CN110335308A - The binocular vision speedometer calculation method examined based on disparity constraint and two-way annular - Google Patents

The binocular vision speedometer calculation method examined based on disparity constraint and two-way annular Download PDF

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CN110335308A
CN110335308A CN201910578572.0A CN201910578572A CN110335308A CN 110335308 A CN110335308 A CN 110335308A CN 201910578572 A CN201910578572 A CN 201910578572A CN 110335308 A CN110335308 A CN 110335308A
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characteristic point
moment
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point
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CN110335308B (en
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汤淑明
黄馨
张力夫
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Institute of Automation of Chinese Academy of Science
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    • GPHYSICS
    • G01MEASURING; TESTING
    • G01CMEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
    • G01C21/00Navigation; Navigational instruments not provided for in groups G01C1/00 - G01C19/00
    • G01C21/20Instruments for performing navigational calculations
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01CMEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
    • G01C22/00Measuring distance traversed on the ground by vehicles, persons, animals or other moving solid bodies, e.g. using odometers, using pedometers
    • GPHYSICS
    • G06COMPUTING; CALCULATING OR COUNTING
    • G06TIMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T7/00Image analysis
    • G06T7/70Determining position or orientation of objects or cameras
    • GPHYSICS
    • G06COMPUTING; CALCULATING OR COUNTING
    • G06TIMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T7/00Image analysis
    • G06T7/70Determining position or orientation of objects or cameras
    • G06T7/73Determining position or orientation of objects or cameras using feature-based methods
    • G06T7/75Determining position or orientation of objects or cameras using feature-based methods involving models
    • GPHYSICS
    • G06COMPUTING; CALCULATING OR COUNTING
    • G06VIMAGE OR VIDEO RECOGNITION OR UNDERSTANDING
    • G06V10/00Arrangements for image or video recognition or understanding
    • G06V10/70Arrangements for image or video recognition or understanding using pattern recognition or machine learning
    • G06V10/74Image or video pattern matching; Proximity measures in feature spaces
    • G06V10/75Organisation of the matching processes, e.g. simultaneous or sequential comparisons of image or video features; Coarse-fine approaches, e.g. multi-scale approaches; using context analysis; Selection of dictionaries
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Abstract

The invention belongs to field of locating technology, more particularly to the binocular vision speedometer calculation method examined based on disparity constraint and two-way annular, it is intended that the accuracy rate of solution existing binocular vision speedometer feature association is low, and the low problem low with real-time of bring positioning accuracy.The method of the present invention includes: to carry out Image Acquisition by the binocular camera being loaded on mobile vehicle;Newly-increased feature point is obtained by Shi-Tomasi angular-point detection method to setting image and obtains new set of characteristic points;Characteristic point is tracked using KLT optical flow method, and the method by combining disparity constraint and adaptive two-way annular to examine establishes feature association;Estimated based on feature association as a result, obtaining initial pose using PNP method, and by characteristic point trigonometric ratio;Using light-stream adjustment, the final pose of the optimal estimation of pose is obtained by minimum re-projection error.The present invention improves the quality and efficiency of signature tracking, improves the positioning accuracy and real-time of binocular vision speedometer.

Description

The binocular vision speedometer calculation method examined based on disparity constraint and two-way annular
Technical field
The invention belongs to field of locating technology, and in particular to a kind of binocular vision examined based on disparity constraint with two-way annular Feel odometer calculation method.
Background technique
Intelligent vehicle receives each research institution, the world and colleges and universities as most active a part is developed in intelligent transportation system Pay close attention to.Location technology is one of the key technology of intelligent vehicle safety movement, is played in automatic Pilot field important Effect.
Binocular vision speedometer is a kind of practical vision positioning technology, and the pose of vehicle can be effectively estimated.With figure As the development of processing technique and calculation power, binocular vision speedometer is gradually applied in embedded system, and becomes the one of automatic Pilot A important component.Its advantage is that at low cost, energy consumption is small, easy for installation, good portability, anti-electromagnetic interference capability are strong Deng.
The key step of binocular vision speedometer is divided into feature association and pose estimation.Feature association be based on feature extraction and Tracking is established, and pose estimation is then based on feature association as a result, being obtained by minimizing re-projection error.Therefore, it establishes effective Feature association be highly important.Method general at present is examined using front and back and left and right is examined and obtained to optical flow tracking Feature association is tested, but this method still includes more exterior point, there are low-quality feature point tracking, precision and in real time Property needs to be further increased.
Summary of the invention
In order to solve the above problem in the prior art, in order to solve the standard of existing binocular vision speedometer feature association True rate is low, and the low problem low with real-time of bring positioning accuracy, first aspect present invention, proposes a kind of based on disparity constraint The binocular vision speedometer calculation method examined with two-way annular, this method comprises:
Step S100 carries out left hand view according to the frequency acquisition of setting by the binocular camera being loaded on mobile vehicle The acquisition of picture, image right, obtains the corresponding left-side images of t-1, t moment, image right;
Step S200 carries out Shi-Tomasi Corner Detection to the setting image at t-1 moment obtained in step S100, mentions It is new to construct the setting image for the characteristic point of the setting image for taking newly-increased feature point set, and obtaining in conjunction with the t-1 moment Set of characteristic points;
Step S300, based on the new set of characteristic points of the setting image, using KLT optical flow method, by disparity constraint and Adaptive two-way annular is examined, and obtains the corresponding set of characteristic points of other images of t-1, t moment respectively, and carry out feature pass Connection;
Step S400, based in step S300 feature association as a result, obtaining the movement using PNP position and orientation estimation method The initial pose of carrier is estimated, and carries out three to characteristic point each in t moment left-side images, image right by binocular vision method Angling obtains the corresponding three dimensional space coordinate of each characteristic point;
Step S500, result, the initial pose estimation, t moment left-side images, the right side based on step S300 feature association The three dimensional space coordinate of each characteristic point and two dimensional image coordinate in the image of side, using light-stream adjustment, by minimizing re-projection Error obtains the maximal possibility estimation of the pose of the mobile vehicle, obtains final pose.
