Point cloud acquisition method and application

Abstract

The invention discloses a point cloud acquisition method and application, and belongs to the field of modeling, and an adopted device comprises a base, a gantry moving unit, a pitching adjusting unit, a fifth camera, a rotating unit and a control system. The gantry moving unit comprises two X-axis moving assemblies, a Y-axis moving assembly and a Z-axis moving assembly. The number of the X-axis moving assemblies is two, and the two X-axis moving assemblies are arranged in parallel. The X-axis moving assembly comprises a first support, a first driving motor, a first ball screw, a first lead screw nut, a first guide rail and a first sliding block, and the first support is arranged on the base. According to the method, the point cloud data acquisition process can be simplified, the point cloud acquisition efficiency and effect are improved, the point cloud acquisition is accurate and controllable, and the subsequent 3D modeling efficiency is improved. By adopting the scheme of the invention, the control of the position of the fifth camera, the setting and shooting control of the fifth camera, the display and storage of a point cloud registration result and the display and storage of a feature measurement result can be realized.

Description

Technical Field

[0001] The present invention relates to the field of modeling, and more specifically, to a method and application for obtaining point clouds. More specifically, the present application provides an automatic multi-angle point cloud acquisition device and method, which are involved in the fields of three-dimensional modeling, medical imaging, and robot vision, and can realize automatically moving a 3D camera to take pictures of the surface topography of an object from multiple angles to generate point clouds. Background Art

[0002] In a computer, an image is composed of individual pixel points. Image data is stored in each pixel point, and each pixel point contains information about the object to be measured. In addition to common RGB information or grayscale information, it can also contain other information such as depth information and coordinates. A dataset of points in a certain coordinate system is also called a point cloud. Each point in the point cloud contains rich information, including three-dimensional coordinates X, Y, Z, color, classification value, intensity value, time, and so on. Through high-precision point clouds, the real world can be restored. With the development and popularization of three-dimensional point cloud technology, three-dimensional point cloud image processing technology plays an irreplaceable role in the fields of three-dimensional reconstruction, medical imaging, virtual reality, driverless, etc. Since a three-dimensional scanning device cannot obtain all the point cloud images of the object to be scanned at one time, it is necessary to register the point clouds obtained from different directions into a common coordinate system to obtain all the point cloud data.

[0003] Currently, there are various methods for obtaining point clouds, such as: laser ranging method, three-dimensional scanner method, structured light method, and RGB camera method. Among them, when collecting point cloud data for a specific object in a fixed indoor scene, camera shooting is mostly used. When using camera shooting, the distance and angle between the camera and the object being photographed will have a great impact on the collected data, thereby affecting the efficiency and result of the final 3D reconstruction. When photographing an object with fine features, it is necessary to adjust the distance between the camera and the object being photographed and the shooting angle multiple times; during this process, not only does it need to adjust the camera in three directions of the X, Y, and Z axes by different distances, but also it needs to adjust the shooting surface of the object being photographed. Currently, the adjustment of the shooting angle and distance of the point cloud is manually operated; when changing the shooting angle and distance, it cannot be accurately adjusted; and after changing the object being photographed, there are problems of inconsistent shooting backgrounds, inconsistent shooting angles, and inconsistent shooting distances before and after, which often requires multiple point cloud data collections and relatively complex post-processing.

[0004] Therefore, there is an urgent need for an automatic multi-angle point cloud acquisition device to solve the above problems. Summary of the Invention

[0005] The object of the present invention is to provide a method and application for obtaining point clouds. This application can simplify the process of collecting point cloud data, improve the efficiency and effect of point cloud collection, achieve precise and controllable point cloud collection, and enhance the efficiency of subsequent 3D modeling.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] A method for obtaining point clouds. The device used in this method includes a base, a gantry moving unit, a pitching adjustment unit, a fifth camera, a rotating unit for placing the object to be photographed, and a control system;

[0008] The gantry moving unit includes an X-axis moving component, a Y-axis moving component, and a Z-axis moving component arranged on the base. There are two X-axis moving components, and the two X-axis moving components are arranged parallel to each other;

[0009] The X-axis moving component includes a first support, a first driving motor, a first ball screw, a first screw nut, a first guide rail, and a first slider. The first support is arranged on the base. The first driving motor is arranged on the first support, and the first support can provide support for the first driving motor. There are two first guide rails, and the two first guide rails are arranged parallel to each other on the first support. The first ball screw is connected to the output shaft of the first driving motor, and the first driving motor can drive the first ball screw to rotate. The first screw nut is arranged on the first ball screw, and the first screw nut can move along the axial direction of the first ball screw. The first slider is provided with a first chute that matches the first guide rail. The first slider is slidably connected to the first guide rail through the first chute and can move along the axial direction of the first guide rail. The first slider is connected to the first screw nut, and the first screw nut can drive the first slider to move synchronously;

