CN212229689U - Three-dimensional calibration plate suitable for laser 3D vision - Google Patents
Three-dimensional calibration plate suitable for laser 3D vision Download PDFInfo
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- CN212229689U CN212229689U CN202020643015.0U CN202020643015U CN212229689U CN 212229689 U CN212229689 U CN 212229689U CN 202020643015 U CN202020643015 U CN 202020643015U CN 212229689 U CN212229689 U CN 212229689U
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Abstract
The application provides a three-dimensional calibration plate suitable for laser 3D vision, for the image acquisition object of line laser scanning 3D camera, apply to mechanical 3D vision field, the plate body of calibration plate itself has camera benchmark portion, view concatenation portion and coordinate location portion, through foretell camera benchmark portion, view concatenation portion and coordinate location portion to solve camera shooting through camera benchmark portion and need X direction and the highly vertically camera calibration problem of Y direction, solve camera shooting precision and the inversely proportional problem of field of vision through image concatenation, solve the image through the coordinate system conversion of coordinate location portion to the camera and get the point at actual product image, then the corresponding problem of guide equipment actual execution on the product.
Description
Technical Field
The application relates to the technical field of mechanical 3D vision, in particular to a three-dimensional calibration plate suitable for laser 3D vision.
Background
The existing line laser scanning 3D camera image capturing action is to perform continuous image acquisition on a scanning object only by performing linear scanning action through movement so as to form a three-dimensional point cloud image, the image acquisition action is as shown in figure 1, and the line laser scanning 3D camera performs accurate linear movement along the Y direction;
after the three-dimensional point cloud image is scanned, the shape of the image is highly consistent with that of the scanned object, so that the scanned object can be directly subjected to secondary processing, such as size detection, defect detection or positioning and guiding for cutting, grinding or spraying; however, under the condition that the line laser scanning 3D camera meets the project requirements while acquiring images, the following conditions need to be met:
1. the X direction of the camera shooting is vertical to the Y direction because the height is kept vertical, such as the vertical relation between the X direction and the Y direction in the attached figure 1;
2. the camera is generally in inverse proportion to two parameters of precision and field of view, for example, as shown by a dotted line in fig. 1, the wider the dotted line is spread, the larger the field of view shot by the camera is, but the resolution is correspondingly reduced, that is, the larger the field of view is, the lower the precision is, and the more the field of view is, the more the precision is, the more the project needs to be, and the high precision is required, the complete situation cannot be considered;
3. when the camera scans an object, because a virtual 3D coordinate is built in the camera and the object is imaged in the 3D coordinate, but the virtual coordinate built in the camera cannot determine the position of the camera on the mechanical coordinate of the equipment, the equipment guiding action cannot be carried out on the object;
typically, the above conditions are met for each item, only if the error produced is within acceptable limits. But this greatly limits the maximum performance of the line laser scanning 3D camera hardware and generates a lot of resource waste.
SUMMERY OF THE UTILITY MODEL
The three-dimensional calibration plate aims at achieving the technical effects of laser 3D vision hardware calibration, image splicing and coordinate system conversion, aims at solving the problem that camera shooting needs the X direction and the Y direction highly-vertical calibration, solves the problem that camera shooting precision and a visual field are in inverse proportion through image splicing, solves the problem of fixed point operation shooting through coordinate system conversion, and provides the three-dimensional calibration plate suitable for laser 3D vision.