In some preferred embodiments, left-side images collected, image right pass through OpenCV in step S100 Library function is corrected.
In some preferred embodiments, " characteristic point for the setting image that the t-1 moment obtains ", acquisition methods Are as follows:
At the t-1 moment, the binocular image at t-2, t-1 moment is obtained using the method tracking of step S200, step S300 The t-1 moment sets the characteristic point of image.
In some preferred embodiments, " newly-increased feature point set is extracted " in step S200, method are as follows:
The characteristic point of the setting image at t-1 moment is extracted by Shi-Tomasi angular-point detection method, and will be fallen into The feature point deletion of the primitive character point setting range neighborhood of the setting image, obtains newly-increased feature point;The setting image Primitive character be the characteristic point of the setting image obtained at the t-1 moment.
In some preferred embodiments, the left-side images for setting image and being acquired as t moment.
In some preferred embodiments, step S300 " obtains the corresponding feature of other images of t-1, t moment respectively Point set, and carry out feature association ", method are as follows:
By the left-side images at t-1 momentCharacteristic pointIt is tracked to obtain on a t moment left side by KLT optical flow method Side imageCharacteristic pointThe characteristic point that screening t-1 moment left-side images are examined by front and back, and establishWithSpy Sign association;
By t moment left-side imagesCharacteristic pointIt is tracked to obtain in t moment image right by KLT optical flow method On characteristic pointThe characteristic point with disparity constraint is examined by left and right, and is establishedWithFeature association;
It is by t moment image rightOn characteristic pointIt is tracked to obtain on the right side of the t-1 moment by KLT optical flow method ImageOn characteristic pointScreen t moment image rightPass through the adaptive rear preceding characteristic point examined.
In some preferred embodiments, " the corresponding spy of other images of t-1, t moment are obtained respectively in step S300 Levy point set ", it, will if t-1 is initial timeCharacteristic pointIt is tracked to obtain by KLT optical flow methodOn feature PointScreening obtains the characteristic point by left and right inspection and disparity constraint.
In some preferred embodiments, " screening obtains the characteristic point by left and right inspection and disparity constraint ", side Method are as follows:
It obtainsWithY-coordinate difference be less than given threshold ρ1Characteristic point, and by characteristic pointTraceback obtains ?On characteristic pointIfWithDistance be less than given threshold δ1, then examined by left and right.
In some preferred embodiments, " screening t-1 moment left-side images in step S301In pass through front and back examine The characteristic point tested ", method are as follows:
By characteristic pointTraceback obtainsOn characteristic point
IfWithDistance be less than given threshold δ2, then as the characteristic point examined by front and back.
In some preferred embodiments, " screening t moment left-side images in step S302It is examined and is regarded by left and right The characteristic point of difference constraint ", method are as follows:
If characteristic pointWithY-coordinate difference be less than given threshold ρ1, then retain this feature point and execute with lower section Otherwise case deletes this feature point;
By characteristic pointTraceback obtainsOn characteristic point
IfWithDistance be less than given threshold δ3, then as the characteristic point examined by left and right.
In some preferred embodiments, " screening t moment image right in step S303Pass through adaptive rear preceding inspection The characteristic point tested ", method are as follows:
By characteristic pointTraceback obtainsOn characteristic point
IfWithDistance be less than adaptive threshold δ4, then as the characteristic point by adaptive rear preceding inspection;
Wherein, adaptive threshold δ4Calculation method are as follows:
Wherein, ρ and ε is parameter, and loss is the characteristic point of t-1 moment image right feature point tracking t moment left-side images When with the characteristic point number lost, maxtrack is the maximum tracking number of current signature point.
In some preferred embodiments, " maximum of pose is obtained by minimizing re-projection error in step S500 Possibility predication ", method are as follows:
According to feature association as a result, to each characteristic point building space re-projection error and time weight on each picture frame Projection error;
The maximal possibility estimation of the pose in sliding window is obtained using light-stream adjustment.
In some preferred embodiments, further include step S600 after step S500:
Based on the final pose at moment each before t moment, t moment is obtained by marginalisation method and Shu Er decomposition method Priori item rp, and by the priori item rpPrior uncertainty as maximal possibility estimation in step S500.
