the IMU, camera (vision) and the LiDAR sensor.
  • the unit may be operated in darkness or structureless environments for a duration of time.
  • the processing pipeline may be comprised of modules. In darkness, the vision module may be bypassed. In structureless environments, the LiDAR module may be bypassed or partially bypassed.
  • the IMU, Lidar and camera data are all time stamped and capable of being temporally matched and synchronized. As a result, the system can act in an automated fashion to synchronize image data and point cloud data. In some instances, color data from synchronized camera images may be used to color clod data pixels for display to the user.
  • the unit may comprise four CPU threads for scan matching and may run at, for example, 5Hz with Velodyne data.
  • the motion of the unit when operating may be relatively fast.
  • the unit may operate at angular speeds of approximately 360 degree/second and linear speeds of approximately 30m/s.
  • the unit may localize to a prior generated map.
  • the unit's software may refer to a previously built map and produce sensor poses and a new map within the framework (e.g., geospatial or other coordinates) of the old map.
  • the unit can further extend a map using localization.
  • By developing a new map in the old map frame, the new map can go further on and out of the old map.
  • branching and chaining in which an initial "backbone" scan is generated first and potentially post-processed to reduce drift and/or other errors before resuming from the map to add local details, such as side rooms in building or increased point density in a region of interest.
  • the backbone model may be generated with extra care to limit the global drift and the follow-on scans may be generated with the focus on capturing local detail. It is also possible for multiple devices to perform the detailed scanning off of the same base map for faster capture of a large region.
  • Resuming may also provide location registered temporal data. For example, multiple scans may be taken of a construction site over time to see the progress visually. In other embodiments multiple scans of a factory may help with tracking for asset management.
  • Resuming may alternately be used to purely provide localization data within the prior map. This may be useful for guiding a robotic vehicle or localizing new sensor data, such as images, thermal maps, acoustics, etc within an existing map.
  • the unit employs relatively high CPU usage in a mapping mode and relatively low CPU usage in a localization mode, suitable for long-time localization/navigation.
  • the unit supports long-time operations by executing an internal reset every once in a while. This is advantageous as some of the values generated during internal processing increase over time. Over a long period of operation (e.g., a few days), the values may reach a limit, such as a logical or physical limit of storage for the value in a computer, causing the processing, absent a reset, to potentially fail.
  • the system may automatically flush RAM memory to improve performance.
  • the system may selectively down sample older scanned data as might be necessary when performing a real time comparison of newly acquired data with older and/or archived data.
  • the unit may support a flying application and aerial-ground map merging.
  • the unit may compute a pose output at the IMU frequency, e.g., 100Hz.
  • the software may produce maps as well as sensor poses.
  • the sensor poses tell the sensor position and pointing with respect to the map being developed. High frequency and accurate pose output helps in mobile autonomy because vehicle motion control requires such data.
  • the unit further employs covariance and estimation confidence and may lock a pose when the sensor is static.
  • a SLAM LIDAR is rotated to create a substantially hemispherical scan. This is performed by a mechanism with a DC motor driving a spur gear reduction to LIDAR mount via a spur gear assembly 1704.
  • the spur gear reduction assembly 1704 enables the LIDAR to be offset from the motor 1708.
  • An encoder 1706 is also in line with the rotation of the LIDAR to record the orientation of the mechanism during scanning.
  • a thin section contact bearing supports the LIDAR rotation shaft.
  • SLAM enclosure 1802 there is illustrated an exemplary and non- limiting embodiment of a SLAM enclosure 1802.
  • the SLAM enclosure 1802 is depicted in a variety of views and perspectives. Dimensions are representative of an embodiment and non-limiting as the size may be similar or different, while maintaining the general character and orientation of the major components, such as the LIDAR, odometry camera, colorization camera, user interface screen, and the like.
  • the unit may employ a neck brace, shoulder brace, carrier, or other wearable element or device (not shown), such as to help an individual hold the unit while walking around.
  • the unit or a supporting element or device may include one or more stabilizing elements to reduce shaking or vibration during the scan.
