CN113495256A - Method and device for determining accuracy of calibration results among multiple laser radars - Google Patents
Method and device for determining accuracy of calibration results among multiple laser radars Download PDFInfo
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Abstract
The invention discloses a method and a device for determining the accuracy of a calibration result among a plurality of laser radars, and relates to the field of sensors. One embodiment of the method comprises the steps of: acquiring point cloud data acquired by a plurality of laser radars on a scene containing a flat surface; converting point cloud data acquired by a plurality of laser radars into the same coordinate system by using a calibration result; respectively fitting an equation representing a flat surface based on the point cloud data of each laser radar; and calculating a value characterizing the accuracy of the calibration result using a plurality of equations. This embodiment achieves the effect of numerically representing the accuracy of the calibration result simply and intuitively.
Description
Technical Field
The invention relates to the field of sensors, in particular to a method and a device for determining the accuracy of a calibration result among a plurality of laser radars.
Background
In recent years, laser radars are increasingly used in the fields of transportation, national defense safety and the like. For example, in the related art, a laser radar is installed on an automobile and external information is acquired using the laser radar to assist a driver in driving, or to perform automatic driving.
Due to the fact that the vehicle is shielded and the blind areas of the laser radars exist, an independent laser radar sensor cannot normally complete tasks, and a plurality of laser radars are required to be installed on the vehicle to mutually compensate the blind areas. The coordinate relation among different laser radars is a key for fusing point cloud data of a plurality of laser radars together, and currently, a plurality of calibration methods exist. The calibration refers to a process of converting point cloud data acquired by a plurality of radars into the same coordinate system through coordinate conversion (using a rotation matrix and a translation vector or using a homogeneous matrix).
In the process of implementing the invention, the inventor finds that at least the following problems exist in the prior art: the existing calibration processing method and device cannot conveniently and accurately know the accuracy of the calibration result after the calibration is completed, and if the calibration result is not accurate, the situation that even though the calibration result is used for converting point cloud data acquired by a plurality of laser radars, the point cloud data cannot be well fused can occur.
Disclosure of Invention
In view of this, embodiments of the present invention provide a method and an apparatus for determining accuracy of calibration results among a plurality of laser radars, which can determine accuracy of the calibration results by using a flat surface (ground) existing in a scene, without arranging a special prop for determining accuracy of the calibration results in the scene, and at the same time, since accuracy of the calibration results of each laser radar is expressed in a form of a numerical value, the method and the apparatus are simple and intuitive, so that a user can conveniently and quickly know accuracy of the calibration results, and meanwhile, a calculation amount is reduced.
To achieve the above object, according to an aspect of an embodiment of the present invention, there is provided a method for determining accuracy of calibration results between a plurality of laser radars, including the steps of:
acquiring point cloud data acquired by a plurality of laser radars on a scene containing a flat surface;
converting the point cloud data acquired by the plurality of laser radars into the same coordinate system by using a calibration result;
respectively fitting an equation for representing the flat surface based on the point cloud data of each laser radar converted into the same coordinate system; and
and calculating a numerical value representing the accuracy of the calibration result by using a plurality of the equations.
In the method of determining the accuracy of the calibration results between a plurality of lidar units, preferably,
selecting one laser radar as a reference laser radar, using a coordinate system of the laser radar as a reference coordinate system, and converting point cloud data which is acquired by non-reference laser radars except the reference laser radar and is based on a self coordinate system into the reference coordinate system by using the calibration result;
fitting a reference plane equation characterizing the flat surface based on the point cloud data of the reference lidar, fitting a non-reference plane equation characterizing the flat surface based on the converted point cloud data of the non-reference lidar, the reference plane equation indicating a reference fit plane corresponding to the flat surface measured by the reference lidar, the non-reference plane equation indicating a non-reference fit plane corresponding to the flat surface measured by the non-reference lidar.
In the method of determining the accuracy of the calibration results between a plurality of lidar further preferably,
calculating the distance from the point in the non-reference fitting plane in the point cloud data acquired by the non-reference laser radar to the reference fitting plane,
and characterizing the accuracy of the calibration result by using the distance.