A kind of the second aspect of the present invention, it is also proposed that binocular vision mileage examined based on disparity constraint with two-way annular Computing system is counted, which includes binocular image acquiring unit, initial characteristics point extraction unit, feature point extraction and feature association Unit, initial pose estimation unit, maximal possibility estimation unit;
The binocular image acquiring unit, is configured to the binocular camera by being loaded on mobile vehicle, according to setting Frequency acquisition carries out the acquisition of left-side images, image right, obtains the corresponding left-side images of t-1, t moment, image right;
The initial characteristics point extraction unit, was configured to the t-1 moment obtained in the binocular image acquiring unit It sets image and carries out Shi-Tomasi Corner Detection, the setting extracting newly-increased feature point set, and obtaining in conjunction with the t-1 moment The characteristic point of image constructs the new set of characteristic points of the setting image;
The feature point extraction and feature association unit are configured to make the set of characteristic points new based on the setting image, Using KLT optical flow method, is examined by disparity constraint and adaptive two-way annular, obtain other images pair of t-1, t moment respectively The set of characteristic points answered, and carry out feature association;
The initial pose estimation unit is configured to the feature association as a result, obtaining using PNP position and orientation estimation method The initial pose estimation of the mobile vehicle is obtained, and by binocular vision method to each spy in t moment left-side images, image right Sign point carries out trigonometric ratio, obtains the corresponding three dimensional space coordinate of each characteristic point;
The maximal possibility estimation unit is configured to the feature association, the initial pose estimation, a t moment left side The three dimensional space coordinate of each characteristic point and two dimensional image coordinate pass through minimum using light-stream adjustment in side image, image right Change the maximal possibility estimation that re-projection error obtains the pose of the mobile vehicle, obtains final pose.
The third aspect of the present invention, a kind of storage device, wherein being stored with a plurality of program, which is characterized in that described program It is above-mentioned based on disparity constraint and the two-way annular binocular vision speedometer examined to realize using being loaded by processor and being executed Calculation method.
The fourth aspect of the present invention, a kind of processing setting, including processor, storage device;Processor is adapted for carrying out each Program;Storage device is suitable for storing a plurality of program;It is characterized in that, described program is suitable for being loaded and being held by processor Row is to realize the above-mentioned binocular vision speedometer calculation method examined based on disparity constraint with two-way annular.
Beneficial effects of the present invention:
Present invention combination disparity constraint, can effectively purify characteristic point, avoid low-quality characteristic point with Track, to improve the quality and efficiency of signature tracking;The invention proposes adaptive two-way annulars to examine, and further eliminates outer Point improves the accuracy rate of feature association, and can be adaptively adjusted feature for the characteristic point variation in different motion The quality and quantity of point, to improve the positioning accuracy and real-time of binocular vision speedometer.
Detailed description of the invention
By reading a detailed description of non-restrictive embodiments in the light of the attached drawings below, the application's is other Feature, objects and advantages will become more apparent upon:
Fig. 1 is that the binocular vision speedometer examined based on disparity constraint and two-way annular of an embodiment of the present invention is calculated Method flow schematic diagram;
Fig. 2 is that the binocular vision speedometer examined based on disparity constraint and two-way annular of an embodiment of the present invention is calculated Method disparity constraint schematic diagram;
Fig. 3 is that the binocular vision speedometer examined based on disparity constraint and two-way annular of an embodiment of the present invention is calculated The adaptive two-way annular of method examines schematic diagram.
Specific embodiment
To make the object, technical solutions and advantages of the present invention clearer, below in conjunction with attached drawing to the embodiment of the present invention In technical solution be clearly and completely described, it is clear that described embodiments are some of the embodiments of the present invention, without It is whole embodiments.Based on the embodiments of the present invention, those of ordinary skill in the art are not before making creative work Every other embodiment obtained is put, shall fall within the protection scope of the present invention.
The application is described in further detail with reference to the accompanying drawings and examples.It is understood that this place is retouched The specific embodiment stated is only used for explaining related invention, rather than the restriction to the invention.It also should be noted that in order to just Part relevant to related invention is illustrated only in description, attached drawing.
It should be noted that in the absence of conflict, the features in the embodiments and the embodiments of the present application can phase Mutually combination.
The binocular vision speedometer calculation method examined based on disparity constraint and two-way annular of an embodiment of the present invention, Specifically includes the following steps:
Step S100 carries out left hand view according to the frequency acquisition of setting by the binocular camera being loaded on mobile vehicle The acquisition of picture, image right, obtains the corresponding left-side images of t-1, t moment, image right;
Step S200 carries out Shi-Tomasi Corner Detection to the setting image at t-1 moment obtained in step S100, mentions It is new to construct the setting image for the characteristic point of the setting image for taking newly-increased feature point set, and obtaining in conjunction with the t-1 moment Set of characteristic points;
Step S300, based on the new set of characteristic points of the setting image, using KLT optical flow method, by disparity constraint and Adaptive two-way annular is examined, and obtains the corresponding set of characteristic points of other images of t-1, t moment respectively, and carry out feature pass Connection;
Step S400, based in step S300 feature association as a result, obtaining the movement using PNP position and orientation estimation method The initial pose of carrier is estimated, and carries out three to characteristic point each in t moment left-side images, image right by binocular vision method Angling obtains the corresponding three dimensional space coordinate of each characteristic point;
Step S500, result, the initial pose estimation, t moment left-side images, the right side based on step S300 feature association The three dimensional space coordinate of each characteristic point and two dimensional image coordinate in the image of side, using light-stream adjustment, by minimizing re-projection Error obtains the maximal possibility estimation of the pose of the mobile vehicle, obtains final pose.In some preferred embodiments, Further include step S600 after step S500:
Based on the final pose at moment each before t moment, t moment is obtained by marginalisation method and Shu Er decomposition method Priori item rp, and by the priori item rpPrior uncertainty as maximal possibility estimation in step S500.