The application adopts the following technical means for solving the technical problems:
the application provides a three-dimensional calibration plate suitable for laser 3D vision, which is an image acquisition object of a line laser scanning 3D camera, the plate body of the calibration plate is provided with a camera reference part, a view splicing part and a coordinate positioning part, wherein,
the camera reference part is positioned on one side of the plate body of the calibration plate and is provided with a first reference inclined plane block, a second reference inclined plane block and a reference plane block, the first reference inclined plane block and the second reference inclined plane block are fixedly arranged on two sides of the reference plane block, inclined planes of the first reference inclined plane block and the second reference inclined plane block have preset inclination and are opposite in direction, and the inclined planes of the first reference inclined plane block and the second reference inclined plane block and the plane of the reference plane block mutually form a trapezoidal shape;
the view splicing part is provided with a first splicing groove position, a second splicing groove position and a circular hole array, the circular hole array penetrates through the middle position of a plate body of the calibration plate and is arranged on the calibration plate at the two side positions of the circular hole array, the first splicing groove position and the second splicing groove position are respectively provided with a first splicing inclined surface and a second splicing inclined surface, the inclined surfaces of the first splicing inclined surface and the second splicing inclined surface have preset inclination degrees but opposite directions, and the first splicing groove position and the second splicing groove position are arranged on the calibration plate through a triangular groove formed by intersecting the first splicing inclined surface and the second splicing inclined surface;
the coordinate positioning part comprises a plurality of positioning columns, small holes are formed in the top surfaces of the positioning columns, and the positioning columns are fixed to the positions of the angular points of the calibration plate respectively.
Further, the first reference inclined plane block and the second reference inclined plane block have the same inclined plane inclination but opposite directions, and mutually form an isosceles trapezoid shape with the plane of the reference plane block.
Furthermore, the slope inclination of the first splicing slope and the slope inclination of the second splicing slope are equal but opposite, and the first splicing groove and the second splicing groove are arranged on the calibration plate through isosceles triangle grooves formed by the intersection of the first splicing slope and the second splicing slope.
Furthermore, the first splicing slot position and the second splicing slot position are respectively arranged at two sides of the circular hole array and are perpendicular to the camera reference part.
Furthermore, the first splicing slot position and the second splicing slot position are provided with a plurality of triangular grooves which are spliced with each other.
Furthermore, openings are respectively formed in the middle parts of the first splicing groove and the second splicing groove in a penetrating mode.
The application provides a three-dimensional calibration system suitable for laser 3D vision, comprising a line laser scanning 3D camera, a motion mechanism and the three-dimensional calibration plate suitable for laser 3D vision;
the motion mechanism drives the line laser scanning 3D camera to perform linear motion;
the calibration plate is positioned below the laser acquisition end of the line laser scanning 3D camera;
and the line laser scanning 3D camera collects the image of the calibration plate to carry out camera calibration, splicing calibration and coordinate calibration.
The application also provides a camera calibration method of the three-dimensional calibration plate suitable for laser 3D vision, and the step of collecting the image of the calibration plate by a line laser scanning 3D camera to calibrate the camera comprises the following steps:
s11, the camera scans a first reference inclined plane of a first reference inclined plane block, a reference plane of a reference plane block and a second reference inclined plane of a second reference inclined plane block of the calibration plate along a straight line in sequence so as to acquire imaging graphs of the first reference inclined plane, the reference plane and the second reference inclined plane in sequence;
s12, processing the imaging graphs of the first reference inclined plane, the reference plane and the second reference inclined plane by using a virtual imaging model preset in the camera to obtain the acquisition length of the reference plane in the imaging graphs;
s13, judging whether the acquisition length is consistent with the actual length of the reference plane;
s14, if not, proceeding the next step, if yes, judging that the cameras are absolutely parallel;
s15, determining the deviation angle coefficient of the acquisition length and the actual length;
and S16, performing corresponding position adjustment on the camera according to the deviation angle coefficient.
Further, the step of acquiring an image of the calibration plate by the line laser scanning 3D camera for stitching calibration includes:
s21, when the camera moves to the first splicing groove, the camera scans a first splicing inclined plane and a second splicing inclined plane of the first splicing groove of the calibration plate along a straight line to obtain an imaging picture of the first splicing inclined plane and the second splicing inclined plane of the first splicing groove;
s22, when the camera moves to the circular hole array, the camera scans the circular holes of each row of the circular hole array along a straight line to obtain the imaging graph of each row of the circular holes, and gradually compares whether the imaging graphs of each row of the circular holes are completely overlapped with the straight line motion of the camera, and outputs the circular hole splicing result;
s23, when the camera moves to the second splicing groove, the camera scans the first splicing inclined plane and the second splicing inclined plane of the second splicing groove of the calibration plate along a straight line to obtain the imaging graphs of the first splicing inclined plane and the second splicing inclined plane of the second splicing groove, then judges whether the imaging graphs of the first splicing inclined plane and the second splicing inclined plane of the first splicing groove are completely overlapped with the imaging graphs of the first splicing inclined plane and the second splicing inclined plane of the second splicing groove, and outputs the groove splicing result;
s24, if the round hole splicing result and the slot splicing result are completely overlapped, judging that the camera cannot generate visual angle deviation in the linear moving process, and if not, carrying out the next step;
s25, obtaining a first deviation value of the comparison between the round hole images of the rows in step S22, obtaining an image of the first splice slope and the second splice slope of the first splice slot in step S23, and obtaining a second deviation value of the comparison between the image of the first splice slope and the second splice slope of the second splice slot;
and S26, correspondingly adjusting the camera according to the first deviation value and the second deviation value.