In the method of determining the accuracy of the calibration results between a plurality of lidar, it is further preferred,
calculating an average distance of distances from points in the non-reference fitting plane to the reference fitting plane in the point cloud data acquired by the non-reference laser radar,
and characterizing the accuracy of the calibration result by using the average distance.
In the method of determining the accuracy of the calibration results between a plurality of lidar further preferably,
calculating an angle between the normal of the non-reference fitting plane and the normal of the reference fitting plane,
and representing the accuracy of the calibration result by using the included angle.
In the method of determining the accuracy of the calibration results between a plurality of lidar units, preferably,
acquiring a plurality of frames of point cloud data acquired by the laser radar, and respectively fitting the datum plane equation representing the flat surface and the non-datum plane equation to each frame of point cloud data;
calculating the value characterizing the accuracy of the calibration result using the reference plane equation and the non-reference plane equation obtained from each frame of the point cloud data.
In the method of determining the accuracy of the calibration results between a plurality of lidar units, preferably,
selecting the laser radar that is highest in position among the plurality of laser radars as the reference laser radar.
According to another aspect of the embodiments of the present invention, there is provided an apparatus for determining accuracy of calibration results between a plurality of laser radars,
the disclosed device is provided with:
the data acquisition unit is used for acquiring point cloud data acquired by a plurality of laser radars on a scene comprising a flat surface;
the data conversion unit is used for converting the point cloud data acquired by the plurality of laser radars into the same coordinate system by using a calibration result;
the fitting unit is used for respectively fitting an equation representing the flat surface based on the point cloud data of each laser radar converted into the same coordinate system; and
a calculation unit that calculates a numerical value that characterizes an accuracy of the calibration result using a plurality of the equations.
There is also provided, in accordance with another aspect of an embodiment of the present invention, an electronic device that determines accuracy of calibration results between a plurality of laser radars, including:
one or more processors;
a storage device for storing one or more programs,
when executed by the one or more processors, cause the one or more processors to implement the method as described above.
According to another aspect of embodiments of the present invention, there is also provided a computer readable medium, on which a computer program is stored, characterized in that the program, when executed by a processor, implements the method as described above.
One embodiment of the above invention has the following advantages or benefits: because the accuracy of the calibration result is determined by utilizing the flat surface (ground) existing in the scene, special props for determining the accuracy of the calibration result do not need to be arranged in the scene, and meanwhile, the accuracy of the calibration result of each laser radar is expressed in a numerical form, so that the method is simple and intuitive. The user can conveniently and quickly know the accuracy of the calibration result, and meanwhile, the calculation amount is reduced.
Further effects of the above-mentioned non-conventional alternatives will be described below in connection with the embodiments.
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The drawings are included to provide a better understanding of the invention and are not to be construed as unduly limiting the invention. Wherein:
FIG. 1 is a schematic diagram of the main steps of a first embodiment of a method of determining the accuracy of calibration results between a plurality of lidar in accordance with the present invention;
FIG. 2 is a schematic diagram of the main steps of a second embodiment of the method of determining the accuracy of calibration results between a plurality of lidar according to the invention;
FIG. 3 is a schematic diagram of the main modules of an apparatus for determining the accuracy of calibration results between multiple lidar in accordance with an embodiment of the invention;
fig. 4 is a schematic block diagram of a computer system suitable for use in implementing a terminal device or server of an embodiment of the invention.
Detailed Description
Exemplary embodiments of the present invention are described below with reference to the accompanying drawings, in which various details of embodiments of the invention are included to assist understanding, and which are to be considered as merely exemplary. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the embodiments described herein can be made without departing from the scope and spirit of the invention. Also, descriptions of well-known functions and constructions are omitted in the following description for clarity and conciseness.
(first embodiment)
The method for determining the accuracy of the calibration result among the plurality of laser radars is used for determining the accuracy of the calibration result among the plurality of vehicle-mounted multiline laser radars.
Fig. 1 illustrates a method for determining accuracy of calibration results between a plurality of lidar according to an embodiment of the present invention, and as shown in fig. 1, the method for determining accuracy of calibration results between a plurality of lidar according to an embodiment of the present invention achieves an effect of simply and intuitively representing accuracy of calibration results by numerical values.