In order to more clearly to the present invention is based on the binocular vision speedometer calculating sides that disparity constraint and two-way annular are examined Method is illustrated, with reference to the accompanying drawing to a kind of embodiment of our inventive method based on disparity constraint and two-way annular inspection Each step carries out expansion detailed description in binocular vision speedometer calculation method.
The binocular vision speedometer calculation method examined based on disparity constraint and two-way annular of an embodiment of the present invention, Include the steps that S100-S600 described below.
Step S100 carries out left hand view according to the frequency acquisition of setting by the binocular camera being loaded on mobile vehicle The acquisition of picture, image right, obtains the corresponding left-side images of t-1, t moment, image right;
In the present embodiment, it before carrying out Image Acquisition, needs to demarcate the binocular camera assembled, calibration Parameter includes parameter between the camera intrinsic parameter of binocular camera and camera;
Left-side images collected, image right are corrected by OpenCV library function.
Step S200 carries out Shi-Tomasi Corner Detection to the setting image at t-1 moment obtained in step S100, mentions It is new to construct the setting image for the characteristic point of the setting image for taking newly-increased feature point set, and obtaining in conjunction with the t-1 moment Set of characteristic points;
In the present embodiment, the quantity for the preset total characteristic point that can be set is 200, certainly in some other implementation In example or other setting values, such as 100,150 etc..
The characteristic point for the setting image that the t-1 moment in this step obtains, acquisition methods are as follows:
At the t-1 moment, the binocular image at t-2, t-1 moment is obtained using the method tracking of step S200, step S300 The t-1 moment sets the characteristic point of image.
In this step, newly-increased feature point set, method are extracted are as follows:
The characteristic point of the setting image at t-1 moment is extracted by Shi-Tomasi angular-point detection method, and will be fallen into The feature point deletion of the primitive character point setting range neighborhood of the setting image, obtains newly-increased feature point.Set the original of image Beginning feature is the characteristic point of the setting image obtained at the t-1 moment.Primitive character point setting range neighborhood are as follows: be based on original spy Sign point obtains the corresponding border circular areas of each primitive character point according to the radius of setting respectively, and the intersection of all border circular areas is original Beginning characteristic point setting range neighborhood.
In the present embodiment, the image for carrying out Shi-Tomasi Corner Detection is the left-side images acquired at the t-1 moment, when It so, can also be the image right of t moment acquisition in some other embodiment.
Shi-Tomasi Corner Detection determines characteristic point, matching characteristic by comparing the minimal eigenvalue of gradient matrix When point, which introduce affine transformations, make characteristic point more accurate in frame matching, and exclude bad characteristic point.This step Feature extracting method is on the books in the more document in this field, herein not reinflated detailed description.
Step S300, based on the new set of characteristic points of the setting image, using KLT optical flow method, by disparity constraint and Adaptive two-way annular is examined, and obtains the corresponding set of characteristic points of other images of t-1, t moment respectively, and carry out feature pass Connection.
Further include the steps that feature point tracking number counts in the present embodiment: in t moment pose acquisition process, setting figure As characteristic point then tracks success, this feature point by disparity constraint and adaptive two-way annular inspection in new set of characteristic points Maximum tracking number add 1, to realize the statistics of tracking number.For newly-increased characteristic point, initially tracking number is 0.
Optical flow method is used for the principle of target detection: assigning a velocity vector to each of image pixel, in this way It is formed a motion vector field.In a certain particular moment, the point on image and the point on three-dimension object are corresponding one by one, in this way Corresponding relation can be calculated by projecting.
1, the initial time that Image Acquisition is carried out in binocular camera, only obtains a pair of of image, i.e. t=1, and t-1 is not present, At this point, screening the moment left-side imagesIn examined by left and right and the characteristic point of disparity constraint, and carry out left-side images, right side The matching of image characteristic point.
It is in the present embodiment the specific scheme is that ifCharacteristic point can by left and right examine and disparity constraint, then retain This feature point, and feature association is established, this feature point is otherwise deleted, method particularly includes:
Step 3001: willCharacteristic pointIt is tracked to obtain by KLT optical flow methodOn characteristic point
Step 3002, if characteristic pointWithY-coordinate difference be less than given threshold ρ1, then retain this feature point and go forward side by side Otherwise row following steps delete this feature point and skip following steps;
Step 3003, by characteristic pointTraceback obtainsOn characteristic point
Step 3004, ifWithDistance be less than given threshold δ1, then examined by left and right.
2, each moment of binocular camera at the second acquisition moment and later, the binocular figure at former and later two available moment Picture carries out feature association by following steps S301 to step S303 after the binocular image for obtaining t moment.
Step S301, by t-1 moment left-side imagesCharacteristic pointIt is tracked to obtain by KLT optical flow method T moment left-side imagesOn characteristic pointScreen t-1 moment left-side imagesIn by front and back examine characteristic point and build It is verticalWithFeature association.
In the implementation case this step the specific scheme is that ifCharacteristic point can be examined by front and back, then protect This feature point is stayed, and establishes feature association, otherwise deletes this feature point, method particularly includes:
Step 3011, willCharacteristic pointIt is tracked to obtain by KLT optical flow methodOn characteristic point
Step 3012, by characteristic pointTraceback obtainsOn characteristic point
Step 3013, ifWithDistance be less than given threshold δ2, then examined by front and back.