  • the unit may employ a remote battery that is carried in a shoulder bag or the like to reduce the weight of the handheld unit, whereby the scanning device has an external power source.
  • the cameras and LIDAR are arranged to maximize a field of view.
  • the camera-laser arrangement poses a tradeoff. On one side, the camera blocks the laser FOV and on the other side, the laser blocks the camera. In such an arrangement, both are blocked slightly but the blocking does not significantly sacrifice the mapping quality.
  • the camera points in the same direction as the laser because the vision processing is assisted by laser data. Laser range measurements provide depth information to the image features in the processing.
  • a confidence metric representing a confidence of spatial data.
  • Such a confidence metric measurement may include, but is not limited to, number of points, distribution of points, orthogonality of points, environmental geometry, and the like.
  • One or more confidence metrics may be computed for laser data processing (e.g., scan matching) and for image processing.
  • Figs. 19(a)- 19(c) there are illustrated exemplary and non-limiting example images showing point clouds differentiated by laser match estimation confidence. While in practice, such images may be color coded, as illustrated, both the trajectory and the points are rendered as solid or dotted in the cloud based on a last confidence value at the time of recording. In the examples, dark gray is bad and light gray is good. The values are thresholded such that everything with a value >10 is solid. Through experimentation it has been found that with a Velodyne ⁇ 1 is unreliable, ⁇ 10 is less reliable, >10 is very good.
  • Using these metrics enables automated testing to resolve model issues and offline model correction such as when utilizing a loop-closure tool as discussed elsewhere herein. Use of these metrics further enables alerting the user when matches are bad and possibly auto- pausing, throwing out low confidence data, and alerting the user when scanning.
  • Fig. 19(a) illustrates a scan of a building floor performed at a relatively slow pace.
  • Fig. 19(b) illustrates a scan of the same building floor performed at a relatively quicker pace. Note the prevalence of light fray when compared to the scan acquired from a slower scan pace arising, in part, from the speed at which the scan is conducted.
  • Fig. 19(c) illustrates a display zoomed in on a potential trouble spot of relatively low confidence.
  • Fig. 20 there is illustrated an exemplary and non-limiting embodiment of scan-to-scan match confidence metric processing and an average number of visual features that track between a full laser scan and a map being built from the prior full laser scans may be computed and presented visually. This metric may present useful, but different confidence measures.
  • a laser scan confidence metric view is presented in the left frame while an average number of visual features metric is presented in the right frame for the same data. Again, dark gray line indicates lower confidence and/or fewer average number of visual features.
  • loop closure there may be employed loop closure.
  • the unit may be operated as one walks around a room, cubicle, in and out of offices, and then back to a starting point.
  • the mesh of data from the start and end point should mesh exactly.
  • the algorithms described herein greatly minimize such drift. Typical reduction is on the order of lOx versus conventional methods (0.2% v 2%). This ratio reflects the error in distance between the start point and end point divided by the total distance traversed during the loop.
  • the software recognizes that it is back to a starting point and it can relock to the origin. Once done, one may take the variation and spread it over all of the collected data.
  • one may lock in certain point cloud data where a confidence metric indicates that the data confidence was poor and one may apply the adjustments to the areas with low confidence.
  • the system may employ both explicit and implicit loop closure.
  • a user may indicate, such as via a user interface forming a part of the SLAM, that a loop is to be closed.
  • This explicit loop closure may result in the SLAM executing software that operates to match recently scanned data to data acquired at the beginning of the loop in order to snap the beginning and end acquired data together and close the loop.
  • the system may perform implicit loop closure. In such instances, the system may operate in an automated fashion to recognize that the system is actively rescanning a location that that comprises a point or region of origin for the scan loop.
  • each pixel in the camera can be mapped to a unique LIDAR pixel. For example, one may take color data from a pixel in the colorization camera corresponding to LIDAR data in the point cloud, and add the color data to the LIDAR data.
  • the unit may employ a sequential, multi-layer processing pipeline, solving for motion from coarse to fine.