Fig. 1 shows a method for determining accuracy of calibration results between a plurality of lidar according to an embodiment of the present invention, which includes a data acquisition step S101 of standing a vehicle mounted with a plurality of multiline lidar on a flat ground and acquiring point cloud data collected by three multiline lidar on a scene. The point cloud data refers to data recorded in the form of points, each of which includes three-dimensional coordinates.
In this embodiment, the vehicle has three multiline lidar, and therefore, the point cloud data of three lidar is collected in total, but the number of lidar is not limited.
It is understood that in the present invention, the vehicle does not have to be left standing on the ground, and the object of the present invention can be achieved in a scene having a flat surface. For example, a scene with a wall in front of the vehicle may be selected.
The method for determining the accuracy of the calibration result among the plurality of laser radars according to one embodiment of the present invention has a data conversion step S102, in which one laser radar with the highest height is selected as a reference laser radar, a coordinate system of the reference laser radar is used as a reference coordinate system, and point cloud data based on the coordinate system thereof, which are acquired by the other two laser radars (non-reference laser radars), is converted into the reference coordinate system through the calibration result.
The specific form of the calibration result is a rotation matrix R and a translation vector (x, y, z).
(in the rotation matrix R, ψ is a roll angle),
Pitch (pitch angle) and θ yaw (yaw angle)). Using the rotation matrix and translation vector, the coordinates of the point in one coordinate system can be converted to coordinates in another coordinate system. In the embodiment, the coordinates of the point cloud data based on the self coordinate system acquired by the non-reference laser radar are converted into the coordinate system of the reference laser radar.
The calibration result can also be a homogeneous matrix M1And (4-4 matrix), and the rotation and translation of the coordinates can be simultaneously completed by using the homogeneous matrix, so that the coordinates of the point in one coordinate system are converted into other coordinate systems, and the specific calculation formula is as follows.
In this formula, the coordinates (X) of a point in a coordinate systemW，YW，XW) Converted into the coordinates (X) of the point in another coordinate systemC，YC，ZC). The calculation process when the rotation matrix R and the translation vector are used is similar to this, and therefore, the explanation is omitted。
That is, the coordinates of the point cloud data based on the coordinate system of the laser radar acquired by one laser radar can be converted into the coordinates of the coordinate system based on the other laser radar, and in the present embodiment, the coordinates are converted into the coordinates in the coordinate system of the reference laser radar.
The accuracy of the calibration result between a plurality of laser radars is determined by determining whether the parameters in the matrixes (a rotation matrix and a translation vector or a homogeneous matrix) are accurate. When the calibration result is found to be inaccurate, the operator recalibrates the calibration according to the requirement.
It should be noted that, although the embodiment of the present invention is described with a case where one lidar is selected as the reference lidar and the other lidar is selected as the non-reference lidar, it should be understood that this is merely an illustrative description and is not to be construed in a limiting manner. For example, the laser radar may be numbered as a first laser radar, a second laser radar, or the like, without affecting the effect of the present invention.
In the fitting step S103, the ground is extracted from the point cloud data acquired by the reference lidar, and the ground is fitted using the RANSAC algorithm, resulting in a first plane equation (hereinafter referred to as "reference plane equation") expressed as A1X + B1Y + C1Z + D1 being 0. The reference plane equation represents a fitting plane of the point cloud data of the reference lidar to the ground, i.e., a reference fitting plane.
Wherein a1, B1, C1, D1 are parameters of the first plane equation, respectively, i.e., a reference fitting plane is completely determined from the four parameters.
Next, the ground is extracted from the point cloud data collected by the non-reference lidar which has been converted in the data conversion step S102, and the ground is fitted using the RANSAC algorithm, resulting in non-reference plane equations expressed as A2X + B2Y + C2Z + D2 ═ 0 (second plane equation) and A3X + B3Y + C3Z + D3 ═ 0 (third plane equation). The non-reference plane equation represents a fitting plane to the ground by the point cloud data of the non-reference lidar, i.e., a non-reference fitting plane (a second fitting plane and a third fitting plane). Wherein a2, B2, C2, D2 are parameters of the second plane equation, respectively, from which a second fitted plane is completely determined; a3, B3, C3, D3 are the parameters of the third plane equation, respectively, from which the third plane of fit is completely determined.