Step S302, by t moment left-side imagesCharacteristic pointIt is tracked to obtain in t moment by KLT optical flow method Image rightOn characteristic pointScreen t moment left-side imagesThe characteristic point with disparity constraint is examined by left and right, and is built It is verticalWithFeature association.
In the present embodiment this step the specific scheme is that ifCharacteristic point can by left and right examine and parallax about Beam then retains this feature point, and establishes feature association, otherwise deletes this feature point, method particularly includes:
Step 3021: willCharacteristic pointIt is tracked to obtain by KLT optical flow methodOn characteristic point
Step 3022: if characteristic pointWithY-coordinate difference be less than given threshold ρ1, then retain this feature point and go forward side by side Otherwise row following steps delete this feature point and skip following steps;
Step 3023, by characteristic pointTraceback obtainsOn characteristic point
Step 3024, ifWithDistance be less than given threshold δ3, then examined by left and right.
It is illustrated in figure 2 the parallax for the binocular vision speedometer calculation method examined based on disparity constraint and two-way annular about Beam schematic diagram, show in figure byCharacteristic pointIt is tracked to obtain by KLT optical flow methodOn Characteristic pointDotted line is the allowed band [+ρ for showing y-coordinate in figure1,-ρ1],Middle characteristic pointRight side solid line indicates characteristic pointWith characteristic pointY-coordinate is equal.
Step S303, by t moment right part of flgOn characteristic pointIt is tracked to obtain in t-1 by KLT optical flow method Carve image rightOn characteristic pointScreen t moment image rightPass through the adaptive rear preceding characteristic point examined.
In the present embodiment this step the specific scheme is that ifCharacteristic point can be by examining before after adaptive, then Retain this feature point, otherwise delete this feature point, method particularly includes:
Step 3031, willCharacteristic pointIt is tracked to obtain by KLT optical flow methodOn characteristic point
Step 3032, by characteristic pointTraceback obtainsOn characteristic point
Step 3033, ifWithDistance be less than adaptive threshold δ4, then pass through adaptive rear preceding inspection;
Adaptive threshold δ4Equation such as formula (1) shown in:
Wherein, ρ and ε is parameter preset (value is ρ=0.23, ε=5 in the present embodiment), and loss is t moment left-side images With the characteristic point number lost, (i.e. preset total characteristic point number subtracts t when the characteristic point of feature point tracking t-1 moment left-side images Moment left-side images characteristic point successfully tracks the number of the characteristic point of t-1 moment left-side images, preset total spy in the present embodiment Sign point number is that 200), maxtrack is the maximum tracking number of current signature point.In the present embodiment, each moment carries out position When appearance calculates, two-way annular is examined since the left-side images of last moment.In some other embodiment, if two-way annular It examines since the image right at t-1 moment, then loss is t moment image right feature point tracking t-1 moment right part of flg at this time With the characteristic point number lost when the characteristic point of picture, in this case, two-way annular is examined since the image right of last moment.
It is illustrated in figure 3 adaptively double based on disparity constraint and the binocular vision speedometer calculation method of two-way annular inspection Schematic diagram is examined to annular, is shown in figureTwo-way annular is carried out by KLT optical flow method to examine, In, the solid arrow between every two image indicates that tracking is carried out by KLT optical flow method obtains characteristic point in arrow meaning image Process, dotted arrow indicate traceback obtain the process of arrow meaning image characteristic point.In figureWithBetween Solid arrow and dotted arrow are respectively the t-1 momentWithBetween by tracking and antitracking obtain individual features point Process.
Step S400 is based on the feature association, the initial bit of the mobile vehicle is obtained using PNP position and orientation estimation method Appearance estimation, and obtain carrying out trigonometric ratio to each characteristic point by binocular vision method, obtain the corresponding three-dimensional space of each characteristic point Coordinate;
According to the two dimensional character of present frame point and corresponding three dimensional space coordinate, initial pose is obtained using PNP method and is estimated Meter.The characteristic point that present frame is newly extracted carries out trigonometric ratio by the method for binocular vision, obtains corresponding three dimensional space coordinate, It is resolved for subsequent pose.
Step S500, based on each in the feature association, the initial pose estimation, t moment left-side images, image right The three dimensional space coordinate and two dimensional image coordinate of characteristic point obtain institute by minimizing re-projection error using light-stream adjustment The maximal possibility estimation for stating the pose of mobile vehicle obtains final pose.
The pose that the embodiment of the present invention directly acquires is the pose of binocular camera left camera, passes through left camera and movement The pose mapping relations of carrier, the pose of available mobile vehicle.In some other embodiment, if it is two-way annular examine from The image right at t-1 moment starts, then is the pose of binocular camera right camera by the pose that the above method directly acquires, together Sample passes through the pose mapping relations of right camera and mobile vehicle, the pose of available mobile vehicle.
According to feature association as a result, constructing re-projection error for each characteristic point on each picture frame.The re-projection Error is by the picture frame after projecting to this feature point from the position of first time observation.Assuming that first observes spy The picture frame for levying point l is i, then its re-projection error such as formula (2) on picture frame t is shown:
Wherein,It is equivalent toIndicate observation point of the characteristic point l on picture frame t;It is characteristic point l in image The observation model of frame t, χ indicate pose;πcIt is pin-hole model, feature is projected into image coordinate system from camera coordinates system;T is phase The homogeneous matrix of seat in the plane appearance, TiIndicate the correspondence pose of picture frame i, TtIndicate the correspondence pose of picture frame t.λlIndicate characteristic point l Depth.