Further, the step of acquiring an image of the calibration plate by the line laser scanning 3D camera for coordinate calibration includes:
s31, the camera scans the positioning columns on the angular point positions of the calibration plate in sequence to obtain the imaging images of the positioning columns;
s32, a virtual 3D coordinate is arranged in the camera, the Y axis of the virtual 3D coordinate is the linear motion direction of the camera, the X axis is perpendicular to the Y axis, the imaging graph of the positioning column is placed in the virtual 3D coordinate, and a marking point is formed in the virtual 3D coordinate according to the small hole in the top surface of the positioning column;
and S33, correspondingly controlling the camera by the motion mechanism for controlling the movement of the camera according to the punctuations formed in the virtual 3D coordinates.
The application provides a three-dimensional calibration plate suitable for laser 3D vision has following beneficial effect:
the application provides a three-dimensional calibration plate suitable for laser 3D vision, which is an image acquisition object of a line laser scanning 3D camera, wherein a plate body of the calibration plate is provided with a camera reference part, a view splicing part and a coordinate positioning part, the camera reference part is positioned on one side of the plate body of the calibration plate and is provided with a first reference inclined plane block, a second reference inclined plane block and a reference plane block, the first reference inclined plane block and the second reference inclined plane block are fixedly arranged on two sides of the reference plane block, inclined planes of the first reference inclined plane block and the second reference inclined plane block have preset inclination, but are opposite in direction and mutually form a trapezoidal shape with a plane of the reference plane block, and hardware calibration of the camera 3D vision is realized through the camera reference part; the view splicing part is provided with a first splicing groove position, a second splicing groove position and a circular hole array, the circular hole array penetrates through the middle position of a plate body of the calibration plate, the first splicing groove position and the second splicing groove position are respectively arranged on the calibration plate at two side positions of the circular hole array, the first splicing groove position and the second splicing groove position are respectively provided with a first splicing inclined surface and a second splicing inclined surface, the inclined surfaces of the first splicing inclined surface and the second splicing inclined surface have preset inclination degrees but opposite directions, the first splicing groove position and the second splicing groove position are arranged on the calibration plate through a triangular groove formed by intersecting the first splicing inclined surface and the second splicing inclined surface, and calibration of camera image splicing is realized through the first splicing groove position, the second splicing groove position and the circular hole array; the coordinate positioning part comprises a plurality of positioning columns, small holes are formed in the top surfaces of the positioning columns, the positioning columns are respectively fixed at the positions of the angular points of the calibration plate, and the inside of the camera is calibrated with 3D coordinates through the positioning columns, so that the camera can be controlled in the later period conveniently; in conclusion, the problem that the camera shooting needs to be calibrated in a way that the height of the X direction is vertical to that of the Y direction is solved, the problem that the camera shooting precision is inversely proportional to the visual field is solved through image splicing, and the problem of fixed-point operation shooting is solved through coordinate system conversion.