Here, since the vehicle has three lidar, one reference plane equation and two non-reference plane equations are obtained, but in the case where the vehicle has two or more lidar, the number of plane equations may also be changed. For example, with five lidar, one reference plane equation and four non-reference plane equations may be obtained.
The RANSAC algorithm is a Random Sample Consensus (Random Sample Consensus) algorithm, which is an algorithm for obtaining effective Sample data by calculating mathematical model parameters of data according to a Sample data set containing abnormal data. The basic assumption of the RANSAC algorithm is that samples contain correct data (inliers, data that can be described by a model) and also contain abnormal data (outliers, data that is far from a normal range and cannot adapt to a mathematical model), that is, data sets contain noise. These outlier data may be due to erroneous measurements, erroneous assumptions, erroneous calculations, etc.
In the calculation step S104, numerical processing is performed using the reference plane equation and the non-reference plane equation. Specifically, an included angle between the normal lines of the two non-reference fitting planes and the normal line of the reference fitting plane is calculated respectively. In the present embodiment, since two non-reference laser radars are used in common, the angle between the normal lines of the two non-reference fitting planes and the normal line of the reference fitting plane is calculated in common. The calculation formula of the included angle between the normal line of the second fitting plane and the normal line of the reference fitting plane is as follows:
the angle between the normal of the third fitting plane and the normal of the reference fitting plane is calculated by replacing a2, B2, C2, D2 in the above formula with A3, B3, C3, D3.
It is understood that in the present invention, it is not necessary to select the laser radar with the highest height as the reference laser radar, and the object of the present invention can be achieved by selecting any one of the laser radars as the reference laser radar. In the embodiment of the present invention, the laser radar at the highest position may be automatically selected as the reference laser radar, or may be appropriately selected by the operator according to the actual situation.
In the present embodiment, the description is given of the form of calculating the angle between the normal line of the non-reference fitting plane and the normal line of the reference fitting plane, but the angle between each fitting plane and another fitting plane may be calculated. For example, in the case of three lidar in this embodiment, the angle of each fitting plane relative to the other two fitting planes may be calculated separately.
In this embodiment, an alarm step S105 is provided to determine whether each included angle is greater than a threshold value by 0.5 °, and when an included angle greater than 0.5 ° exists between the two included angles, an alarm is given to the outside to remind an operator that the calibration results of the plurality of laser radars are not qualified. The operator can recalibrate as needed.
The threshold value may be appropriately selected according to the required calibration accuracy and the flatness of the ground, and is not limited to 0.5 °, for example, when the required calibration accuracy is high, the threshold value may be set to 0.2 °, that is, when an included angle greater than 0.2 ° exists between the two included angles, an alarm is issued to the outside.
In addition, the calculated angle may be directly output to the outside without setting the threshold, and the operator may determine whether the calibration result is acceptable.
The method for determining the accuracy of the calibration result among the plurality of laser radars in the embodiment does not need to arrange a special prop for determining the accuracy of the calibration result in a scene, but utilizes a flat surface (ground) existing in the scene to determine the accuracy of the calibration result. Moreover, because the difference of the fitting planes of the laser radars is expressed in the form of an included angle, the method is simple and intuitive, the calculated amount is less, and the occupied resources in the calculation process are reduced. The user can conveniently and quickly know the quality of the calibration result.
(modification 1)
The method for determining the calibration result of the point cloud data in the single frame has the advantages that a large error exists when the calibration result is judged according to the fitting plane fitted by the point cloud data in the single frame, and the calibration result is easily influenced by accidents, so that an error exists in the accuracy of the determined calibration result, and the like.
As an improvement of the first embodiment of the present invention, in the data acquiring step, multiple frames of point cloud data acquired by multiple laser radars are acquired, and a fitting plane is obtained by the same laser radar according to each frame of point cloud data. I.e. each lidar is fitted with a number of fitting planes (corresponding to the number of frames).
Because a plurality of fitting planes are fitted according to the point cloud data acquired by each laser radar, two included angles are formed between the normal lines of the two non-reference fitting planes and the normal line of the reference fitting plane for the content in each frame.