[0010] The Y-axis moving component includes a second support, a second driving motor, a second ball screw, a second screw nut, a second guide rail, and a second slider. The second support is connected to the first slider, and the first slider can drive the second support to move synchronously. The second driving motor is arranged on the second support, and the second support can provide support for the second driving motor. There are two second guide rails, and the two second guide rails are arranged parallel to each other on the second support. The second ball screw is connected to the output shaft of the second driving motor, and the second driving motor can drive the second ball screw to move. The second screw nut is arranged on the second ball screw, and the second screw nut can move along the axial direction of the second ball screw. The second slider is provided with a second chute that matches the second guide rail. The second slider is slidably connected to the second guide rail through the second chute and can move along the axial direction of the second guide rail. The second slider is connected to the second screw nut, and the second screw nut can drive the second slider to move synchronously; The axial direction of the second ball screw is perpendicular to the axial direction of the first ball screw;

[0011] The Z-axis moving assembly includes a third support, a third driving motor, a third ball screw, a third screw nut, a third guide rail, and a third slider. The third support is connected to the second slider, and the second slider can drive the third support to move synchronously. The third driving motor is arranged on the third support, and the third support can provide support for the third driving motor. There are two third guide rails, and the two third guide rails are arranged parallel to each other on the third support. The third ball screw is connected to the output shaft of the third driving motor, and the third driving motor can drive the third ball screw to move. The third screw nut is arranged on the third ball screw, and the third screw nut can move along the axial direction of the third ball screw. The third slider is provided with a third chute that cooperates with the third guide rail. The third slider is slidably connected to the third guide rail through the third chute, and the third slider can move along the axial direction of the third guide rail. The third slider is connected to the third screw nut, and the third screw nut can drive the third slider to move synchronously; the axial direction of the third ball screw is perpendicular to the axial direction of the second ball screw;

[0012] The pitching adjustment unit is connected to the third slider, and the third slider can drive the pitching adjustment unit to move along the axial direction of the third ball screw. The fifth camera is connected to the pitching adjustment unit, and the pitching adjustment unit can drive the fifth camera to rotate;

[0013] The rotating unit is arranged on the base, and the fifth camera connected to the pitching adjustment unit can take pictures of the object to be photographed arranged on the rotating unit;

[0014] The first driving motor, the second driving motor, the third driving motor, the pitching adjustment unit, the rotating unit, and the fifth camera are respectively connected to the control system;

[0015] It includes the following steps:

[0016] (1) Turn on the binocular structured light camera through the control system. The image information collected by the binocular structured light camera is transmitted to the display device to confirm whether the binocular structured light camera is working properly; if the binocular structured light camera is working properly, perform the operation in step (2);

[0017] (2) After the binocular structured light camera works properly, judge whether the photographed surface of the object photographed by the binocular structured light camera meets the photographing requirements;

[0018] If the photographed surface of the object does not meet the requirements, the control system issues an instruction to the rotating unit, drives the sixth turntable to rotate through the sixth driving motor, thereby driving the object to be photographed to rotate, changing its photographed surface, and then returning to step (2) to make a judgment again;

[0019] If the photographed surface of the object meets the requirements, perform the operation in step (3);

[0020] (3) Determine whether the binocular structured light camera is in the correct shooting position; if the binocular structured light camera is in the correct shooting position, perform the operation in step (5); if the binocular structured light camera is not in the correct shooting position, perform the operation in step (4);

[0021] (4) Determine whether the position of the binocular structured light camera in the X direction is correct. If the position in the X direction is incorrect, the control system issues an instruction to the X-axis moving component to move the first slider to the set position in the X direction, and then return to step (4) to determine again whether the position of the binocular structured light camera in the X direction is correct;

[0022] Determine whether the position of the binocular structured light camera in the Y direction is correct. If the position in the Y direction is incorrect, the control system issues an instruction to the Y-axis moving component to move the second slider to the set position in the Y direction, and then return to step (4) to determine again whether the position of the binocular structured light camera in the Y direction is correct;

[0023] Determine whether the position of the binocular structured light camera in the Z direction is correct. If the position in the Z direction is incorrect, the control system issues an instruction to the Z-axis moving component to move the third slider to the set position in the Z direction, and then return to step (4) to determine again whether the position of the binocular structured light camera in the Z direction is correct;