For binocular vision speedometer, this method constructs space re-projection error and time re-projection using this method simultaneously Error.
It is estimated as initial value with initial pose, is estimated using the maximum likelihood that light-stream adjustment obtains the pose in sliding window Meter can solve the equation using gauss-newton method as shown in formula (3).
Wherein, S is image measurement value set (i.e. the two dimensional image coordinate set of characteristic point),It is covariance matrix, χ* It is optimal pose (the final pose resolved), χ is pose to be optimized, and n is moment serial number,It is characteristic point two dimensional image Coordinate,For pin-hole model πc, rpFor priori item obtained in step S600.
Priori item r is increased in maximal possibility estimation in the present embodimentp, public certainly in some other embodiments Formula (3) can also remove priori item rp
In order to improve the present invention is based on disparity constraint and it is two-way annular examine binocular vision speedometer calculation method when Effect property increases step S600 in some embodiments.
Step S600 is obtained based on the final pose at moment each before t moment by marginalisation method and Shu Er decomposition method Take the priori item r of t momentp, and by the priori item rpPrior uncertainty as maximal possibility estimation in step S500.
By the step as system mode is continuously increased, system mode (final pose) number is reduced using marginalisation method Amount guarantees that binocular vision speedometer being capable of real time execution to have the function that reduce computation complexity.
It is priori item r that marginalisation method, which is decomposed by Shu Er by part system condition conversion before,p, and by it from sliding It is removed in window, provides prior information for the state of sliding window.
The pose and new picture frame pose that still retain after marginalisation constitute the pose in sliding window, and circulation uses light beam The maximal possibility estimation of adjustment method acquisition pose.
It can be with specific reference to " Leutenegger S, Lynen S, Bosse M, et al.Keyframe- in this step based visual-inertial odometry using nonlinear optimization[J].The International Journal of Robotics Research, 2015,34 (3): 314-334. ", it is not reinflated herein It is described in detail.
In the description of above-mentioned technical proposal, step S600 is intended merely to clearly after being placed on step S500 to technology Scheme is described, rather than the restriction to sequence of steps, can be placed in front of step S500 in some embodiments.
The a kind of of second embodiment of the invention is calculated based on disparity constraint with the binocular vision speedometer of two-way annular inspection System, the system include binocular image acquiring unit, initial characteristics point extraction unit, feature point extraction and feature association unit, Initial pose estimation unit, maximal possibility estimation unit;
The binocular image acquiring unit, is configured to the binocular camera by being loaded on mobile vehicle, according to setting Frequency acquisition carries out the acquisition of left-side images, image right, obtains t, t+1 moment corresponding left-side images, image right;
The initial characteristics point extraction unit, was configured to the t-1 moment obtained in the binocular image acquiring unit It sets image and carries out Shi-Tomasi Corner Detection, the setting extracting newly-increased feature point set, and obtaining in conjunction with the t-1 moment The characteristic point of image constructs the new set of characteristic points of the setting image;
The feature point extraction and feature association unit are configured to make the set of characteristic points new based on the setting image, Using KLT optical flow method, is examined by disparity constraint and adaptive two-way annular, obtain other images pair at t, t+1 moment respectively The set of characteristic points answered, and carry out feature association;
The initial pose estimation unit is configured to the feature association as a result, obtaining using PNP position and orientation estimation method The initial pose estimation of the mobile vehicle is obtained, and by binocular vision method to each spy in t moment left-side images, image right Sign point carries out trigonometric ratio, obtains the corresponding three dimensional space coordinate of each characteristic point;
The maximal possibility estimation unit is configured to the feature association, the initial pose estimation, a t moment left side The three dimensional space coordinate of each characteristic point and two dimensional image coordinate in side image and image right, using light-stream adjustment, by most Smallization re-projection error obtains the maximal possibility estimation of the pose of the mobile vehicle, obtains final pose.
Person of ordinary skill in the field can be understood that, for convenience and simplicity of description, foregoing description The specific work process and related explanation of storage device, processing unit, can refer to corresponding processes in the foregoing method embodiment, Details are not described herein.
It should be noted that the binocular vision mileage provided by the above embodiment examined based on disparity constraint with two-way annular Count computing system, only the example of the division of the above functional modules, in practical applications, can according to need and incite somebody to action Above-mentioned function distribution is completed by different functional modules, i.e., by the embodiment of the present invention module or step decompose again or Combination, for example, the module of above-described embodiment can be merged into a module, can also be further split into multiple submodule, with Complete all or part of function described above.For module involved in the embodiment of the present invention, the title of step, only In order to distinguish modules or step, it is not intended as inappropriate limitation of the present invention.
Third of the present invention applies a kind of storage device of example, wherein being stored with a plurality of program, described program is suitable for by processor It loads and executes to realize the above-mentioned binocular vision speedometer calculation method examined based on disparity constraint with two-way annular.
The present invention the 4th applies a kind of processing unit of example, including processor, storage device;Processor is adapted for carrying out each item Program;Storage device is suitable for storing a plurality of program;Described program be suitable for loaded by processor and executed with realize it is above-mentioned based on The binocular vision speedometer calculation method that disparity constraint and two-way annular are examined.
Person of ordinary skill in the field can be understood that, for convenience and simplicity of description, foregoing description The specific work process and related explanation of storage device, processing unit, can refer to corresponding processes in the foregoing method embodiment, Details are not described herein.