  • the prior coarser result is used as an initial guess to the optimization problem.
  • the steps in the pipeline are:
  • this estimate is further refined by a laser odometry optimization at a lower rate determined by the "scan frame" rate.
  • Scan data comes in continuously, and software segments that data into frames, similar to image frames, at a regular rate, currently that rate is the time it takes for one rotation of the LIDAR rotary mechanism to make each scan frame a full hemisphere of data. That data is stitched together using visual-inertial estimates of position change as the points within the same scan frame are gathered.
  • the visual odometry estimate is taken as an initial guess and the optimization attempts to reduce residual error in tracked features in the current scan frame matched to the prior scan frame.
  • the current scan frame is matched to the entire map so far.
  • the laser odometry estimate is taken as the initial guess and the optimization minimizes residual squared errors between features in the current scan frame and features in the map so far.
  • the resulting system enables high-frequency, low-latency ego-motion estimation, along with dense, accurate 3D map registration. Further, the system is capable of handling sensor degradation by automatic reconfiguration bypassing failure modules since each step can correct errors in the prior step. Therefore, it can operate in the presence of highly dynamic motion as well as in dark, texture-less, and structure-less environments. During experiments, the system demonstrates 0.22% of relative position drift over 9.3km of navigation and robustness with respect to running, jumping and even highway speed driving (up to 33m/s).
  • Visual feature optimization / and /o depth The software may attempt to determine a depth of tracked visual features, first by attempting to associate them with the laser data and secondly by attempting to triangulate depth between camera frames. The feature optimization software may then utilize all features with two different error calculations, one for features with depth and one for features without depth.
  • Laser feature determination The software may extract laser scan features as the scan line data comes in rather than in the entire scan frame. This is much easier and is done by looking at the smoothness at each point, which is defined by the relative distance between that point and the K nearest points on either side of that point then labeling the smoothest points as planar features and the sharpest as edge features. It also allows for the deletion of some points that may be bad features.
  • Map matching and voxelization A part of how the laser matching works in real-time is how the map and feature data is stored. Tracking the processor load of this stored data is critical to long term scanning and selectively voxelizing, or down-sampling into three-deminsional basic units in order to minimize the data stored while keeping what is needed for accurate matching. Adjusting the voxel sizes, or basic units, of this down-sampling on the fly based on processor load may improve the ability to maintaining real-time performance in large maps.
  • the software may be setup in such a way that it can utilize parallel processing to maintain real-time performance if data comes in faster than the processor can handle it. This is more relevant with faster point/second LIDARS like the velodyne.
  • Each optimization step in this process may provide information on the confidence in its own results. In particular, in each step, the following can be evaluated to provide a measure of confidence in results: the remaining residual squared error after the optimization, the number of features tracked between frames, and the like.
  • the user may be presented a down scaled, (e.g., sub sampled) version of the multi- spectral model being prepared with data being acquired by the device.
  • each measured 3cm x 3cm x 3cm cube of model data may be represented in the scaled down version presented on the user interface as a single pixel.
  • the pixel selected for display may be the pixel that is closest to the center of the cube.
  • a representative down-scaled display being generated during operation of the SLAM is shown below.
  • the decision to display a single pixel in a volume represents a binary result indicative of either the presence of one or more points in a point cloud occupying a spatial cube of defined dimensions or the absence of any such points.
  • the selected pixel may be attributed, such as with a value indicating the number of pixels inside the defined cube represented by the selected pixel. This attribute may be utilized when displaying the sub sampled point cloud such as by displaying each selected pixel utilizing color and/or intensity to reflect the value of the attribute.
  • a visual frame comprises a single 2D color image from the colorization camera.
  • a LIDAR segment comprises s full 360 degree revolution of the LIDAR scanner.
  • the visual frame and LIDAR segment are synchronized so that they can be combined and aligned with the existing model data based on the unit positional data captured from the IMU and related sensors, such as the odometry (e.g., a high speed black/white) camera.
