Photogrammetric apparatus and method for hole spacing

Abstract

The application relates to a hole distance photogrammetric device and method, which comprises a mobile device, a monocular visual identification camera arranged on the mobile device, a binocular camera arranged on the mobile device and opposite to the monocular visual identification camera, and a processing unit used for calculating hole distance according to the collected images of the monocular visual identification camera and the binocular camera. The hole distance measuring range can be effectively expanded, and the accuracy of the hole distance measuring result is improved.

Description

Technical Field

[0001] This invention relates to the field of measurement technology, and specifically to a photogrammetric device and method for aperture spacing. Background Technology

[0002] With increasing demands for precision in complex structural components, high-precision online inspection of complex structures via visual measurement is becoming an indispensable tool in industrial inspection. For the hole spacing between two holes, a binocular camera is used for inspection. However, since complex surface structures may be large-scale, long-sized models, the field of view of the binocular camera with telecentric lens measurement method is relatively small, failing to meet the hole spacing measurement requirements of large-sized structures and making it difficult to guarantee measurement accuracy. Moreover, manual inspection is generally inefficient and inaccurate, making it unsuitable for large-scale, full-volume inspection. Summary of the Invention

[0003] In view of this, the present invention aims to provide a photogrammetric device and method for aperture spacing, which can expand the aperture spacing measurement range and improve the accuracy of the measurement results.

[0004] In a first aspect, a first embodiment of the present invention provides a photogrammetric device for aperture spacing, the device comprising: a moving device; a monocular vision recognition camera disposed on the moving device; a binocular camera disposed on the moving device, wherein the binocular camera and the monocular vision recognition camera are disposed opposite to each other; and a processing unit configured to calculate the aperture spacing based on the images acquired by the monocular vision recognition camera and the binocular camera.

[0005] Preferably, the monocular vision recognition camera and the binocular camera are further integrated with a vision controller, which is connected to the processing unit.

[0006] Preferably, the monocular vision recognition camera is positioned facing the object to be measured.

[0007] In a second aspect, a second embodiment of the present invention provides a photogrammetric method for aperture spacing, utilizing a photogrammetric apparatus for aperture spacing as described in any of the first aspects, the method comprising:

[0008] S100, multiple coding points are pre-set in the calibration field, and the monocular vision recognition camera and the binocular camera are calibrated to the same coordinate system through the multiple coding points. The calibration field includes at least two sets of coding points, the monocular vision recognition camera corresponds to at least one set of coding points, and the binocular camera corresponds to at least one set of coding points.

[0009] S200, the coding point corresponding to the monocular vision recognition camera is removed, and multiple test holes are arranged in the acquisition range of the monocular vision recognition camera. The processing unit controls the moving device to move, so that the monocular vision recognition camera and the binocular camera can acquire images respectively.

[0010] S300, the processing unit calculates the aperture spacing based on the images acquired by the monocular vision recognition camera and the binocular camera.

[0011] Preferably, in step S100:

[0012] Multiple coding points are calibrated to the same coordinate system using the following formula:

[0013]

[0014] Among them, u n and v n M is the image coordinate of the encoded point in the image. i It is a coordinate transformation matrix calculated based on image coordinates and the spatial physical coordinates of the encoded points, p xn p yn and p zn These are the coordinates of the encoded points in a unified coordinate system;

[0015] The structural parameters of the measurement system for the binocular camera are determined according to the following formula:

[0016] (R t) = M Di M D2

[0017] Among them, M D1 M D2 These are the extrinsic parameter matrices of the two cameras of the stereo camera in the unified coordinate system of the encoding point.

[0018] Preferably, in step S200:

[0019] The plurality of holes to be tested are arranged in a straight line, and the arrangement direction is parallel to the movement direction of the moving device.

[0020] Preferably, step S300 includes:

[0021] The monocular vision recognition camera acquires images of the hole to be tested;

[0022] The binocular camera acquires coded point information and converts it into three-dimensional coordinate information;

[0023] The processing unit determines the hole spacing based on the image of the hole to be tested and the three-dimensional coordinate information.

[0024] Preferably, step S300 further includes:

[0025] When the monocular vision recognition camera acquires the center coordinates of the two holes to be tested as (u1, v1) and (u2, v2) respectively, the following relationship is satisfied:

[0026]

[0027] The binocular camera then calculates the spatial physical coordinates of multiple encoded points in the corresponding two apertures to be measured, using the following formula:

[0028]

[0029]

[0030] in, and These are the spatial physical coordinates of the two apertures to be measured in the coordinate system of the binocular camera system, S D1 S D2 These are the intrinsic parameter matrices of the stereo camera;

[0031] The pose matrix of the binocular camera is:

[0032]

[0033] The hole spacing L is:

[0034]

[0035] The embodiments of the present invention combine a monocular vision recognition camera and a binocular camera, and use a mobile device to move and acquire images, which can effectively expand the measurement range of aperture spacing and improve the accuracy of aperture spacing measurement results. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0037] Figure 1 This is a schematic diagram of the calibration scenario for the photogrammetry method for aperture spacing according to an embodiment of the present invention;

[0038] Figure 2 This is a schematic diagram of a measurement scenario for the photogrammetric method for aperture spacing according to an embodiment of the present invention;

[0039] Figure 3 This is a schematic flowchart of the photogrammetry method for aperture spacing according to an embodiment of the present invention. Detailed Implementation

[0040] The description of the embodiments in this specification should be taken in conjunction with the accompanying drawings, which should form part of the complete specification. In the drawings, the shape or thickness of the embodiments may be exaggerated and may be indicated in a simplified or convenient manner. Furthermore, parts of the various structures in the drawings will be described separately; it is worth noting that elements not shown in the figures or not described in words are in a form known to those skilled in the art.

