CN115682937A - Calibration method of automatic three-dimensional laser scanner - Google Patents
Calibration method of automatic three-dimensional laser scanner Download PDFInfo
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Abstract
A calibration method of an automatic three-dimensional laser scanner belongs to the technical field of calibration methods. The problem of among the prior art automatic three-dimensional scanner install usually in fixed environment, the space and the operation of calibration all receive the restriction, be not convenient for the calibration is solved. The calibration method of the invention presets a plurality of target poses; then, an operator enables a perspective projection quadrangle representing the current pose of the calibration plate in a computer screen to coincide with a perspective projection quadrangle representing the target pose of the calibration plate by changing the pose of the calibration plate in the hand, and an image of the calibration plate acquired under the current pose and an image of a laser line projected on the calibration plate are saved; and repeating the execution until all target poses are traversed, and realizing the calibration of the visual laser detector by using all the saved images. Under the condition that the calibration space and operation are limited, the scanner does not need to be taken down from the installation station, and the rapid calibration of the visual laser detector and the motion trail is realized by using the same calibration plate.
Description
Technical Field
The invention belongs to the technical field of calibration methods, and particularly relates to a calibration method of an automatic three-dimensional laser scanner.
Background
For a long time, the accurate measurement of the geometric dimension of a real object mainly depends on a contact type manual measurement mode of measuring tools such as a vernier caliper, a micrometer and an angle gauge, the measurement mode cannot measure the surface of the object with an irregular shape, and technical bottlenecks also exist for measuring objects such as cultural relics and ancient sites which require non-contact. With the development of related subjects and the drive of new requirements of new technologies, a three-dimensional scanning technology comes along, the technology can calculate the spatial distribution of point clouds according to the collected object surface information under the condition of not contacting with a measured object, and integrates point cloud data into a triangular mesh model of the measured object in a computer through a series of curved surface reconstruction methods.
With the advance of industrial automation and intellectualization, the demand of automatic three-dimensional detection is more and more, the size and shape of the object to be detected are various, and the demand is that the automatic three-dimensional detection equipment can adapt to the detection demand of different objects as much as possible, at present, the three-dimensional scanning equipment applied to the measurement field mainly comprises a photographing three-dimensional scanner based on raster projection and a handheld three-dimensional scanner based on multi-line laser, wherein the photographing three-dimensional scanner uses a projector to continuously project a plurality of light and shade stripes with optical coding characteristics to the surface of the object to be detected, uses a binocular camera to synchronously acquire the reflected light of each light and shade stripe on the surface of the object, and performs unified optical decoding on all acquired images to obtain three-dimensional point cloud data, and the equipment requires that the position of the scanner and the object to be detected is relatively fixed during scanning, and can only scan the object with the size of a fixed area each time, and can only customize the three-dimensional scanner again when the size of the object to be detected exceeds the measurement range; the hand-held three-dimensional scanner adopting the laser as the light source needs to paste mark points on the surface of a measured object, in the scanning step, an operator holds the scanner to traverse the surface of the measured object to obtain complete point cloud data, and because the mark points need to be pasted before scanning and the scanning step needs manual participation, the device is only suitable for scanning large objects or sampling detection, and cannot realize automation.
The automatic three-dimensional laser scanner with the visual laser detector combined with the guide rail can meet the requirement of the automatic detection industry on the compatibility of detection equipment, and only the movement stroke of the guide rail needs to be changed for detected objects with different sizes. The detection precision is the most important index of the three-dimensional scanner, and the calibration precision of the three-dimensional scanner directly determines the detection precision, but the automatic three-dimensional scanner is usually installed in a fixed environment, so that the calibration space and operation are greatly limited, and the calibration is inconvenient.
Disclosure of Invention
The invention aims to provide an automatic calibration method of a three-dimensional laser scanner, which realizes the calibration of the three-dimensional laser scanner by using the same calibration plate without taking the three-dimensional laser scanner off an installation station under the condition of limited calibration space and operation, comprises the rapid calibration of a visual laser detector and a motion track, realizes the multifunctional multiplexing of the same calibration plate, and reduces the complexity of the calibration method.
The invention adopts the following technical scheme to achieve the purpose.