  • the odometry e.g., a high speed black/white
  • a user of the unit may pause and resume a scan such as by, for example, hitting a pause button and/or requesting a rewind to a point that is a predetermined or requested number of seconds in the past.
  • rewinding during a scan may proceed as follows.
  • the user of the system indicates a desire to rewind. This may be achieved through the manipulation of user interface forming a part of the SLAM.
  • the system deletes or otherwise removes a portion of scanned data points corresponding to a duration of time. As all scanned data points are time stamped, the system can effectively remove data points after a predetermined time, thus, "rewinding" back to a previous point in a scan.
  • the system may provide the user with a display of an image recorded at the predetermined point in time while displaying the scanned point cloud rewound to the predetermined point in time.
  • the image acts as a guide to help the user of the system reorient the SLAM into a position closely matching the orientation and pose of the SLAM at the previous predetermined point in time.
  • the user may indicate a desire to resume scanning such as by engaging a "Go" button on a user interface of the SLAM.
  • the SLAM may proceed execute a processing pipeline utilizing newly scanned data to form an initial estimation of the SLAMs position and orientation.
  • the SLAM may not add new data to the scan but, rather, may use the newly scanned data to determine and display an instantaneous confidence level of the user's position as well as a visual representation of the extent to which newly acquired data corresponds to the previous scan data.
  • scanning may continue.
  • this ability to rewind is enabled, in part, by the data being stored.
  • One may estimate how many points are brought in per second and then estimate how much to "rewind".
  • the unit may inform the user where he was x seconds a go and allow the user to move to that location and take a few scans to confirm that the user is at the appropriate place. For example, the user may be told an approximate place to go to (or the user indicate where they want to restart). If the user is close enough, the unit may figure it out where the user is and tell the user if they are close enough.
  • the unit may operate in transitions between spaces. For example, If a user walks very quickly through a narrow doorway there may not be enough data and time to determine the user's place in the new space. Specifically, in this example, the boundaries of a door frame may, prior to proceeding through it, block the LIDAR from imaging a portion of the environment beyond the door sufficient to establish a user's location. One option is to detect this lowering of confidence metric and signal to the operator to modify his behavior upon approaching a narrow passage to slow down, such as by a flashing a visual indicator or a changing the color of the screen, and the like.
  • the SLAM unit 2100 may include a timing server to generate multiple signals derived from the IMU's 2106 pulse -per-second (PPS) signal. The generated signals may be used to synchronize the data collected from the different sensors in the unit.
  • a microcontroller 2102 may be used to generate the signals and communicate with the CPU 2104.
  • the quadrature decoder 2108 may either be built into the microcontroller or on an external IC.
  • the IMU 2206 supplies a rising edge PPS signal that is used to generate the timing pulses for other parts of the system.
  • the camera may receive three signals generated from the IMU PPS signal including one rising edge signal as described above and two falling edge signals, GPIOl (lasting one frame) and GPI02 (lasting two frames as illustrated with reference to Fig. 22.
  • each camera receives a trigger signal synchronized with the IMU PPS having a high frame rate of approximately 30 Hz or 40 Hz and a high resolution of approximately 0.5 Hz - 5 Hz.
  • Each IMS PPS pulse may zero a counter internal to the microcontroller 2202.
  • the LIDAR' s synchronous output may trigger the following events:
  • the encoder and the counter values may be saved together and sent to the CPU. This may happen every 40 Hz, dictated by the LIDAR synchronous output as illustrated with reference to Fig. 23.
  • An alternate time synchronization technique may include IMU based pulse-per- second synchronization that facilitates synchronizing the sensors and the computer processor.
  • IMU based pulse-per- second synchronization that facilitates synchronizing the sensors and the computer processor.
  • An exemplary and non-limiting embodiment of this type of synchronization is depicted with reference to Fig. 24.
  • the IMU 2400 may be configured to send a Pulse Per Second (PPS) signal 2406 to a LIDAR 2402. Every time a PPS is sent, the computer 2404 is notified by recognizing a flag in the IMU data stream. Then, the computer 2404 follows up and sends a time string to the LIDAR 2402. The LIDAR 2402 synchronizes to the PPS 2406 and encodes time stamps in the LIDAR data stream based on the received time strings.