In modification 1, it is set that only when the value of two included angles in the number of frames greater than 80% is greater than 0.5 °, an alarm is issued to the outside to remind the operator that the calibration results of the plurality of laser radars are not qualified. The proportion of the number of frames can be selected according to the needs, or can be set to be more than 50% (determined according to the actual situation) when the value of two included angles in the number of frames is more than 0.5 degrees (not limited, can be determined according to the situation), the alarm is sent to the outside.
According to the technical scheme of the modification 1, the accuracy of the calibration result among the plurality of laser radars is determined by acquiring the multi-frame point cloud data acquired by the plurality of laser radars, so that the influence of accidental factors or errors can be avoided as much as possible.
(second embodiment)
The second embodiment of the present invention is different from the first embodiment described above in that, in the calculation step S204, the distance from a point located in a non-reference plane in the point cloud data acquired by the non-reference laser radar to the reference fitting plane is calculated using a point-to-plane distance equation, and the average distance of these distances is obtained. The magnitude of the average distance represents the magnitude of the difference between the non-reference fit plane and the reference fit plane, and therefore the average distance is used to represent the accuracy of the calibration results. The other steps (data acquisition step S201, data conversion step S202, and fitting step S203) are the same as those in the first embodiment, and therefore, the description thereof is omitted.
In the calculation step of this embodiment, in the calculation step S204, the distance (within the laser radar range) from the point (the point excluding the fitting plane not participating in the fitting plane) actually located on the second fitting plane (A2X + B2Y + C2Z + D2 ═ 0) to the reference fitting plane (A1X + B1Y + C1Z + D1 ═ 0) as the first fitting plane is calculated, and the average distance D1 is obtained. In the same manner, the average distance D2 from the point on the third fitting plane (A3X + B3Y + C3Z + D3 ═ 0) to the reference fitting plane (A1X + B1Y + C1Z + D1 ═ 0) was determined.
Since the RANSAC algorithm is used in the fitting step, in the calculating step, data that is too far from the normal range is not involved in the calculation (i.e., points that do not participate in the fitting plane are eliminated) in calculating the distance.
After the average distances d1 and d2 are obtained, it is determined whether the average distances d1 and d2 are greater than the threshold value of 0.05 m. And when the conditions of more than 0.05m exist in d1 and d2, giving an alarm to the outside to remind an operator that the calibration results of the plurality of laser radars are unqualified. The threshold value may be appropriately selected according to the required calibration accuracy and the flatness of the ground, and is not limited to 0.05 m. In addition, the calculated average distance may be directly output to the outside without setting the threshold, and the operator may determine whether the calibration result is acceptable.
It is to be understood that, although the accuracy of the calibration results of the plurality of lidar is characterized by the average distance in the present embodiment, a distance such as a median may be selected from distances from points (excluding points not participating in the fitting plane) actually located on the non-reference fitting plane (A2X + B2Y + C2Z + D2 ═ 0) to the reference fitting plane, i.e., the reference fitting plane (A1X + B1Y + C1Z + D1 ═ 0) to characterize the accuracy of the calibration results of the plurality of lidar.
The second embodiment is simple and intuitive because the difference of the fitting planes of the respective laser radars is expressed in the form of distance. The user can conveniently and quickly know the quality of the calibration result.
(modification 2)
Similar to modification 1, as an improvement of the second embodiment of the present invention, in the data acquisition step, multiple frames of point cloud data acquired by multiple lidar are acquired, and one fitting plane is obtained by the same lidar according to each frame of point cloud data. I.e. each lidar is fitted with a number of fitting planes (corresponding to the number of frames).
Since a plurality of fitting planes are fitted to the point cloud data acquired by each laser radar, the distance from a point located on a non-reference fitting plane (excluding points not participating in the fitting plane) to the reference fitting plane is calculated for the content in each frame at this time, and the average distances d1 and d2 are obtained.
In modification 2, it is set that only when the values of two distances among the number of frames greater than 80% are greater than 0.05m, an alarm is issued to the outside to alert an operator that the calibration results of the plurality of laser radars are not qualified. The ratio of the number of frames is not limited, and it may be set such that when the value of the average distance between two frames is greater than 0.05m (which is not limited, and may be determined according to the situation) among the number of frames greater than 50% (which is determined according to the actual situation), an alarm is issued to the outside.