The invention discloses a calibration method of an automatic three-dimensional laser scanner, which comprises the following steps:
presetting a plurality of target poses of a calibration plate in a visual laser detector coordinate system;
selecting a target pose, enabling the visual laser detector to be in a static state, enabling an operator to hold the calibration plate to move towards the target pose, displaying a perspective projection quadrangle of the calibration plate at the current pose on a computer screen in real time, enabling the operator to use the two perspective projection quadrangles on the computer screen as prompt information when the calibration plate reaches the perspective projection quadrangle of the target pose, enabling the perspective projection quadrangle representing the current pose of the calibration plate in the computer screen to be overlapped with the perspective projection quadrangle representing the target pose of the calibration plate by changing the pose of the calibration plate in the hand, and storing an image of the calibration plate acquired by the visual laser detector at the current pose and an image of a laser line emitted by the visual laser detector projected on the calibration plate by the computer after the perspective projection quadrangles;
step three, repeatedly executing the step two until all target poses preset in the step one are traversed, and calibrating the visual laser detector by using all stored images;
the coordinate system of the visual laser detector takes a center connecting line of binocular cameras of the visual laser detector as a Y axis, a midpoint of the center connecting line of the binocular cameras of the visual laser detector as an origin, the Y axis and an incident light axis of the binocular cameras form a YOZ coordinate plane, a Z axis is in the same direction as incident light of the binocular cameras, an X axis is perpendicular to the YOZ coordinate plane, and the directions of the X axis, the Y axis and the Z axis accord with right hand rules;
the calibration plate is a flat plate with a plurality of characteristic points attached to the surface, the characteristic points are points which can be recognized by the visual laser detector, and the coordinates of all the characteristic points on the calibration plate in a calibration plate coordinate system are known.
Further, the method for acquiring the perspective projection quadrangle of the calibration plate in the current pose comprises the following steps:
1) Identifying and extracting feature points on a calibration plate
A binocular camera of the visual laser detector synchronously acquires images on the current pose calibration plate and transmits the images to a computer, the computer respectively identifies all characteristic points in the left viewpoint image and the right viewpoint image, and the coordinate of each characteristic point in a coordinate system of the visual laser detector is calculated according to polar constraint and triangulation principles;
2) Calculating a rotation matrix and a translation matrix between a coordinate system of a current pose calibration plate and a coordinate system of a visual laser detector
Calculating a rotation matrix and a translation matrix between the coordinate system of the current pose calibration plate and the coordinate system of the visual laser detector by using the coordinates of the same group of characteristic points in the coordinate system of the visual laser detector and the coordinates in the coordinate system of the current pose calibration plate by using a least square method;
3) Computing perspective projection points of four corners of a calibration plate
The method comprises the steps of calculating coordinates of four corners of a current pose calibration plate in a visual laser detector coordinate system by utilizing a rotation matrix and a translation matrix between the current pose calibration plate coordinate system and the visual laser detector coordinate system, establishing a perspective projection model in the visual laser detector coordinate system, wherein a projection plane is an XOY plane, a projection center and the calibration plate are positioned on two sides of the projection plane, projecting the coordinates of the four corners of the current pose calibration plate in the visual laser detector coordinate system onto the projection plane according to the established perspective projection model to obtain two-dimensional coordinate values of four projection points, and sequentially connecting the four projection points to obtain a perspective projection quadrangle of the calibration plate in the current pose.
Further, in the step 3), the distance from the projection center to the projection plane is set as the focal length of the lens of the binocular camera.
Further, the method for acquiring the perspective projection quadrangle of the calibration plate in the target pose comprises the following steps:
1) Calculating a rotation matrix and a translation matrix between a coordinate system of a target pose calibration plate and a coordinate system of a visual laser detector
Calculating a rotation matrix and a translation matrix between a target pose calibration plate coordinate system and a visual laser detector coordinate system by using the coordinates of the same group of characteristic points in the visual laser detector coordinate system and the coordinates in the target pose calibration plate coordinate system by using a least square method;
2) Computing perspective projection points of four corners of a calibration plate
The method comprises the steps of calculating coordinates of four corners of a target pose calibration plate in a visual laser detector coordinate system by utilizing a rotation matrix and a translation matrix between the target pose calibration plate coordinate system and the visual laser detector coordinate system, establishing a perspective projection model in the visual laser detector coordinate system, wherein a projection plane is an XOY plane, a projection center and the calibration plate are positioned on two sides of the projection plane, projecting the coordinates of the four corners of the target pose calibration plate in the visual laser detector coordinate system onto the projection plane according to the established perspective projection model to obtain two-dimensional coordinate values of four projection points, and sequentially connecting the four projection points to obtain a perspective projection quadrangle of the calibration plate in the target pose.