[0024] Determine whether the shooting pitch angle of the binocular structured light camera is correct. If the shooting pitch angle is incorrect, the control system issues an instruction to the pitch adjustment unit to rotate the binocular structured light camera to the set shooting pitch angle, and then return to step (4) to determine again whether the shooting pitch angle of the binocular structured light camera is correct;

[0025] If the positions of the binocular structured light camera in the X direction, Y direction, Z direction, and shooting pitch angle are all correct, then perform the operation in step (5);

[0026] (5) The control system issues an instruction to the binocular structured light camera to obtain point clouds through shooting by the binocular structured light camera;

[0027] (6) Determine whether the point cloud data obtained in step (5) meets the requirements of 3D reconstruction;

[0028] If the obtained point cloud data does not meet the requirements of 3D reconstruction, return to step (2) and repeat the above operation process of obtaining point clouds;

[0029] If the obtained point cloud data can meet the requirements of 3D reconstruction, perform the operation in step (7);

[0030] (7) Determine whether the point cloud data obtained in step (6) completely captures the surface features of the object being photographed;

[0031] If the acquisition is not complete, return to step (2) and repeat the above operation process for obtaining point cloud;

[0032] If the acquisition is complete, the acquisition process ends and the point cloud data acquisition work is completed.

[0033] The fifth camera is a binocular structured light camera.

[0034] The gantry moving unit further includes a right-angle connecting piece, and the third support and the second slider are connected by the right-angle connecting piece.

[0035] The right-angle connecting piece is in the shape of a right triangle.

[0036] It further includes a fifth connecting piece, and the fifth camera is connected to the pitch adjustment unit through the fifth connecting piece.

[0037] The pitch adjustment unit includes a fourth support for connecting with the third slider, a fourth rotating assembly, a fourth turntable, and a fourth driving motor. The fourth rotating assembly is connected to the fourth support and the fourth support can provide support for the fourth rotating assembly. The fourth rotating assembly is connected to the fourth turntable and the fourth rotating assembly can drive the fourth turntable to rotate. The fourth driving motor is connected to the fourth rotating assembly and the fourth driving motor can provide power for the rotation of the fourth rotating assembly. The fourth driving motor is connected to the control system.

[0038] The fifth camera is connected to the fourth turntable through the fifth connecting piece.

[0039] The rotating unit includes a sixth rotating assembly, a sixth turntable, and a sixth driving motor. The sixth rotating assembly and the sixth driving motor are respectively connected to the base and the base can respectively provide support for the sixth rotating assembly and the sixth driving motor;

[0040] The sixth rotating assembly is connected to the sixth turntable and the sixth rotating assembly can drive the sixth turntable to rotate. The sixth driving motor is connected to the sixth rotating assembly and the sixth driving motor can provide power for the rotation of the sixth rotating assembly.

[0041] It further includes a display device connected to the control system.

[0042] It further includes the processing operation of point cloud data, and the specific operation is as follows:

[0043] a. Preprocessing of point cloud data

[0044] Taking the point cloud data collected in step (7) as a data set, using the RANSAC algorithm to randomly select samples from the data set iteratively and fit the selected samples; by adjusting the threshold and the number of iterations, identifying and removing the background point cloud in the data set to obtain the once-processed point cloud;

[0045] Based on the first-time processed point cloud, according to the actual size of the object, a threshold range slightly smaller than the actual size of the object is set, and the pass-through filter is used to retain the point cloud data within the threshold range to obtain the second-time processed point cloud;

[0046] b. Align using the relationship of the point cloud in the camera coordinate system

[0047] The point cloud data obtained by the fifth camera is the point cloud data generated with the fifth camera as the origin to establish a coordinate system;

[0048] The point cloud obtained in the horizontal direction is denoted as the target point cloud template, and then the point cloud source is obtained in multiple orientations that satisfy point cloud reconstruction;

[0049] Each time the point cloud source is obtained, the vertical angle α, the horizontal angle β, and the displacement d are obtained according to the motion direction and distance, and the point cloud is first rotated and then displaced according to the obtained angles and displacement;

[0050] Therefore, the final transformation matrix is T = R xz ×R d；

[0051] The finally aligned point cloud is: template + source × T 。

[0052] The operation of step b is as follows:

[0053] The point cloud data obtained by the fifth camera is the point cloud data generated with the fifth camera as the origin to establish a coordinate system;