The modification 2 determines the accuracy of the calibration result among the plurality of laser radars by acquiring multi-frame point cloud data acquired by the plurality of laser radars, so that the influence of accidental factors or errors can be avoided as much as possible.
(third embodiment)
As a third embodiment of the present invention, an angle between a normal of the non-reference fitting plane and a normal of the reference fitting plane and a distance from a point in the non-reference fitting plane to the reference fitting plane may be simultaneously used as numerical values representing accuracy of the calibration result.
In this case, since there are two kinds of data, the operator can determine the accuracy of the calibration result more clearly from two aspects.
(fourth embodiment)
A fourth embodiment of the present invention provides an apparatus for determining accuracy of calibration results between a plurality of laser radars, including: the device comprises a data acquisition unit 1, a data conversion unit 2, a fitting unit 3 and a calculation unit 4.
In the present embodiment, the data acquisition unit 1 acquires point cloud data acquired by three laser radars for a scene including a flat surface.
The data conversion unit 2 selects a laser radar with the highest position from the three laser radars as a reference laser radar, and converts point cloud data which are acquired by the remaining two non-reference laser radars and are based on a self coordinate system into a reference coordinate system through an acquired calibration result.
The fitting unit 3 fits a reference plane equation and a non-reference plane equation representing the ground based on the point cloud data of the reference laser radar and the point cloud data of the non-reference laser radar after conversion, the reference plane equation indicates a reference fitting plane, and the non-reference plane equation indicates a non-reference fitting plane. Wherein a reference fit plane corresponds to the flat surface measured by the reference lidar and a non-reference fit plane corresponds to the flat surface measured by the non-reference lidar.
The calculation unit 4 performs numerical processing by using the reference plane equation and the non-reference plane equation to obtain a numerical value representing the accuracy of the calibration result. Specifically, the calculation unit respectively calculates included angles between the normals of the two non-reference fitting planes and the normal of the reference fitting plane, and the included angles are used for representing the difference between the non-reference fitting planes and the reference fitting plane, so that the accuracy of the calibration result among the plurality of laser radars is determined.
The calculation unit can also respectively calculate the distance between a point in the non-reference fitting plane and the reference fitting plane in the point cloud data acquired by the non-reference laser radar, so as to calculate the average distance, and the average distance is used for representing the difference between the non-reference fitting plane and the reference fitting plane, so that the accuracy of the calibration result among the plurality of laser radars is determined.
In the present embodiment, the apparatus for determining the accuracy of the calibration results between the plurality of laser radars further includes an output unit 5 for outputting the angle or the average distance to the outside, so that the operator can intuitively know the accuracy of the calibration results.
In the present embodiment, an alarm unit 6 is provided, and the alarm unit 6 is provided with a threshold value, and when the included angle or the average distance is larger than the threshold value, the alarm unit 6 gives an alarm indicating that the calibration result is not acceptable to the outside. The threshold value may be set as appropriate depending on the required accuracy and the circumstances of the surrounding environment, and may be, for example, an angle value of 0.5 °, or may be set to an angle value of 0.2 ° or an average distance of 0.05m when higher accuracy is required. The alarm output to the outside may comprise an excess of the angle or average distance compared to a threshold, or only an indication that the calibration result is not acceptable.
The apparatus for determining the accuracy of calibration results among a plurality of laser radars of the fourth embodiment may make it unnecessary to arrange a special prop for determining the accuracy of calibration results in a scene, but make use of a flat surface (ground) existing in the scene to determine the accuracy of calibration results. Moreover, the accuracy of the calibration result of each laser radar can be expressed in a data form, so that the method is simple and intuitive. The user can conveniently and quickly know the quality of the calibration result, and meanwhile, the calculation amount is reduced.
The method and apparatus for determining the accuracy of the calibration results between a plurality of lidar of the present invention are applied to the vehicle-mounted multiline lidar, but the present invention is not limited thereto, and may be applied to the fields of, for example, airplanes, ships, and the like.