Further, in the step 2), the distance from the projection center to the projection plane is set as the focal length of the lens of the binocular camera.
Further, in the second step, the computer displays the target poses according to a preset sequence, and after the image of the previous target pose is stored, the computer screen automatically displays the perspective projection quadrangle of the next target pose.
Further, in the third step, the calibration of the visual laser detector is implemented by using all the stored images, and the method includes the following steps:
1) Extracting position coordinates of feature points in all stored images in the images, obtaining an equivalent focal length of a binocular camera lens, projection point coordinates of an optical axis of the binocular camera lens on the images and a distortion coefficient of the binocular camera lens by using a Zhang Zhengyou calibration method and coordinates of the feature points in a calibration plate coordinate system, and obtaining a rotation matrix and a translation matrix between the binocular cameras by using the binocular calibration method;
2) And extracting the position coordinates of the laser lines in all the stored images, and obtaining a plane equation of the laser lines by adopting a binocular calibration method.
The invention discloses a calibration method of an automatic three-dimensional laser scanner, which comprises the following steps:
adjusting a guide rail to a movement zero position, aligning a calibration plate to a visual laser detector, identifying and extracting characteristic points on the calibration plate by the visual laser detector, and calculating a rotation matrix and a translation matrix between a coordinate system of the calibration plate and a coordinate system of the visual laser detector by using the characteristic points;
keeping the calibration plate in an original static state, starting a guide rail, driving the visual laser detector to move along a linear direction by the guide rail, and continuously calculating the coordinate of the origin of the coordinate system of the visual laser detector in the coordinate system of the calibration plate at each moment in the movement process of the visual laser detector to obtain a group of three-dimensional coordinate data;
performing linear fitting on the three-dimensional coordinate data to obtain a linear direction vector, and transforming the direction vector from the calibration plate coordinate system to the visual laser detector coordinate system when the guide rail is located at the movement zero position by using a rotation matrix and a translation matrix between the calibration plate coordinate system and the visual laser detector coordinate system when the guide rail is located at the movement zero position, which are obtained by calculation, so as to obtain a movement track of the visual laser detector;
the coordinate system of the visual laser detector takes a center connecting line of binocular cameras of the visual laser detector as a Y axis, a midpoint of the center connecting line of the binocular cameras of the visual laser detector as an origin, the Y axis and an incident light axis of the binocular cameras form a YOZ coordinate plane, a Z axis is in the same direction as incident light of the binocular cameras, an X axis is perpendicular to the YOZ coordinate plane, and the directions of the X axis, the Y axis and the Z axis accord with right hand rules;
the calibration plate is a flat plate with a plurality of characteristic points attached to the surface, the characteristic points are points which can be identified by the visual laser detector, and the coordinates of all the characteristic points on the calibration plate in the coordinate system of the calibration plate are known.
Furthermore, the automatic three-dimensional laser scanner comprises a visual laser detector, a guide rail, a supporting structure, a controller and a computer; visual laser detector comprises binocular camera and the laser instrument that can launch a laser line or many parallel laser lines, visual laser detector installs on the guide rail, the guide rail is installed on bearing structure, the guide rail is connected with the detector, the computer all links to each other with controller, visual laser detector, and the computer is through the start-up, stop and the reset of control controller control guide rail, and visual laser detector is linear motion along the guide rail, and visual laser detector gathers the image and transmits to the computer in, the computer is to the image display of gathering, save and handle.
Compared with the prior art, the invention has the beneficial effects that:
according to the calibration method of the automatic three-dimensional laser scanner, an operator can finish the calibration of the visual laser detector by holding the calibration plate by hand, and the calibration of the running track can be finished by simply fixing the same calibration plate. Compared with a calibration method adopting a fixing device, the calibration method does not need a support structure of a calibration plate, can set the target pose according to the actual situation, and is particularly suitable for the working environment with limited calibration space; compared with a calibration method of a handheld scanner, the handheld scanner can also realize that an operator can carry out calibration by holding a calibration plate by the hand, but the handheld scanner takes a calibration plate coordinate system as a world coordinate system, a pose prompt in a computer is a mirror image of the motion direction of the operator, and the operator can hardly reach a target pose according to prompt information.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.