  • PPS Pulse Per Second
  • the computer 2404 Upon receiving the first PPS 2406, the computer 2404 records its system time. Starting from the second PPS, the computer 2404 increases the recorded time by one second, sends the resulting time string to the LIDAR 2402, and then corrects its own system time to track the PPS 2506.
  • the IMU 2400 functions as the time server, while the initial time is obtained from the computer system time.
  • the IMU 2400 data stream is associated with time stamps based on its own clock, and initialized with the computer system time when the first PPS 2406 is sent. Therefore, the IMU2400, LIDAR 2402, and computer 2404 are all time synchronized.
  • the LIDAR 2402 may be a Velodyne LIDAR.
  • the unit includes a COM express board and a single button interface for scanning.
  • the process IMU, vision and laser data sensors may be coupled.
  • the unit may work in darkness or structureless environments for long periods of time.
  • four CPU threads may be employed for scan matching, each running at 5Hz with Velodyne data.
  • motion of the unit may be fast and the unit may localize to a prior map and can extend a map using localization.
  • the unit exhibits relatively high CPU usage in mapping mode and relatively low CPU usage in localization mode thus rendering it suitable for long-time.
  • a method comprising: acquiring a LIDAR point cloud comprising a plurality of points each of which are attributed with at least a geospatial coordinate and a segment, assigning a confidence level to each segment indicative of a computed accuracy of the plurality of points attributed with the same segment and adjusting the geospatial coordinate of each of at least a portion of the plurality of points attributed with the same segment based, at least in part, on a confidence level.
  • Clause 4 The method of clause 1, wherein a segment for adjusting the geospatial coordinate has a lower confidence level than at least one other segment.
  • a method comprising: commencing to acquire a LIDAR point cloud with a SLAM the point cloud having a starting location and comprising a plurality of points each of which are attributed with at least a geospatial coordinate and a segment, traversing a loop while acquiring the LIDAR point cloud and determining a scan end point when the SLAM is in proximity to the starting location.
  • a method comprising: acquiring a LIDAR point cloud comprising a plurality of points each of which are attributed with at least a geospatial coordinate and a timestamp, acquiring color image data comprising a plurality of images each of which are attributed with at least one of the geospatial coordinates and the timestamp and colorizing at least a portion of the plurality of points with color information derived from an image having a timestamp that is close in time to the timestamp of each point being colorized and having a geospatial coordinate that is close in proximity to the geospatial coordinate of the colorized plurality of points.
  • a method comprising: deriving a motion estimate for a SLAM system using an IMU forming a part of the SLAM system, refining the motion estimate via a visual- inertial odometry optimization process to produce a refined estimate and refining the refined estimate via a laser odometry optimization process by minimizing at least one residual squared error between at least one feature in a current scan and at least one previously scanned feature.
  • Clause 16 The method of clause 11, wherein the laser odometry optimization process is performed at a scan frame rate at which a LIDAR rotary mechanism forming a part of the SLAM scans a full hemisphere of data.
  • a method comprising: acquiring a plurality of depth tracked visual features in a plurality of camera frames using a camera forming a part of a SLAM system, associating the plurality of visual features with a LIDAR derived point cloud acquired from a LIDAR forming a part of the SLAM and triangulating a depth of at least one visual feature between at least two camera frames.
  • Clause 18 The method of clause 17, where in the associating and triangulating steps are performed on a processor employing parallel computing.
  • a SLAM device comprising: a microcontroller, an inertial measurement unit (IMU) adapted to produce a plurality of timing signals and a timing server adapted to generate a plurality of synchronization signals derived from the plurality of timing signals, wherein the synchronization signals operate to synchronize at least two sensors forming a part of the SLAM device.
  • IMU inertial measurement unit
  • Clause 20 The SLAM device of clause 20, wherein the at least two sensors are selected from the group consisting of LIDAR, a camera and an IMU.