Drawings
FIG. 1 is a schematic diagram of a prior art camera movement position;
FIG. 2 is a schematic structural diagram of an embodiment of a three-dimensional calibration plate suitable for laser 3D vision according to the present application;
FIG. 3 is a schematic structural diagram of a three-dimensional calibration plate suitable for laser 3D vision according to another embodiment of the present disclosure;
FIG. 4 is a schematic structural diagram of an embodiment of a three-dimensional calibration plate and a camera moving direction suitable for laser 3D vision according to the present disclosure;
FIG. 5 is a perspective view of one embodiment of a side of a three-dimensional calibration plate suitable for laser 3D vision as proposed in the present application;
FIG. 6 is a block diagram of a three-dimensional calibration system suitable for laser 3D vision according to an embodiment of the present disclosure;
fig. 7 is a schematic view illustrating a camera calibration flow in an embodiment of a camera calibration method of a three-dimensional calibration plate suitable for laser 3D vision according to the present disclosure;
fig. 8 is a schematic view of camera stitching calibration in an embodiment of a camera calibration method for a three-dimensional calibration plate suitable for laser 3D vision provided in the present application;
fig. 9 is a schematic diagram illustrating a coordinate calibration process in an embodiment of a camera calibration method of a three-dimensional calibration plate suitable for laser 3D vision according to the present disclosure;
the implementation, functional features and advantages of the present application will be further explained with reference to the accompanying drawings.
Detailed Description
It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
It is noted that the terms "comprises," "comprising," and "having" and any variations thereof in the description and claims of this application and the drawings described above are intended to cover non-exclusive inclusions. For example, a process, method, system, article, or apparatus that comprises a list of steps or elements is not limited to only those steps or elements listed, but may alternatively include other steps or elements not listed, or inherent to such process, method, article, or apparatus. In the claims, the description and the drawings of the specification of the present application, relational terms such as "first" and "second", and the like, may be used solely to distinguish one entity/action/object from another entity/action/object without necessarily requiring or implying any actual such relationship or order between such entities/actions/objects.
Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearances of the phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. It is explicitly and implicitly understood by one skilled in the art that the embodiments described herein can be combined with other embodiments.
Referring to fig. 2 and fig. 3, a schematic structural diagram of a three-dimensional calibration plate suitable for laser 3D vision in an embodiment of the present application is shown;
the three-dimensional calibration plate suitable for laser 3D vision is an image acquisition object of a line laser scanning 3D camera;
the plate body of the calibration plate is provided with a camera reference part 1, a view splicing part 2 and a coordinate positioning part 3, as shown by a dotted line in the attached figure 2.
Wherein the content of the first and second substances,
the camera reference part 1 is positioned on one side of the plate body of the calibration plate and is provided with a first reference inclined plane block 11, a second reference inclined plane block 13 and a reference plane block 12, the first reference inclined plane block 11 and the second reference inclined plane block 13 are fixedly arranged on two sides of the reference plane block 12, inclined planes of the first reference inclined plane block 11 and the second reference inclined plane block 13 have preset inclination and are opposite in direction to each other, and the inclined planes of the first reference inclined plane block 11 and the second reference inclined plane block 13 and the plane of the reference plane block 12 form a trapezoidal shape;
in a preferred embodiment, the slopes of the first reference slope block 11 and the second reference slope block 13 are equal in slope but opposite in direction to each other to form an isosceles trapezoid shape with the plane of the reference plane block 12.
As shown in fig. 3, three terrace-like protruding portions are provided on the camera reference portion 1 on one side of the plate body of the calibration plate, and it should be noted that, in some expandable cases, the number of the terrace-like protruding portions can be set; a convex portion thereof is constituted by the first reference slope block 11, the second reference slope block 13 and the reference plane block 12.
Specifically, the camera reference part 1 of the calibration board is used for calibrating whether the cameras are absolutely parallel, firstly, a reference plane grinding machine of a reference plane block 12 of the calibration board needs to be processed until the flatness is within 0.01mm, the flatness is an inclination coefficient of the reference plane, a dial indicator is adopted to calibrate the reference plane, so that the cameras are parallel to the reference plane, then, the detection is carried out, the inclined plane of a first reference inclined plane block 11 and the inclined plane of a second reference inclined plane block 13 are used for measurement, it can be understood that the two inclined planes are arranged on two sides of the reference plane, at the moment, the acquisition length of the reference plane is calculated through a virtual imaging model inside the cameras, and the acquisition length calculation mode of the virtual imaging model is as follows:
(1) extending the two bevels until the two bevels intersect (see FIG. 5);
(2) a triangular algorithm is built in the virtual imaging model, and the extension lengths of the two inclined planes are led into the triangular algorithm, so that the length of the plane is calculated, and the acquisition length of the reference plane is acquired.