FIG. 1 is a schematic view of an automated three-dimensional laser scanner and calibration plate according to the present invention;
FIG. 2 is a schematic view of a vision laser detector of the automated three-dimensional laser scanner of the present invention;
FIG. 3 is a perspective projection quadrilateral of a calibration plate on a computer screen at a current pose and a perspective projection quadrilateral of a target pose in the calibration method of the automated three-dimensional laser scanner of the present invention;
fig. 4 is a schematic structural view of a calibration plate (to which circular feature points are attached) in the calibration method of the automated three-dimensional laser scanner according to the present invention;
FIG. 5 is a calibration plate image acquired by a binocular camera of a visual laser detector in the calibration method of the automated three-dimensional laser scanner according to the present invention;
FIG. 6 is a calibration plate image containing laser lines acquired by a binocular camera of a vision laser detector in the calibration method of the automatic three-dimensional laser scanner according to the present invention;
in the figure: 1. the device comprises a visual laser detector 1-1, a binocular camera 1-2, a laser 2, a guide rail 3, a support structure 4, a controller 5, a computer 6, a calibration plate 7, a laser line 8 and a perspective projection quadrangle of the calibration plate at the current pose, and a perspective projection quadrangle of the calibration plate at the target pose 9.
Detailed Description
For a further understanding of the invention, reference will now be made to the preferred embodiments of the invention, but it is to be understood that the description is intended to illustrate further features and advantages of the invention, and not to limit the scope of the claims.
The calibration method of the automated three-dimensional laser scanner according to the present invention is not particularly limited with respect to the structure of the automated three-dimensional laser scanner, and the automated three-dimensional laser scanner including the components used in the calibration method according to the present invention is applicable to the calibration method according to the present invention. In the present embodiment, an automated three-dimensional laser scanner is adopted as the prior art, and the structure is shown in fig. 1 and fig. 2, and mainly comprises a visual laser detector 1, a guide rail 2, a support structure 3, a controller 4 and a computer 5; wherein vision laser detector 1 comprises binocular camera 1-1 and laser instrument 1-2 that can launch a laser line or many parallel laser lines, and vision laser detector 1 installs on guide rail 2, and guide rail 2 installs on bearing structure 3, and guide rail 2 is connected with controller 4, and computer 5 all links to each other with controller 4, vision laser detector 1, and computer 5 is through the start-up, stop and the reset of control controller 4 control guide rail 2, and vision laser detector 1 is along being linear motion at guide rail 2, and vision laser detector 1 gathers the image and transmits to computer 5 in, and computer 5 is to the image display of gathering, save and handle.
The calibration method of the automatic three-dimensional laser scanner is suitable for calibrating the visual laser detector 1 and calibrating the motion trail of the laser detector 1.
As shown in fig. 3, 5 and 6, the calibration method of the automated three-dimensional laser scanner of the present invention for the calibration of the vision laser detector 1 includes the following steps:
presetting a plurality of target poses of a calibration plate 6 in a coordinate system of a visual laser detector 1 (the target poses are uniformly distributed in a measurement area of the visual laser detector);
during calibration, selecting a target pose, enabling the visual laser detector 1 to be in a static state, enabling an operator to hold the calibration plate 6 to move towards the target pose, displaying a perspective projection quadrangle 8 of the calibration plate 6 at the current pose on a screen of the computer 5 in real time, enabling the operator to use two perspective projection quadrangles on the screen of the computer 5 as prompt information when the calibration plate 6 reaches a perspective projection quadrangle 9 of the target pose, enabling the perspective projection quadrangle 8 representing the current pose of the calibration plate 6 in the screen of the computer 5 to be overlapped with the perspective projection quadrangle 9 representing the target pose of the calibration plate 6 by changing the pose of the calibration plate 6 in the hand, enabling the computer 5 to store an image of the calibration plate 6 acquired by the visual laser detector 1 at the current pose and an image of a laser line emitted by the visual laser detector 1 projected on the calibration plate 6 after the perspective projection quadrangles are overlapped, and enabling the screen of the computer 5 to automatically display the perspective projection quadrangle 9 of the next target pose after the image of the previous target pose is stored;
step three, repeatedly executing the step two until all target poses preset in the step one are traversed;
extracting position coordinates of the feature points in the stored images, obtaining the equivalent focal length of the lens of the binocular camera 1-1, the coordinates of the projection point of the optical axis of the lens of the binocular camera 1-1 on the images and the distortion coefficient of the lens of the binocular camera 1-1 by using the coordinates of the feature points in the coordinate system of the calibration plate 6 and adopting a Zhang Zhengyou calibration method, and obtaining a rotation matrix and a translation matrix between the binocular camera 1-1 by adopting the binocular calibration method;
and step five, extracting the position coordinates of the laser line 7 in all the stored images, and obtaining the plane equation of the laser line 7 by adopting a binocular calibration method.