[0041] The descriptions of the embodiments herein, including any references to directions and orientations, are for ease of description only and should not be construed as limiting the scope of the invention. The following description of preferred embodiments involves combinations of features, which may exist independently or in combination; the invention is not particularly limited to the preferred embodiments. The scope of the invention is defined by the claims.

[0042] like Figure 1 As shown, the photogrammetric device for aperture spacing according to an embodiment of the present invention includes: a moving device; a monocular vision recognition camera disposed on the moving device; a binocular camera disposed on the moving device, with the binocular camera positioned opposite to the monocular vision recognition camera; and a processing unit for calculating the aperture spacing based on the images acquired by the monocular vision recognition camera and the binocular camera. Preferably, the monocular vision recognition camera and the binocular camera further integrate a vision controller, which is connected to the processing unit. Preferably, the monocular vision recognition camera is positioned facing the object to be measured.

[0043] like Figures 1-3 As shown, the photogrammetric method for aperture spacing in this embodiment of the invention includes:

[0044] S100, multiple coding points are pre-set in the calibration field, and the multiple coding points are calibrated to the same coordinate system by the monocular vision recognition camera and the binocular camera. The calibration field includes at least two rows of coding points, the monocular vision recognition camera corresponds to at least one row of coding points, and the binocular camera corresponds to at least one row of coding points.

[0045] S200, the coding point corresponding to the monocular vision recognition camera is removed, and multiple test holes are arranged in the acquisition range of the monocular vision recognition camera. The processing unit controls the moving device to move, so that the monocular vision recognition camera and the binocular camera can acquire images respectively.

[0046] S300, the processing unit calculates the aperture spacing based on the images acquired by the monocular vision recognition camera and the binocular camera.

[0047] Specifically, the method includes:

[0048] (1) Positional relationship calibration of monocular vision recognition camera and binocular camera

[0049] First, categorize the two types of cameras as follows: Figure 1 The setup is as shown, fixed to a mobile device. Assuming a large test piece is placed on a wall, a monocular vision camera is set to photograph the wall from the side, while a binocular camera photographs the ground. Encoded points (not on the same straight line) are affixed to the side wall and ground. An overall control field is established. The control field is first photographed using a standard monocular camera to capture the marker point positions, unifying the coordinates of the encoded points on the wall and ground into a single coordinate system. Then, the 3D coordinates of the encoded points in the control field captured by the standard monocular camera are calculated and imported into the software controlling the three cameras as common reference points for calibration and orientation calculations.

[0050] (2) Calculate the hole spacing value of the measured object by taking pictures.

[0051] After the positional relationship of the three cameras is calibrated, the wall coding points are removed. The cameras are connected to the computer via the controller, and the device is started to move in a straight line. During the movement, the cameras are triggered to collect multiple images. The binocular camera takes pictures of the ground, and the monocular recognition camera takes pictures of the circular holes of the object being measured on the wall. The camera recognition software processes the images in real time and extracts the circular holes and their centers from the images. At the same time, it automatically calculates the hole spacing value.

[0052] (3) Hole spacing calibration method

[0053] The circular holes on the object to be measured can be measured in advance using a coordinate measuring machine, the center of the circle can be extracted, and the corresponding hole spacing value can be calculated. This value can be used as a standard value, and the hole spacing value captured by the three cameras can be calibrated with this value.

[0054] The overall system of this invention consists of a monocular vision recognition camera with a telecentric lens and two binocular cameras with ordinary camera lenses, all connected to a controller. A control field is established using coded points in the overall motion environment. The binocular and monocular cameras are fixedly mounted back-to-back on a mobile device (the mobile device moves in a straight line). The positional relationship between the monocular and binocular cameras is pre-calibrated, unifying the coordinates of the coded points in the control field into a single coordinate system. Upon starting the entire device, in motion, the three cameras respectively capture images of the coded points in the control field, and then the camera positions relative to the control field are calculated using post-intersection. Treating each of the three cameras individually, the coordinates of several coded points within the control field are substituted into the following formula:

[0055]

[0056] u n and v n M is the image coordinate of the encoded point in the image. i It is a coordinate transformation matrix calculated based on image coordinates and the spatial physical coordinates of the encoded points, p xnp yn and p zn These are the coordinates of the encoding point in a unified coordinate system.