Referring now to FIG. 4, a block diagram of a computer system 400 suitable for use with a terminal device implementing an embodiment of the invention is shown. The terminal device shown in fig. 4 is only an example, and should not bring any limitation to the functions and the scope of use of the embodiments of the present invention.
As shown in fig. 4, the computer system 400 includes a Central Processing Unit (CPU)401 that can perform various appropriate actions and processes in accordance with a program stored in a Read Only Memory (ROM)402 or a program loaded from a storage section 408 into a Random Access Memory (RAM) 403. In the RAM 403, various programs and data necessary for the operation of the system 400 are also stored. The CPU 401, ROM 402, and RAM 403 are connected to each other via a bus 404. An input/output (I/O) interface 405 is also connected to bus 404.
The following components are connected to the I/O interface 405: an input section 406 including a keyboard, a mouse, and the like; an output section 407 including a display device such as a Cathode Ray Tube (CRT), a Liquid Crystal Display (LCD), and the like, and a speaker; a storage section 408 including a hard disk and the like; and a communication section 409 including a network interface card such as a LAN card, a modem, or the like. The communication section 409 performs communication processing via a network such as the internet. A driver 410 is also connected to the I/O interface 405 as needed. A removable medium 411 such as a magnetic disk, an optical disk, a magneto-optical disk, a semiconductor memory, or the like is mounted on the drive 410 as necessary, so that a computer program read out therefrom is mounted into the storage section 408 as necessary.
In particular, according to the embodiments of the present disclosure, the processes described above with reference to the flowcharts may be implemented as computer software programs. For example, embodiments of the present disclosure include a computer program product comprising a computer program embodied on a computer readable medium, the computer program comprising program code for performing the method illustrated in the flow chart. In such an embodiment, the computer program may be downloaded and installed from a network through the communication section 409, and/or installed from the removable medium 411. The computer program performs the above-described functions defined in the system of the present invention when executed by a Central Processing Unit (CPU) 401.
It should be noted that the computer readable medium shown in the present invention can be a computer readable signal medium or a computer readable storage medium or any combination of the two. A computer readable storage medium may be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination of the foregoing. More specific examples of the computer readable storage medium may include, but are not limited to: an electrical connection having one or more wires, a portable computer diskette, a hard disk, a Random Access Memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. In the present invention, a computer readable storage medium may be any tangible medium that can contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device. In the present invention, however, a computer readable signal medium may include a propagated data signal with computer readable program code embodied therein, for example, in baseband or as part of a carrier wave. Such a propagated data signal may take many forms, including, but not limited to, electro-magnetic, optical, or any suitable combination thereof. A computer readable signal medium may also be any computer readable medium that is not a computer readable storage medium and that can communicate, propagate, or transport a program for use by or in connection with an instruction execution system, apparatus, or device. Program code embodied on a computer readable medium may be transmitted using any appropriate medium, including but not limited to: wireless, wire, fiber optic cable, RF, etc., or any suitable combination of the foregoing.
The flowchart and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods and computer program products according to various embodiments of the present invention. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical function(s). It should also be noted that, in some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams or flowchart illustration, and combinations of blocks in the block diagrams or flowchart illustration, can be implemented by special purpose hardware-based systems which perform the specified functions or acts, or combinations of special purpose hardware and computer instructions.
The units described in the embodiments of the present invention may be implemented by software or hardware. The described units may also be provided in a processor, and may be described as: a processor comprising: the device comprises a data acquisition unit, a data conversion unit, a fitting unit and a calculation unit. The names of the units do not in some cases form a limitation on the units themselves, and for example, the data acquisition unit may also be described as a "unit that acquires point cloud data acquired by a lidar".
As another aspect, the present invention also provides a computer-readable medium that may be contained in the apparatus described in the above embodiments; or may be separate and not incorporated into the device. The computer readable medium carries one or more programs which, when executed by a device, cause the device to include the steps of:
acquiring point cloud data acquired by a plurality of laser radars on a scene containing a flat surface;
converting the point cloud data acquired by the plurality of laser radars into the same coordinate system by using a calibration result;
fitting an equation representing the flat surface based on the point cloud data of each laser radar; and
and calculating a numerical value representing the accuracy of the calibration result by using a plurality of the equations.