  • a method comprising: acquiring a LIDAR point cloud comprising a plurality of points each of which are attributed with at least a geospatial coordinate and a timestamp, acquiring color image data comprising a plurality of images each of which are attributed with at least the geospatial coordinate and the timestamp, colorizing at least a portion of the plurality of points with color information derived from an image having at least one of a timestamp that is close in time to the timestamp of each point being colorized and a geospatial coordinate that is close in distance to the geospatial coordinate of each point being colorized and displaying the colorized portion of the plurality of points.
  • Clause 22 The method of clause 21, further comprising displaying output from a camera as an overlay on the displayed plurality of points.
  • a method comprising acquiring a LIDAR point cloud comprising a plurality of points each of which are attributed with at least a geospatial coordinate and a timestamp and colorizing at least a portion of the plurality of points with color information, wherein each of the plurality of points is colorized with a color corresponding to a parameter of the acquired LIDAR point cloud data selected from the group consisting of an intensity parameter, a density parameter, a time parameter and a geospatial location parameter.
  • a method comprising: acquiring a LIDAR point cloud with a SLAM comprising a plurality of near field points derived from a corresponding near environment and a plurality of far field points derived from a corresponding far field environment wherein the far field points are scanned through one or more spaces between one or more elements located in the near environment and utilizing the plurality of far field points to orient the SLAM as it moves form the near environment to the far environment.
  • the methods and systems described herein may be deployed in part or in whole through a machine that executes computer software, program codes, and/or instructions on a processor.
  • the present disclosure may be implemented as a method on the machine, as a system or apparatus as part of or in relation to the machine, or as a computer program product embodied in a computer readable medium executing on one or more of the machines.
  • the processor may be part of a server, cloud server, client, network infrastructure, mobile computing platform, stationary computing platform, or other computing platform.
  • a processor may be any kind of computational or processing device capable of executing program instructions, codes, binary instructions and the like.
  • the processor may be or may include a signal processor, digital processor, embedded processor, microprocessor or any variant such as a co-processor (math co-processor, graphic co-processor, communication co-processor and the like) and the like that may directly or indirectly facilitate execution of program code or program instructions stored thereon.
  • the processor may enable execution of multiple programs, threads, and codes. The threads may be executed simultaneously to enhance the performance of the processor and to facilitate simultaneous operations of the application.
  • methods, program codes, program instructions and the like described herein may be implemented in one or more thread.
  • the thread may spawn other threads that may have assigned priorities associated with them; the processor may execute these threads based on priority or any other order based on instructions provided in the program code.
  • the processor may include non- transitory memory that stores methods, codes, instructions and programs as described herein and elsewhere.
  • the processor may access a non-transitory storage medium through an interface that may store methods, codes, and instructions as described herein and elsewhere.
  • the storage medium associated with the processor for storing methods, programs, codes, program instructions or other type of instructions capable of being executed by the computing or processing device may include but may not be limited to one or more of a CD-ROM, DVD, memory, hard disk, flash drive, RAM, ROM, cache and the like.
  • a processor may include one or more cores that may enhance speed and performance of a multiprocessor.
  • the process may be a dual core processor, quad core processors, other chip-level multiprocessor and the like that combine two or more independent cores (called a die).
  • the methods and systems described herein may be deployed in part or in whole through a machine that executes computer software on a server, client, firewall, gateway, hub, router, or other such computer and/or networking hardware.
  • the software program may be associated with a server that may include a file server, print server, domain server, internet server, intranet server, cloud server, and other variants such as secondary server, host server, distributed server and the like.
  • the server may include one or more of memories, processors, computer readable media, storage media, ports (physical and virtual), communication devices, and interfaces capable of accessing other servers, clients, machines, and devices through a wired or a wireless medium, and the like.
  • the methods, programs, or codes as described herein and elsewhere may be executed by the server.
  • other devices required for execution of methods as described in this application may be considered as a part of the infrastructure associated with the server.