For the motion track calibration of the visual laser detector 1, the calibration method of the automatic three-dimensional laser scanner comprises the following steps:
adjusting a guide rail 2 to a movement zero position, aligning a calibration plate 6 to a visual laser detector 1, identifying and extracting feature points on the calibration plate 6 by the visual laser detector 1, and calculating a rotation matrix and a translation matrix between a coordinate system of the calibration plate 6 and a coordinate system of the visual laser detector 1 by using the feature points;
keeping the calibration plate 6 in an original static state, starting the guide rail 2, driving the visual laser detector 1 to move along a linear direction by the guide rail 2, and continuously calculating the coordinates of the origin of the coordinate system of the visual laser detector 1 in the coordinate system of the calibration plate 6 at each moment in the movement process of the visual laser detector 1 to obtain a group of three-dimensional coordinate data;
and step three, performing linear fitting on the three-dimensional coordinate data to obtain a linear direction vector, and transforming the direction vector from the coordinate system of the calibration plate 6 to the coordinate system of the visual laser detector 1 when the guide rail 2 is located at the movement zero position by using a rotation matrix and a translation matrix between the coordinate system of the calibration plate 6 and the coordinate system of the visual laser detector 1 when the guide rail 2 is located at the movement zero position, which are obtained by calculation, so as to obtain the movement track of the visual laser detector 1.
In the technical scheme, a coordinate system of the visual laser detector 1 takes a center connecting line of a binocular camera 1-1 of the visual laser detector 1 as a Y axis, a midpoint of the center connecting line of the binocular camera 1-1 of the visual laser detector 1 as an origin, the Y axis and an incident light axis of the binocular camera 1-1 form a YOZ coordinate plane, the Z axis is in the same direction as the incident light of the binocular camera 1-1, the X axis is vertical to the YOZ coordinate plane, and the directions of the X axis, the Y axis and the Z axis accord with right-hand rules;
in the above technical solution, as shown in fig. 4, the calibration plate 6 is a flat plate with a plurality of feature points attached to the surface, the feature points are points that can be recognized by the vision laser detector 1, and coordinates of all the feature points on the calibration plate 6 in the coordinate system of the calibration plate 6 are known.
In the above technical solution, the method for acquiring the perspective projection quadrangle 8 of the calibration plate 6 in the current pose includes the following steps:
1) Identifying and extracting feature points on the calibration plate 6
A binocular camera 1-1 of the visual laser detector 1 synchronously acquires images on a current pose calibration plate 6 and transmits the images to a computer 5, the computer 5 respectively identifies all characteristic points in left and right viewpoint images, and the coordinates of each characteristic point in a coordinate system of the visual laser detector 1 are calculated according to polar constraint and a triangulation principle;
2) Calculating a rotation matrix and a translation matrix between a coordinate system of the current pose calibration plate 6 and a coordinate system of the visual laser detector 1
Calculating a rotation matrix and a translation matrix between a coordinate system of the current pose calibration plate 6 and a coordinate system of the visual laser detector 1 by using coordinates of the same group of feature points in the coordinate system of the visual laser detector 1 and coordinates of the same group of feature points in a coordinate system of the current pose calibration plate 6 by adopting a least square method;
3) Computing perspective projection points of four corners of a calibration plate
The method comprises the steps of calculating coordinates of four corners of a current pose calibration plate 6 in a coordinate system of a visual laser detector 1 by utilizing a rotation matrix and a translation matrix between the coordinate system of the current pose calibration plate 6 and the coordinate system of the visual laser detector 1, establishing a perspective projection model in the coordinate system of the visual laser detector 1, wherein a projection plane is an XOY plane, a projection center and the calibration plate 6 are positioned on two sides of the projection plane, the distance from the projection center to the projection plane is set as the focal length of a lens of a binocular camera 1-1 (or other values can be set according to display requirements, and the value only influences the integral scaling of a perspective projection quadrangle and does not influence the using effect of the invention).