[0057] The physical coordinates of the encoding points within the control field are in a unified coordinate system. The extrinsic parameter matrices of the stereo camera in the control field coordinate system are M. D1 M D2 The intrinsic parameter matrices are S D1 S D2 The extrinsic parameter matrix of the monocular camera in the control field coordinate system is M. s The three extrinsic parameter matrices are obtained by substituting the physical coordinates of the control field encoding point and its corresponding image coordinates into formula (1) to form a system of equations, thereby obtaining the structural parameters of the binocular camera measurement system as follows:

[0058] (R t) = M D1 M D2

[0059] Regarding the division of labor between the two types of cameras, binocular cameras mainly calculate the three-dimensional coordinate position, while monocular vision recognition cameras mainly capture images of the circular holes in the object being measured. They also need to be used in conjunction with corresponding algorithms, such as recognizing the outline of the circular holes, extracting the center of the circle, and calculating the size. Finally, the hole spacing value of large-sized objects being measured is analyzed and calculated.

[0060] Let the coordinates of the center image of the hole 1 captured by the monocular vision recognition camera be (u1, v1) and the coordinates of the center image of the hole 2 be (u2, v2). When the coordinate relationship between the hole 1 and the hole 2 meets the requirements of formula (2), the corresponding binocular camera image is taken for the next step of calculation.

[0061]

[0062] Based on the control field coding point images captured by the binocular camera system at the locations of the measured hole 1 and the measured hole 2 respectively when the requirements of formula (2) are met, the spatial physical coordinates of several coding points in the binocular camera system coordinate system at the measured hole 1 can be calculated according to formulas (3) and (4). The spatial physical coordinates of the coding point in the binocular camera system coordinate system at the measured hole 2.

[0063]

[0064]

[0065] Based on the principle of common point transformation, the pose matrices of the two control field coordinate systems can be obtained as follows:

[0066]

[0067] Therefore, the measured hole spacing L is:

[0068]

[0069] The embodiments of the present invention combine a monocular vision recognition camera and a binocular camera, and use a mobile device to move and acquire images, which can effectively expand the measurement range of aperture spacing and improve the accuracy of aperture spacing measurement results.

[0070] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A hole distance photogrammetry method using a hole distance photogrammetry device, characterized by, The device comprises: a mobile device; a monocular visual recognition camera arranged on the mobile device; a binocular camera arranged on the mobile device and opposite to the monocular visual recognition camera; a processing unit configured to calculate the inter-bore distance according to the images captured by the monocular visual recognition camera and the binocular camera; the monocular visual recognition camera is arranged towards an object to be measured; The method comprises: S100, a plurality of encoding points are arranged in a calibration field, and the monocular visual recognition camera and the binocular camera are calibrated to the same coordinate system through the plurality of encoding points, wherein the calibration field comprises at least two groups of encoding points, the monocular visual recognition camera corresponds to at least one group of encoding points, and the binocular camera corresponds to at least one group of encoding points; S200, the encoding points corresponding to the monocular visual recognition camera are removed, and a plurality of to-be-measured bores are arranged in the capture range of the monocular visual recognition camera, and the processing unit controls the mobile device to move, thereby driving the monocular visual recognition camera and the binocular camera to capture images respectively; S300, the processing unit calculates the inter-bore distance according to the images captured by the monocular visual recognition camera and the binocular camera; In step S100: a plurality of encoding points are calibrated to the same coordinate system by using the following formula: wherein u n and v n are the corresponding image coordinates of the encoding point in the image, M i is a coordinate transformation matrix calculated from the image coordinates and the spatial physical coordinates of the encoding point, p xn , p yn and p zn are the coordinates of the encoding point in the uniform coordinate system, respectively. Step S300 comprises: the monocular visual recognition camera captures the images of the to-be-measured bores; the binocular camera captures the encoding point information and converts it into three-dimensional coordinate information; the processing unit determines the inter-bore distance according to the images of the to-be-measured bores and the three-dimensional coordinate information; Step S300 further comprises: when the monocular visual recognition camera captures the center coordinates of two to-be-measured bores as (u1, v1) and (u2, v2) respectively, if the following relationship is satisfied: then the binocular camera calculates the spatial physical coordinates of a plurality of encoding points at the corresponding two to-be-measured bores, and the calculation formula is: wherein, and are the spatial physical coordinates of the encoding point in the coordinate system of the binocular camera system of the two holes to be measured, respectively, S D1 , S D2 are the intrinsic matrices of the binocular camera, respectively; M D1 , M D2 are the extrinsic matrices of the two cameras of the binocular camera in the coordinate system of the encoding point, respectively; the pose matrix of the two control field coordinate systems is: then the inter-bore distance L is:

2. The photogrammetric method of hole spacing according to claim 1, characterized in that, The monocular visual recognition camera and the binocular camera are further integrated with a visual controller, and the visual controller is connected with the processing unit.

3. The photogrammetric method of hole spacing according to claim 1, characterized in that, In step S200: a plurality of to-be-measured bores are arranged in a straight line, and the arrangement direction is parallel to the movement direction of the mobile device.

Images