  • the server may provide an interface to other devices including, without limitation, clients, other servers, printers, database servers, print servers, file servers, communication servers, distributed servers, social networks, and the like. Additionally, this coupling and/or connection may facilitate remote execution of program across the network. The networking of some or all of these devices may facilitate parallel processing of a program or method at one or more location without deviating from the scope of the disclosure.
  • any of the devices attached to the server through an interface may include at least one storage medium capable of storing methods, programs, code and/or instructions.
  • a central repository may provide program instructions to be executed on different devices.
  • the remote repository may act as a storage medium for program code, instructions, and programs.
  • the software program may be associated with a client that may include a file client, print client, domain client, internet client, intranet client and other variants such as secondary client, host client, distributed client and the like.
  • the client may include one or more of memories, processors, computer readable media, storage media, ports (physical and virtual), communication devices, and interfaces capable of accessing other clients, servers, machines, and devices through a wired or a wireless medium, and the like.
  • the methods, programs, or codes as described herein and elsewhere may be executed by the client.
  • other devices required for execution of methods as described in this application may be considered as a part of the infrastructure associated with the client.
  • the client may provide an interface to other devices including, without limitation, servers, other clients, printers, database servers, print servers, file servers, communication servers, distributed servers and the like. Additionally, this coupling and/or connection may facilitate remote execution of program across the network. The networking of some or all of these devices may facilitate parallel processing of a program or method at one or more location without deviating from the scope of the disclosure.
  • any of the devices attached to the client through an interface may include at least one storage medium capable of storing methods, programs, applications, code and/or instructions.
  • a central repository may provide program instructions to be executed on different devices.
  • the remote repository may act as a storage medium for program code, instructions, and programs.
  • the methods and systems described herein may be deployed in part or in whole through network infrastructures.
  • the network infrastructure may include elements such as computing devices, servers, routers, hubs, firewalls, clients, personal computers, communication devices, routing devices and other active and passive devices, modules and/or components as known in the art.
  • the computing and/or non-computing device(s) associated with the network infrastructure may include, apart from other components, a storage medium such as flash memory, buffer, stack, RAM, ROM and the like.
  • the processes, methods, program codes, instructions described herein and elsewhere may be executed by one or more of the network infrastructural elements.
  • SaaS software as a service
  • PaaS platform as a service
  • IaaS infrastructure as a service
  • the methods, program codes, and instructions described herein and elsewhere may be implemented on a cellular network haa sender-controlled contact media content item multiple cells.
  • the cellular network may either be frequency division multiple access (FDMA) network or code division multiple access (CDMA) network.
  • FDMA frequency division multiple access
  • CDMA code division multiple access
  • the cellular network may include mobile devices, cell sites, base stations, repeaters, antennas, towers, and the like.
  • the cell network may be a GSM, GPRS, 3G, EVDO, mesh, or other networks types.
  • the methods, program codes, and instructions described herein and elsewhere may be implemented on or through mobile devices.
  • the mobile devices may include navigation devices, cell phones, mobile phones, mobile personal digital assistants, laptops, palmtops, netbooks, pagers, electronic books readers, music players and the like. These devices may include, apart from other components, a storage medium such as a flash memory, buffer, RAM, ROM and one or more computing devices.
  • the computing devices associated with mobile devices may be enabled to execute program codes, methods, and instructions stored thereon. Alternatively, the mobile devices may be configured to execute instructions in collaboration with other devices.
  • the mobile devices may communicate with base stations interfaced with servers and configured to execute program codes.
  • the mobile devices may communicate on a peer-to-peer network, mesh network, or other communications network.
  • the program code may be stored on the storage medium associated with the server and executed by a computing device embedded within the server.
  • the base station may include a computing device and a storage medium.
  • the storage device may store program codes and instructions executed by the computing devices associated
  • the computer software, program codes, and/or instructions may be stored and/or accessed on machine readable media that may include: computer components, devices, and recording media that retain digital data used for computing for some interval of time; semiconductor storage known as random access memory (RAM); mass storage typically for more permanent storage, such as optical discs, forms of magnetic storage like hard disks, tapes, drums, cards and other types; processor registers, cache memory, volatile memory, non-volatile memory; optical storage such as CD, DVD; removable media such as flash memory (e.g.