In the above technical solution, the method for acquiring the perspective projection quadrangle 9 of the calibration plate 6 at the target pose includes the following steps:
1) Calculating a rotation matrix and a translation matrix between a coordinate system of the target pose calibration plate 6 and a coordinate system of the visual laser detector 1
Calculating a rotation matrix and a translation matrix between the coordinate system of the target pose calibration plate 6 and the coordinate system of the visual laser detector 1 by using the coordinates of the same group of characteristic points in the coordinate system of the visual laser detector 1 and the coordinates in the coordinate system of the target pose calibration plate 6 by using a least square method;
2) Calculating perspective projection points of four corners of the calibration board
The method comprises the steps of calculating coordinates of four corners of a target pose calibration plate 6 in a coordinate system of a visual laser detector 1 by utilizing a rotation matrix and a translation matrix between the coordinate system of the target pose calibration plate 6 and the coordinate system of the visual laser detector 1, establishing a perspective projection model in the coordinate system of the visual laser detector 1, enabling projection planes to be XOY planes, enabling a projection center and the calibration plate 6 to be located on two sides of the projection plane, enabling the distance from the projection center to the projection plane to be equal to the distance from the projection center to the projection plane when the perspective projection points of the four corners of the current pose calibration plate are calculated, projecting the coordinates of the four corners of the target pose calibration plate 6 in the coordinate system of the visual laser detector 1 onto the projection plane according to the constructed perspective projection model, obtaining two-dimensional coordinate values of the four projection points, and sequentially connecting the four projection points to obtain a perspective projection quadrangle 9 of the calibration plate 6 in the target pose.
It should be understood that the above embodiments are only examples for clearly illustrating the present invention, and are not intended to limit the present invention. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications of the invention may be made without departing from the spirit or scope of the invention.
Claims (9)
1. The calibration method of the automatic three-dimensional laser scanner is characterized by comprising the following steps:
presetting a plurality of target poses of a calibration plate (6) in a coordinate system of a visual laser detector (1);
selecting a target pose, enabling the visual laser detector (1) to be in a static state, enabling an operator to hold the calibration plate (6) to move towards the target pose, displaying a perspective projection quadrangle (8) of the calibration plate (6) at the current pose on a screen of the computer (5) in real time, enabling the operator to use two perspective projection quadrangles on the screen of the computer (5) as prompt information when the calibration plate (6) reaches a perspective projection quadrangle (9) of the target pose, enabling the perspective projection quadrangle (8) representing the current pose of the calibration plate (6) in the screen of the computer (5) to coincide with the perspective projection quadrangle (9) representing the target pose of the calibration plate (6) by changing the pose of the calibration plate (6) in the hand, and storing an image of the calibration plate (6) collected by the visual laser detector (1) at the current pose and an image of a laser line emitted by the visual laser detector (1) projected on the calibration plate (6) by the computer (5) after the coincidence;
step three, repeatedly executing the step two until all target poses preset in the step one are traversed, and calibrating the visual laser detector (1) by using all stored images;
the coordinate system of the visual laser detector (1) takes a central connecting line of a binocular camera (1-1) of the visual laser detector (1) as a Y axis, a midpoint of the central connecting line of the binocular camera (1-1) of the visual laser detector (1) as an origin, the Y axis and an incident light axis of the binocular camera (1-1) form a YOZ coordinate plane, the Z axis and incident light of the binocular camera (1-1) are in the same direction, the X axis is perpendicular to the YOZ coordinate plane, and the directions of the X axis, the Y axis and the Z axis accord with right hand rules;
the calibration plate (6) is a flat plate with a plurality of characteristic points attached to the surface, the characteristic points are points which can be recognized by the visual laser detector (1), and the coordinates of all the characteristic points on the calibration plate (6) in the coordinate system of the calibration plate (6) are known.