After the camera obtains the above-mentioned acquisition length, it needs to compare with the actual length of the reference plane of the calibration board, that is, the acquisition length is compared with the actual length, for example, the acquisition length is 11cm, and the actual length is 10cm, it can be determined that the camera is inclined, and then the corresponding camera adjustment is performed.
The beneficial points are that: the measurement method can avoid measurement errors caused by the limitation of X resolution of the line laser scanning camera, and the imaging principle has the highest resolution and repeatability in the Z direction, so the highest performance of the camera can be exerted by the calculation; the line laser scanning cameras on the market use the imaging principle of a laser triangulation method, and directly scan the length of a triangular reference plane, so that the length cannot be well determined by the cameras due to the influence of the resolution of the cameras, the scanned length is inaccurate, and the comparison result of the length and the actual length is also inaccurate.
The calibration plate is also provided with a view splicing part 2 which comprises a first splicing groove 21, a second splicing groove 22 and a circular hole array 23, wherein the circular hole array 23 (the circular hole in the range framed and selected by the dotted line in the attached drawing 3 is called the circular hole array 23) penetrates through the middle position of the plate body arranged on the calibration plate, the first splicing groove 21 and the second splicing groove 22 are respectively arranged on the calibration plate at the two sides of the circular hole array 23, the first splicing groove 21 and the second splicing groove 22 are both provided with a first splicing inclined plane and a second splicing inclined plane, the inclined planes of the first splicing inclined plane and the second splicing inclined plane have preset inclination but opposite directions, and the first splicing groove 21 and the second splicing groove 22 are arranged on the calibration plate through a triangular groove formed by intersecting the first splicing inclined plane and the second splicing inclined plane;
in a preferred embodiment, the first and second inclined mating surfaces have equal inclination but opposite directions, and the first and second slots 21 and 22 are formed in the calibration plate by isosceles triangular grooves formed by intersecting the first and second inclined mating surfaces. In addition, the first splicing slot position 21 and the second splicing slot position 22 are respectively arranged at two sides of the circular hole array 23 and are perpendicular to the camera reference part 1. And, the first splicing slot position 21 and the second splicing slot position 22 both have a plurality of triangular grooves spliced with each other.
Specifically, the camera carries out splicing calibration on the scanned images through the view splicing part 2, and the scanned images are synthesized in a collection splicing mode after calibration, so that the problem of inverse ratio of the field of view and the resolution can be effectively solved, and the original performance of the camera is exerted; the first splicing slot 21 and the second splicing slot 22 are respectively disposed at two sides of the circular hole array 23, and the first splicing slot 21 and the second splicing slot 22 are both provided with two triangular grooves located on the calibration board (refer to fig. 2).
Referring to FIG. 4, a schematic diagram of a calibration plate according to an embodiment of the present application is shown;
in the specific implementation process, the camera moves along the Y direction to scan the calibration board, and first obtains an imaging map corresponding to the first reference plane 211, the first splicing slope 212 and the second splicing slope 214 of the first splicing slot position 21, and the second reference plane 213 according to the moving scan; subsequently, the camera scans and acquires a third reference plane 221, a first splicing inclined plane 222, a second splicing inclined plane 224 and a fourth reference plane 223 of the second splicing slot 22, and corresponding imaging images; finally, the imaging graphs of the first reference plane and the third reference plane are overlapped to judge whether the imaging graphs are completely overlapped, the first splicing inclined plane and the second splicing inclined plane of the first splicing groove position 21 are overlapped with the imaging graphs of the first splicing inclined plane and the second splicing inclined plane of the second splicing groove position 22 to judge whether the imaging graphs of the second reference plane and the fourth reference plane are overlapped to judge whether the imaging graphs are completely overlapped; if the overlapping is complete, it is determined that the camera does not have a deviation in the moving process, including a deviation of the upper and lower levels, a deviation in the rotational direction, and the like. If the camera cannot be completely overlapped, the camera is judged to have deviation in the moving process, corresponding adjustment is needed to be carried out, the adjustment comprises manual adjustment and/or mechanical adjustment, and the repeated description is omitted in the application.