According to the technical scheme of the embodiment of the invention, a special prop for determining the accuracy of the calibration result is not required to be arranged in the scene, and the accuracy of the calibration result is determined by utilizing a flat surface (ground) existing in the scene. And the accuracy of the fitting result of each laser radar is expressed in a numerical form, so that the method is simple and intuitive, the calculation amount is small, and the occupied resources in the calculation process are reduced. The user can conveniently and quickly know the quality of the calibration result.
The above-described embodiments should not be construed as limiting the scope of the invention. Those skilled in the art will appreciate that various modifications, combinations, sub-combinations, and substitutions can occur, depending on design requirements and other factors. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. A method of determining the accuracy of calibration results between a plurality of lidar comprising the steps of:
acquiring point cloud data acquired by a plurality of laser radars on a scene containing a flat surface;
converting the point cloud data acquired by the plurality of laser radars into the same coordinate system by using a calibration result;
respectively fitting an equation for representing the flat surface based on the point cloud data of each laser radar converted into the same coordinate system; and
and calculating a numerical value representing the accuracy of the calibration result by using a plurality of the equations.
2. The method of determining accuracy of calibration results between a plurality of lidar according to claim 1,
selecting one laser radar as a reference laser radar, using a coordinate system of the laser radar as a reference coordinate system, and converting point cloud data which is acquired by non-reference laser radars except the reference laser radar and is based on a self coordinate system into the reference coordinate system by using the calibration result;
fitting a reference plane equation characterizing the flat surface based on the point cloud data of the reference lidar, fitting a non-reference plane equation characterizing the flat surface based on the converted point cloud data of the non-reference lidar, the reference plane equation indicating a reference fit plane corresponding to the flat surface measured by the reference lidar, the non-reference plane equation indicating a non-reference fit plane corresponding to the flat surface measured by the non-reference lidar.
3. The method of determining accuracy of calibration results between a plurality of lidar according to claim 2,
calculating the distance from the point in the non-reference fitting plane in the point cloud data acquired by the non-reference laser radar to the reference fitting plane,
and characterizing the accuracy of the calibration result by using the distance.
4. The method of determining accuracy of calibration results between a plurality of lidar according to claim 3,
calculating an average distance of distances from points in the non-reference fitting plane to the reference fitting plane in the point cloud data acquired by the non-reference laser radar,
and characterizing the accuracy of the calibration result by using the average distance.
5. The method of determining accuracy of calibration results between a plurality of lidar according to claim 2,
calculating an angle between the normal of the non-reference fitting plane and the normal of the reference fitting plane,
and representing the accuracy of the calibration result by using the included angle.
6. The method of determining accuracy of calibration results between a plurality of lidar according to any of claims 2-5,
acquiring a plurality of frames of point cloud data acquired by the laser radar, and respectively fitting the datum plane equation representing the flat surface and the non-datum plane equation to each frame of point cloud data;
calculating the value characterizing the accuracy of the calibration result using the reference plane equation and the non-reference plane equation obtained from each frame of the point cloud data.
7. The method of determining accuracy of calibration results between a plurality of lidar according to any of claims 2-5,
selecting the laser radar that is highest in position among the plurality of laser radars as the reference laser radar.
8. An apparatus for determining accuracy of calibration results between a plurality of lidar comprising:
the data acquisition unit is used for acquiring point cloud data acquired by a plurality of laser radars on a scene comprising a flat surface;
the data conversion unit is used for converting the point cloud data acquired by the plurality of laser radars into the same coordinate system by using a calibration result;
the fitting unit is used for respectively fitting an equation representing the flat surface based on the point cloud data of each laser radar converted into the same coordinate system; and
a calculation unit that calculates a numerical value that characterizes an accuracy of the calibration result using a plurality of the equations.
9. An electronic device for determining accuracy of calibration results between a plurality of lidar comprising:
one or more processors;
a storage device for storing one or more programs,
when executed by the one or more processors, cause the one or more processors to implement the method of any one of claims 1-5.
10. A computer-readable medium, on which a computer program is stored, which, when being executed by a processor, carries out the method according to any one of claims 1-5.
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