Those skilled in the art should be able to recognize that, mould described in conjunction with the examples disclosed in the embodiments of the present disclosure Block, method and step, can be realized with electronic hardware, computer software, or a combination of the two, software module, method and step pair The program answered can be placed in random access memory (RAM), memory, read-only memory (ROM), electrically programmable ROM, electric erasable and can compile Any other form of storage well known in journey ROM, register, hard disk, moveable magnetic disc, CD-ROM or technical field is situated between In matter.In order to clearly demonstrate the interchangeability of electronic hardware and software, in the above description according to function generally Describe each exemplary composition and step.These functions are executed actually with electronic hardware or software mode, depend on technology The specific application and design constraint of scheme.Those skilled in the art can carry out using distinct methods each specific application Realize described function, but such implementation should not be considered as beyond the scope of the present invention.
Term " first ", " second " etc. are to be used to distinguish similar objects, rather than be used to describe or indicate specific suitable Sequence or precedence.
Term " includes " or any other like term are intended to cover non-exclusive inclusion, so that including a system Process, method, article or equipment/device of column element not only includes those elements, but also including being not explicitly listed Other elements, or further include the intrinsic element of these process, method, article or equipment/devices.
So far, it has been combined preferred embodiment shown in the drawings and describes technical solution of the present invention, still, this field Technical staff is it is easily understood that protection scope of the present invention is expressly not limited to these specific embodiments.Without departing from this Under the premise of the principle of invention, those skilled in the art can make equivalent change or replacement to the relevant technologies feature, these Technical solution after change or replacement will fall within the scope of protection of the present invention.

Claims (16)

1. a kind of binocular vision speedometer calculation method examined based on disparity constraint with two-way annular, which is characterized in that pose Calculation method the following steps are included:
Step S100 carries out left-side images, the right side according to the frequency acquisition of setting by the binocular camera being loaded on mobile vehicle The acquisition of side image obtains the corresponding left-side images of t-1, t moment, image right;
Step S200 carries out Shi-Tomasi Corner Detection to the setting image at t-1 moment obtained in step S100, extracts new The characteristic point for the setting image for increasing set of characteristic points, and obtaining in conjunction with the t-1 moment constructs the new feature of the setting image Point set;
Step S300, based on the new set of characteristic points of the setting image, using KLT optical flow method, by disparity constraint and adaptive It answers two-way annular to examine, obtains the corresponding set of characteristic points of other images of t-1, t moment respectively, and carry out feature association;
Step S400, based in step S300 feature association as a result, obtaining the mobile vehicle using PNP position and orientation estimation method Initial pose estimation, and by binocular vision method to characteristic point each in t moment left-side images and image right carry out triangle Change, obtains the corresponding three dimensional space coordinate of each characteristic point;
Step S500, result, the initial pose estimation, t moment left-side images, right part of flg based on step S300 feature association The three dimensional space coordinate and two dimensional image coordinate of each characteristic point as in, using light-stream adjustment, by minimizing re-projection error The maximal possibility estimation of the pose of the mobile vehicle is obtained, final pose is obtained.
2. the binocular vision speedometer calculation method according to claim 1 examined based on disparity constraint with two-way annular, It is characterized in that, left-side images collected, image right are corrected by OpenCV library function in step S100.
3. the binocular vision speedometer calculation method according to claim 1 examined based on disparity constraint with two-way annular, It is characterized in that, " characteristic point for the setting image that the t-1 moment obtains ", acquisition methods in step S200 are as follows:
At the t-1 moment, the binocular image at t-2, t-1 moment, the t-1 obtained using the method tracking of step S200, step S300 The characteristic point of moment setting image.
4. the binocular vision speedometer calculation method according to claim 2 examined based on disparity constraint with two-way annular, It is characterized in that, " newly-increased feature point set is extracted " in step S200, method are as follows:
The characteristic point of the setting image at t-1 moment is extracted by Shi-Tomasi angular-point detection method, and will be fallen into described The feature point deletion for setting the primitive character point setting range neighborhood of image, obtains newly-increased feature point;The original of the setting image Beginning feature is the characteristic point of the setting image obtained at the t-1 moment.
5. according to claim 1-4 based on the binocular vision speedometer that disparity constraint is examined with two-way annular Calculation method, which is characterized in that the left-side images for setting image and being acquired as t moment.
6. the binocular vision speedometer calculation method according to claim 5 examined based on disparity constraint with two-way annular, It is characterized in that, step S300 " obtains the corresponding set of characteristic points of other images of t-1, t moment respectively, and carries out feature pass Connection ", method are as follows:
Step S301, by t-1 left-side images left imageCharacteristic pointIt is tracked to obtain in t by KLT optical flow method Moment left imageCharacteristic pointThe characteristic point that screening t-1 moment left-side images are examined by front and back, and establishWithFeature association;
Step S302, by t moment left-side imagesCharacteristic pointIt is tracked to obtain on the right side of t moment by KLT optical flow method ImageOn characteristic pointThe characteristic point with disparity constraint is examined by left and right, and is establishedWithFeature association;
T moment image right is by step S303On characteristic pointIt is tracked to obtain in t-1 by KLT optical flow method Carve image rightOn characteristic pointScreen t moment image rightPass through the adaptive rear preceding characteristic point examined.