It should be noted that the circular hole array 23 is also used for calibrating image stitching, for example, the circular holes in each row are overlapped in fig. 4, which is the same as the above principle and is not described herein again.
The beneficial points are that:
because the intersection characteristics of the space inclined plane and the space plane are that the coplanarity and the contact degree of the two images are most easily identified, the splicing data is adjusted after the difference between the two images is measured, and the calculation process is greatly reduced; the X-direction resolution of the camera itself is limited by the field of view (the X-direction resolution of a camera with a large field of view is reduced. And the position of the central point of the circular hole can be collected by adopting an algorithm after the circular hole is imaged, so that the influence of the resolution ratio in the X direction is subjected to mean calculation by increasing the sampling number (namely the size of the circular hole). And after the end points of the two round holes are captured, calculating a three-dimensional space distance value between the two central points, comparing the three-dimensional space distance value with a theoretical round hole distance in an actual finish machining drawing, and after the three-dimensional space distance value is debugged to possibly be consistent with the theoretical distance, indicating that the image splicing in the X direction is finished. Therefore, the method is adopted to calculate the splicing distance in the X direction, and the influence in the X direction is also reduced to the maximum extent. The images with high precision as far as possible can be spliced out under the limited condition of the line laser scanning camera.
In another embodiment, openings are respectively formed in the middle portions of the first splicing slot 21 and the second splicing slot 22, so that new determination conditions can be introduced and a process of determining whether the two openings are completely overlapped can be performed on the premise of reducing the manufacturing material of the calibration plate.
The calibration plate is further provided with a coordinate positioning part 3 which comprises a plurality of positioning columns 31, small holes 32 are formed in the top surfaces of the positioning columns 31, and the plurality of positioning columns 31 are respectively fixed at the angular point positions of the calibration plate.
Specifically, the coordinate positioning portion 3 is a coordinate system for the calibration camera, it can be understood that a virtual 3D coordinate system is built in the camera, after the camera scans the calibration plate, an imaging image of the calibration plate is imaged on the virtual 3D coordinate system, but at this time, the camera does not know where the camera is located in the coordinate system, the imaging image of the calibration plate is further sent to the moving mechanism by the camera, and the imaging image of the calibration plate is imaged on the moving mechanism, so that the moving mechanism can determine a mechanical coordinate system, a reference number of the camera exists on the coordinate system, and reference numbers of the positioning columns 31 and the small holes 32 of the calibration plate, and the moving mechanism can shoot the specified position of the calibration plate at the fixed point of the camera.
In summary, the present application provides a three-dimensional calibration plate suitable for laser 3D vision, which is an image acquisition object of a line laser scanning 3D camera, where a plate body of the calibration plate itself includes a camera reference portion 1, a view splicing portion 2, and a coordinate positioning portion 3, where the camera reference portion 1 is located on one side of the plate body of the calibration plate, and includes a first reference inclined plane block 11, a second reference inclined plane block 13, and a reference plane block 12, the first reference inclined plane block 11 and the second reference inclined plane block 13 are fixed on two sides of the reference plane block 12, inclined planes of the first reference inclined plane block 11 and the second reference inclined plane block 13 have a preset inclination but have opposite directions to each other to form a trapezoidal shape with a plane of the reference plane block 12, and hardware calibration of the camera 3D vision is implemented by the camera reference portion 1; the view splicing part 2 is provided with a first splicing groove 21, a second splicing groove 22 and a circular hole array 23, the circular hole array 23 penetrates through the middle position of a plate body of the calibration plate, the first splicing groove 21 and the second splicing groove 22 are respectively arranged on the calibration plate at two side positions of the circular hole array 23, the first splicing groove 21 and the second splicing groove 22 are respectively provided with a first splicing inclined surface and a second splicing inclined surface, the inclined surfaces of the first splicing inclined surface and the second splicing inclined surface have preset inclination angles but opposite directions, the first splicing groove 21 and the second splicing groove 22 are arranged on the calibration plate through a triangular groove formed by intersecting the first splicing inclined surface and the second splicing inclined surface, and calibration of camera image splicing is realized through the first splicing groove 21, the second splicing groove 22 and the circular hole array 23; the coordinate positioning part 3 comprises a plurality of positioning columns 31, small holes 32 are formed in the top surfaces of the positioning columns 31, the positioning columns 31 are respectively fixed at the angular point positions of the calibration plate, and 3D coordinates in the camera are calibrated through the positioning columns 31, so that the camera can be controlled in the later period conveniently; in conclusion, the problem that the camera shooting needs to be calibrated in a way that the height of the X direction is vertical to that of the Y direction is solved, the problem that the camera shooting precision is inversely proportional to the visual field is solved through image splicing, and the problem of fixed-point operation shooting is solved through coordinate system conversion.