2. The method for calibrating an automated three-dimensional laser scanner according to claim 1, characterized in that the method for acquiring the perspective projection quadrilateral (8) of the calibration plate (6) in the current pose comprises the following steps:
1) Identifying and extracting feature points on a calibration plate (6)
A binocular camera (1-1) of the visual laser detector (1) synchronously acquires images on a current pose calibration plate (6) and transmits the images to a computer (5), the computer (5) respectively identifies all feature points in left and right viewpoint images, and the coordinates of each feature point in a coordinate system of the visual laser detector (1) are calculated according to polar constraint and a triangulation principle;
2) Calculating a rotation matrix and a translation matrix between a coordinate system of the current pose calibration plate (6) and a coordinate system of the visual laser detector (1)
Calculating a rotation matrix and a translation matrix between the coordinate system of the current pose calibration plate (6) and the coordinate system of the visual laser detector (1) by using the coordinates of the same group of characteristic points in the coordinate system of the visual laser detector (1) and the coordinates in the coordinate system of the current pose calibration plate (6) by adopting a least square method;
3) Calculating perspective projection points of four corners of the calibration board
The method comprises the steps of calculating coordinates of four corners of a current pose calibration plate (6) in a coordinate system of a visual laser detector (1) by utilizing a rotation matrix and a translation matrix between the coordinate system of the current pose calibration plate (6) and the coordinate system of the visual laser detector (1), establishing a perspective projection model in the coordinate system of the visual laser detector (1), wherein a projection plane is an XOY plane, a projection center and the calibration plate (6) are positioned on two sides of the projection plane, projecting the coordinates of the four corners of the current pose calibration plate (6) in the coordinate system of the visual laser detector (1) onto the projection plane according to the established perspective projection model to obtain two-dimensional coordinate values of four projection points, and sequentially connecting the four projection points to obtain a perspective projection quadrangle (8) of the calibration plate (6) in the current pose.
3. The calibration method of an automated three-dimensional laser scanner according to claim 2, wherein in the step 3), the distance from the projection center to the projection plane is set as a focal length of a lens of the binocular camera (1-1).
4. The method for calibrating an automated three-dimensional laser scanner according to claim 1, characterized in that the method for acquiring the perspective projection quadrilateral (9) of the calibration plate (6) in the target pose comprises the following steps:
1) Calculating a rotation matrix and a translation matrix between a coordinate system of the target pose calibration plate (6) and a coordinate system of the visual laser detector (1)
Calculating a rotation matrix and a translation matrix between the coordinate system of the target pose calibration plate (6) and the coordinate system of the visual laser detector (1) by using the coordinates of the same group of characteristic points in the coordinate system of the visual laser detector (1) and the coordinates in the coordinate system of the target pose calibration plate (6) by using a least square method;
2) Computing perspective projection points of four corners of a calibration plate
The method comprises the steps of calculating coordinates of four corners of a target pose calibration plate (6) in a coordinate system of a visual laser detector (1) by utilizing a rotation matrix and a translation matrix between the coordinate system of the target pose calibration plate (6) and the coordinate system of the visual laser detector (1), establishing a perspective projection model in the coordinate system of the visual laser detector (1), wherein a projection plane is an XOY plane, a projection center and the calibration plate (6) are positioned on two sides of the projection plane, projecting the coordinates of the four corners of the target pose calibration plate (6) in the coordinate system of the visual laser detector (1) onto the projection plane according to the established perspective projection model to obtain two-dimensional coordinate values of four projection points, and sequentially connecting the four projection points to obtain a perspective projection quadrangle (9) of the calibration plate (6) in the target pose.
5. The calibration method of an automated three-dimensional laser scanner according to claim 4, wherein in the step 2), the distance from the projection center to the projection plane is set as a focal length of a lens of the binocular camera (1-1).
6. The method for calibrating an automated three-dimensional laser scanner according to claim 1, characterized in that in the second step, the computer (5) displays the target poses in a preset order, and when the image of the last target pose is saved, the computer (5) screen automatically displays the perspective projection quadrilateral (9) of the next target pose.