7. the binocular vision speedometer calculation method examined according to claim 5 based on disparity constraint and two-way annular, It is characterized in that, " the corresponding set of characteristic points of other images of t-1, t moment is obtained respectively " in step S300, if t is initial It carves, it willCharacteristic pointIt is tracked to obtain by KLT optical flow methodOn characteristic pointScreening, which obtains, passes through left and right Examine the characteristic point with disparity constraint.
8. the binocular vision speedometer calculation method examined according to claim 7 based on disparity constraint and two-way annular, It is characterized in that, " screening obtains the characteristic point by left and right inspection and disparity constraint ", method are as follows:
It obtainsWithY-coordinate difference be less than given threshold ρ1Characteristic point, and by characteristic pointTraceback obtains On characteristic pointIfWithDistance be less than given threshold δ1, then examined by left and right.
9. the binocular vision speedometer calculation method examined according to claim 6 based on disparity constraint and two-way annular, It is characterized in that, " screening t-1 moment left-side images in step S301In by front and back examine characteristic point ", method Are as follows:
By characteristic pointTraceback obtainsOn characteristic point
IfWithDistance be less than given threshold δ2, then as the characteristic point examined by front and back.
10. the binocular vision speedometer calculation method according to claim 6 examined based on disparity constraint with two-way annular, It is characterized in that, " screening t moment left-side images in step S302The characteristic point with disparity constraint is examined by left and right ", side Method are as follows:
Step S3021, if characteristic pointWithY-coordinate difference be less than given threshold ρ1, then retain this feature point and execute Otherwise step S3022 deletes this feature point;
Step S3022, by characteristic pointTraceback obtainsOn characteristic point
Step S3023, ifWithDistance be less than given threshold δ3, then as the characteristic point by left and right detection.
11. the binocular vision speedometer calculation method according to claim 6 examined based on disparity constraint with two-way annular, It is characterized in that, " screening t moment image right in step S303Pass through the adaptive rear preceding characteristic point examined ", method Are as follows:
By characteristic pointTraceback obtainsOn characteristic point
IfWithDistance be less than adaptive threshold δ4, then as the characteristic point by adaptive rear preceding inspection;
Wherein, adaptive threshold δ4Calculation method are as follows:
Wherein, ρ and ε is parameter preset, and loss is the characteristic point of t-1 moment image right feature point tracking t moment left-side images When with the characteristic point number lost, maxtrack is the maximum tracking number of current signature point.
12. the binocular vision speedometer according to claim 1-4 examined based on disparity constraint with two-way annular Calculation method, which is characterized in that in step S500 " maximal possibility estimation of pose is obtained by minimizing re-projection error ", Method are as follows:
Step S501, according to feature association as a result, on each picture frame each characteristic point building space re-projection error and Time re-projection error;
Step S502 obtains the maximal possibility estimation of pose in sliding window using light-stream adjustment.
13. the binocular vision speedometer according to claim 1-4 examined based on disparity constraint with two-way annular Calculation method, which is characterized in that further include step S600 after step S500:
Based on the final pose at moment each before t moment, the priori of t moment is obtained by marginalisation method and Shu Er decomposition method Item rp, and by the priori item rpPrior uncertainty as maximal possibility estimation in step S500.
14. a kind of binocular vision speedometer computing system examined based on disparity constraint with two-way annular, which is characterized in that this is System includes that binocular image acquiring unit, initial characteristics point extraction unit, feature point extraction and feature association unit, initial pose are estimated Count unit, maximal possibility estimation unit;
The binocular image acquiring unit, is configured to the binocular camera by being loaded on mobile vehicle, according to the acquisition of setting Frequency carries out the acquisition of left-side images, image right, obtains t, t+1 moment corresponding left-side images, image right;
The initial characteristics point extraction unit, is configured to one to the t-1 moment obtained in the binocular image acquiring unit Image carries out Shi-Tomasi Corner Detection, the setting image for extracting newly-increased feature point set, and obtaining in conjunction with the t-1 moment Characteristic point, construct the new set of characteristic points of the setting image;
The feature point extraction and feature association unit are configured to make the set of characteristic points new based on the setting image, use KLT optical flow method is examined by disparity constraint and adaptive two-way annular, other images for obtaining t, t+1 moment respectively are corresponding Set of characteristic points, and carry out feature association;
The initial pose estimation unit is configured to the feature association as a result, obtaining institute using PNP position and orientation estimation method The initial pose estimation of mobile vehicle is stated, and by binocular vision method to each characteristic point in t moment left-side images, image right Trigonometric ratio is carried out, the corresponding three dimensional space coordinate of each characteristic point is obtained;
The maximal possibility estimation unit is configured to the feature association, the initial pose estimation, t moment left hand view The three dimensional space coordinate of each characteristic point and two dimensional image coordinate pass through minimum using light-stream adjustment in picture and image right Re-projection error obtains the maximal possibility estimation of the pose of the mobile vehicle.
15. a kind of storage device, wherein being stored with a plurality of program, which is characterized in that described program is applied by processor load simultaneously It executes to realize the described in any item binocular vision speedometers examined based on disparity constraint with two-way annular of claim 1-13 Calculation method.
16. a kind of processing setting, including processor, storage device;Processor is adapted for carrying out each program;Storage device is fitted For storing a plurality of program;It is characterized in that, described program is suitable for being loaded by processor and being executed to realize claim 1- 13 described in any item binocular vision speedometer calculation methods examined based on disparity constraint with two-way annular.
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