Referring to fig. 6, it is a block diagram of a three-dimensional calibration system suitable for laser 3D vision, which includes a line laser scanning 3D camera, a motion mechanism and the above three-dimensional calibration board suitable for laser 3D vision;
the movement mechanism drives the line laser scanning 3D camera to perform linear movement;
the calibration plate is positioned below the laser acquisition end of the line laser scanning 3D camera;
and the line laser scanning 3D camera collects the image of the calibration plate to carry out camera calibration, splicing calibration and coordinate calibration.
By the aforesaid, this application is gathered the image of calibration board through the camera and is carried out camera calibration, concatenation calibration and coordinate calibration, consequently:
referring to fig. 7, for the schematic flow chart of the camera calibration method of the three-dimensional calibration plate suitable for laser 3D vision provided in the present application, the step of acquiring the image of the calibration plate by the line laser scanning 3D camera to perform camera calibration includes:
s11, the camera scans the first reference slope of the first reference slope block 11, the reference plane of the reference plane block 12 and the second reference slope of the second reference slope block 13 of the calibration plate along a straight line in sequence to acquire imaging images of the first reference slope, the reference plane and the second reference slope in sequence;
s12, processing the imaging graphs of the first reference inclined plane, the reference plane and the second reference inclined plane by using a virtual imaging model preset in the camera to obtain the acquisition length of the reference plane in the imaging graphs;
s13, judging whether the acquisition length is consistent with the actual length of the reference plane;
s14, if not, proceeding the next step, if yes, judging that the cameras are absolutely parallel;
s15, determining the deviation angle coefficient of the acquisition length and the actual length;
and S16, performing corresponding position adjustment on the camera according to the deviation angle coefficient.
Referring to fig. 8, in order to provide a schematic flowchart of a camera calibration method of a three-dimensional calibration plate suitable for laser 3D vision according to the present application, the step of collecting an image of the calibration plate for stitching calibration by a line laser scanning 3D camera includes:
s21, when the camera moves to the first splicing slot 21, the camera scans the first splicing slope and the second splicing slope of the first splicing slot 21 of the calibration board along a straight line to obtain the imaging images of the first splicing slope and the second splicing slope of the first splicing slot 21;
s22, when the camera moves to the circular hole array 23, the camera scans the circular holes of each row of the circular hole array 23 along a straight line to obtain the imaging graph of each row of the circular holes, and gradually compares whether the imaging graphs of each row of the circular holes are completely overlapped with the straight line motion of the camera, and outputs the circular hole splicing result;
s23, when the camera moves to the second splicing slot 22, the camera scans the first splicing slope and the second splicing slope of the second splicing slot 22 of the calibration board along a straight line to obtain the imaging maps of the first splicing slope and the second splicing slope of the second splicing slot 22, then, determines whether the imaging maps of the first splicing slope and the second splicing slope of the first splicing slot 21 completely coincide with the imaging maps of the first splicing slope and the second splicing slope of the second splicing slot 22, and outputs a slot splicing result;
s24, if the circular hole splicing result and the slot splicing result are completely overlapped, judging that the camera cannot generate visual angle deviation in the linear moving process, and if not, carrying out the next step;
s25, acquiring a first deviation value of the comparison between the round hole images of the rows in step S22, and acquiring a second deviation value of the comparison between the images of the first splice slope and the second splice slope of the first splice slot 21 and the images of the first splice slope and the second splice slope of the second splice slot 22 in step S23;
and S26, correspondingly adjusting the camera according to the first deviation value and the second deviation value.