7. The method for calibrating an automated three-dimensional laser scanner according to claim 1, wherein in the third step, the calibration of the visual laser detector is performed by using all the saved images, and the method comprises the following steps:
1) Extracting position coordinates of feature points in all stored images in the images, obtaining an equivalent focal length of a lens of the binocular camera (1-1), a projection point coordinate of an optical axis of the lens of the binocular camera (1-1) on the images and a distortion coefficient of the lens of the binocular camera (1-1) by using a Zhang Zhengyou calibration method and obtaining a rotation matrix and a translation matrix between the binocular camera (1-1) by using a binocular calibration method by using coordinates of the feature points in a coordinate system of a calibration plate (6);
2) And extracting the position coordinates of the laser lines (7) in all the stored images, and obtaining a plane equation of the laser lines (7) by adopting a binocular calibration method.
8. The calibration method of the automatic three-dimensional laser scanner is characterized by comprising the following steps:
adjusting a guide rail (3) to a movement zero position, aligning a calibration plate (6) to a visual laser detector (1), identifying and extracting characteristic points on the calibration plate (6) by the visual laser detector (1), and calculating a rotation matrix and a translation matrix between a coordinate system of the calibration plate (6) and a coordinate system of the visual laser detector (1) by using the characteristic points;
keeping the calibration plate (6) in an original static state, starting the guide rail (3), driving the visual laser detector (1) to move along a linear direction by the guide rail (3), and continuously calculating the coordinate of the origin of the coordinate system of the visual laser detector (1) in the coordinate system of the calibration plate (6) at each moment in the movement process of the visual laser detector (1) to obtain a group of three-dimensional coordinate data;
performing linear fitting on the three-dimensional coordinate data to obtain a linear direction vector, and transforming the direction vector from the coordinate system of the calibration plate (6) to the coordinate system of the visual laser detector (1) when the guide rail (3) is located at the movement zero position by using a rotation matrix and a translation matrix between the coordinate system of the calibration plate (6) and the coordinate system of the visual laser detector (1) when the guide rail (3) is located at the movement zero position, so as to obtain the movement track of the visual laser detector (1);
the coordinate system of the visual laser detector (1) takes a central connecting line of a binocular camera (1-1) of the visual laser detector (1) as a Y axis, a midpoint of the central connecting line of the binocular camera (1-1) of the visual laser detector (1) as an origin, the Y axis and an incident light axis of the binocular camera (1-1) form a YOZ coordinate plane, the Z axis and incident light of the binocular camera (1-1) are in the same direction, the X axis is perpendicular to the YOZ coordinate plane, and the directions of the X axis, the Y axis and the Z axis accord with right hand rules;
the calibration plate is a flat plate with a plurality of characteristic points attached to the surface, the characteristic points are points which can be identified by the visual laser detector (1), and the coordinates of all the characteristic points on the calibration plate in a calibration plate coordinate system are known.
9. Method for the calibration of an automated three-dimensional laser scanner according to claim 1 or 8, characterized in that it comprises a vision laser detector (1), a guide rail (3), a support structure (3), a controller (4) and a computer (5); visual laser detector (1) comprises binocular camera (1-1) and laser instrument (1-2) that can launch a laser line or many parallel laser lines, visual laser detector (1) is installed on guide rail (3), install guide rail (3) on bearing structure (3), guide rail (3) are connected with detector (1), computer (5) all link to each other with controller (4), visual laser detector (1), and computer (5) are through the start-up, stop and the resetting of control controller (4) control guide rail (3), and linear motion is done along guide rail (3) to visual laser detector (1), and visual laser detector (1) gathers the image and transmits to in computer (5), and computer (5) are to the image display of gathering, save and handle.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116959349A (en) * | 2023-09-20 | 2023-10-27 | 深圳市宝溢显示技术有限公司 | Control system and method of laser display equipment |
| CN117066702A (en) * | 2023-08-25 | 2023-11-17 | 上海频准激光科技有限公司 | Laser marking control system based on laser |
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2022
- 2022-11-18 CN CN202211445083.6A patent/CN115682937A/en active Pending
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117066702A (en) * | 2023-08-25 | 2023-11-17 | 上海频准激光科技有限公司 | Laser marking control system based on laser |
| CN117066702B (en) * | 2023-08-25 | 2024-04-19 | 上海频准激光科技有限公司 | Laser marking control system based on laser |
| CN116959349A (en) * | 2023-09-20 | 2023-10-27 | 深圳市宝溢显示技术有限公司 | Control system and method of laser display equipment |
| CN116959349B (en) * | 2023-09-20 | 2023-11-24 | 深圳市宝溢显示技术有限公司 | Control system and method of laser display equipment |
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