  • RAM random access memory
  • mass storage typically for more permanent storage, such as optical discs, forms of magnetic storage like hard disks, tapes, drums, cards and other types
  • processor registers cache memory, volatile memory, non-volatile memory
  • optical storage such as CD, DVD
  • removable media such as flash memory (e.g.
  • USB sticks or keys floppy disks, magnetic tape, paper tape, punch cards, standalone RAM disks, Zip drives, removable mass storage, off-line, and the like; other computer memory such as dynamic memory, static memory, read/write storage, mutable storage, read only, random access, sequential access, location addressable, file addressable, content addressable, network attached storage, storage area network, bar codes, magnetic ink, and the like.
  • the methods and systems described herein may transform physical and/or or intangible items from one state to another.
  • the methods and systems described herein may also transform data representing physical and/or intangible items from one state to another.
  • machines may include, but may not be limited to, personal digital assistants, laptops, personal computers, mobile phones, other handheld computing devices, medical equipment, wired or wireless communication devices, transducers, chips, calculators, satellites, tablet PCs, electronic books, gadgets, electronic devices, devices haa sender-controlled contact media content item artificial intelligence, computing devices, networking equipment, servers, routers and the like.
  • the elements depicted in the flow chart and block diagrams or any other logical component may be implemented on a machine capable of executing program instructions.
  • the methods and/or processes described above, and steps associated therewith, may be realized in hardware, software or any combination of hardware and software suitable for a particular application.
  • the hardware may include a general- purpose computer and/or dedicated computing device or specific computing device or particular aspect or component of a specific computing device.
  • the processes may be realized in one or more microprocessors, microcontrollers, embedded microcontrollers, programmable digital signal processors or other programmable device, along with internal and/or external memory.
  • the processes may also, or instead, be embodied in an application specific integrated circuit, a programmable gate array, programmable array logic, or any other device or combination of devices that may be configured to process electronic signals. It will further be appreciated that one or more of the processes may be realized as a computer executable code capable of being executed on a machine -readable medium.
  • the computer executable code may be created using a structured programming language such as C, an object oriented programming language such as C++, or any other high- level or low-level programming language (including assembly languages, hardware description languages, and database programming languages and technologies) that may be stored, compiled or interpreted to run on one of the above devices, as well as heterogeneous combinations of processors, processor architectures, or combinations of different hardware and software, or any other machine capable of executing program instructions.
  • a structured programming language such as C
  • an object oriented programming language such as C++
  • any other high- level or low-level programming language including assembly languages, hardware description languages, and database programming languages and technologies
  • methods described above and combinations thereof may be embodied in computer executable code that, when executing on one or more computing devices, performs the steps thereof.
  • the methods may be embodied in systems that perform the steps thereof, and may be distributed across devices in a number of ways, or all of the functionality may be integrated into a dedicated, standalone device or other hardware.
  • the means for performing the steps associated with the processes described above may include any of the hardware and/or software described above. All such permutations and combinations are intended to fall within the scope of the present disclosure.

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  • Radar, Positioning & Navigation (AREA)
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  • Computer Networks & Wireless Communication (AREA)
  • General Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
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Abstract

L'invention concerne un procédé comprenant les étapes consistant : à accéder à un ensemble de données comprenant un nuage de points acquis par LIDAR comprenant une pluralité de points à chacun desquels est attribuée au moins une coordonnée géospatiale, à sous-échantillonner au moins une partie de la pluralité de points en vue d'obtenir un échantillon représentatif de la pluralité de points et d'afficher l'échantillon représentatif de la pluralité de points.
EP17860192.8A 2016-10-11 2017-10-10 Scanner laser à estimation d'égo-mouvement en ligne en temps réel Pending EP3526626A4 (fr)

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PCT/US2017/055938 WO2018071416A1 (fr) 2016-10-11 2017-10-10 Scanner laser à estimation d'égo-mouvement en ligne en temps réel

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