Referring to fig. 9, for the schematic flowchart of the camera calibration method of the three-dimensional calibration plate suitable for laser 3D vision provided in the present application, the step of acquiring the image of the calibration plate for coordinate calibration by the line laser scanning 3D camera includes:
s31, the camera scans the positioning columns 31 on the positions of the corner points of the calibration plate in sequence to obtain the imaging images of the positioning columns 31;
s32, arranging a virtual 3D coordinate in the camera, setting the Y axis of the virtual 3D coordinate as the linear motion direction of the camera, setting the imaging graph of the positioning column 31 in the virtual 3D coordinate, and forming a punctuation in the virtual 3D coordinate according to the small hole 32 on the top surface of the positioning column 31;
and S33, the motion mechanism for controlling the camera to move correspondingly controls the camera according to the punctuations formed in the virtual 3D coordinates.
Although embodiments of the present application have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the application, the scope of which is defined in the appended claims and their equivalents.
Claims (6)
1. A three-dimensional calibration plate suitable for laser 3D vision is an image acquisition object of a line laser scanning 3D camera, and is characterized in that a plate body of the calibration plate is provided with a camera reference part, a view splicing part and a coordinate positioning part, wherein,
the camera reference part is positioned on one side of the plate body of the calibration plate and is provided with a first reference inclined plane block, a second reference inclined plane block and a reference plane block, the first reference inclined plane block and the second reference inclined plane block are fixedly arranged on two sides of the reference plane block, inclined planes of the first reference inclined plane block and the second reference inclined plane block have preset inclination and are opposite in direction, and the inclined planes of the first reference inclined plane block and the second reference inclined plane block and the plane of the reference plane block mutually form a trapezoidal shape;
the view splicing part is provided with a first splicing groove position, a second splicing groove position and a circular hole array, the circular hole array penetrates through the middle position of a plate body of the calibration plate and is arranged on the calibration plate at the two side positions of the circular hole array, the first splicing groove position and the second splicing groove position are respectively provided with a first splicing inclined surface and a second splicing inclined surface, the inclined surfaces of the first splicing inclined surface and the second splicing inclined surface have preset inclination degrees but opposite directions, and the first splicing groove position and the second splicing groove position are arranged on the calibration plate through a triangular groove formed by intersecting the first splicing inclined surface and the second splicing inclined surface;
the coordinate positioning part comprises a plurality of positioning columns, small holes are formed in the top surfaces of the positioning columns, and the positioning columns are fixed to the positions of the angular points of the calibration plate respectively.
2. The three-dimensional calibration plate suitable for laser 3D vision according to claim 1, wherein the slopes of the first and second reference slope blocks are equal but opposite in direction to form an isosceles trapezoid shape with the plane of the reference plane block.
3. The three-dimensional calibration plate suitable for laser 3D vision according to claim 1, wherein the slope of the first splicing slope and the slope of the second splicing slope are equal but opposite, and the first splicing groove and the second splicing groove are formed on the calibration plate through isosceles triangle grooves formed by the intersection of the first splicing slope and the second splicing slope.
4. The three-dimensional calibration plate suitable for laser 3D vision according to claim 1, wherein the first splicing groove and the second splicing groove are respectively arranged at two sides of the circular hole array and are perpendicular to the camera reference part.
5. The three-dimensional calibration plate suitable for laser 3D vision according to claim 1, wherein the first splicing groove and the second splicing groove are provided with a plurality of triangular grooves spliced with each other.
6. The three-dimensional calibration plate suitable for laser 3D vision according to claim 1, 3, 4 or 5, wherein the middle portions of the first splicing groove and the second splicing groove are respectively provided with an opening in a penetrating way.
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