[0054] In the vertical direction, the fifth camera is at point A and point B, and the placement position of the object to be photographed is denoted as point C; the fifth camera takes a picture of point C at point A in the horizontal direction to obtain the target point cloud template; all the subsequent obtained point clouds are aligned with the target point cloud template;

[0055] In the vertical direction, the fifth camera is moved from point A to point B, and the pitch angle of the fifth camera is adjusted by the pitch adjustment unit so that the fifth camera takes a picture of point C at point B to obtain the point cloud source;

[0056] The line connecting point A and point C is denoted as line AC, and the line connecting point B and point C is denoted as line BC. An angle α is formed between line AC and line BC; thus, to align the point cloud source to the coordinate system of the target point cloud template, only need to rotate by an angle α around the X-axis, and the rotation matrix in the vertical direction is as follows:

[0057]

[0058] When the sixth turntable drives the object to be photographed to rotate, the rotation angle is extremely the rotation angle β, and the following rotation matrix in the horizontal direction is obtained:

[0059]

[0060] Combining the rotation angles of the point cloud in the horizontal and vertical directions during point cloud acquisition, the final rotation matrix is obtained:

[0061] R xz =R x (α)×R z (β) ；

[0062] If the gantry moving unit moves a distance d in the Y-axis direction, the displacement matrix is as follows:

[0063]

[0064] Each time the point cloud source is obtained, the vertical angle α, the horizontal angle β, and the displacement d are obtained according to the movement direction and distance. The point cloud is first rotated and then displaced according to the obtained angles and displacement;

[0065] Therefore, the final transformation matrix is: T = R xz ×R d；

[0066] The finally aligned point cloud is: template + source × T 。

[0067] Application of the foregoing point cloud acquisition method.

[0068] Apply this method to the measurement of the point cloud.

[0069] Based on the measured point cloud data, a three-dimensional model is constructed.

[0070] In this application, based on the gantry moving unit, linear movement and positioning in the three directions of the X, Y, and Z axes are realized, and the pitching adjustment function is realized based on the pitching adjustment unit. The object to be photographed is placed on the rotating unit to realize multi-angle photographing. In one example, the host computer control software is written based on C#, and signals are transmitted to the control system through serial communication, and then the point cloud acquisition device is controlled. This application can repeatedly position multiple shooting positions and angles, simplify the shooting process, and improve the acquisition efficiency and point cloud quality.

[0071] In this application, the point cloud acquisition device includes a base, a gantry moving unit, a pitching adjustment unit, a fifth camera, a rotating unit for placing the object to be photographed, and a control system. Through the cooperation of the above parts, the function of automatically acquiring the point cloud at multiple angles is realized.

[0072] In this application, the pitch adjustment unit, as a three-degree-of-freedom moving device, is composed of an X-axis moving component, a Y-axis moving component, and a Z-axis moving component, and can achieve movement in the X, Y, and Z directions. To ensure the stability of the fifth camera during movement, this application uses two X-axis moving components arranged in parallel to operate synchronously, achieving stable operation in the X-axis direction; the Y-axis moving component and the Z-axis moving component are vertically connected through a right-angle connecting piece to achieve stable operation in the Y-axis and Z-axis directions. Using the gantry moving unit of this application, the fifth camera can achieve arbitrary displacement in space, meeting the position transformation requirements when the fifth camera captures point clouds.

[0073] Preferably, the fifth camera is a binocular structured light camera. There are two advantages to obtaining point clouds through a binocular structured light camera in this application: (1) Compared with obtaining point clouds using lasers, the cost of using a binocular structured light camera is lower; (2) It is more convenient to obtain point clouds of fixed objects, and the subsequent data processing is simpler. In one example, during installation, the fifth camera is set on the fifth connecting piece through the positioning holes of the fifth camera, and then fixed on the pitch adjustment unit.

[0074] When obtaining point cloud data, for the integrity of the data, it is necessary to obtain point cloud data from multiple angles, including the need for shooting at pitch angles. To meet this requirement, this application sets the fifth camera on the fourth turntable of the pitch adjustment unit through the fifth connecting piece. At the same time, in terms of spatial position, the fifth camera needs to perform displacement adjustment in the Z-axis direction. Therefore, this application connects the pitch adjustment unit to the Z-axis moving component.

[0075] The fifth camera is fixed through the pitch adjustment unit and the pitch adjustment unit. To photograph all aspects of an object, the object to be photographed is placed on the sixth turntable of the rotation unit. During the process of capturing point clouds by shooting, the rotation unit rotates to a specified angle through the sixth driving motor according to the usage requirements, so as to obtain point cloud data from multiple angles.

[0076] Serial communication modules are respectively designed on the gantry moving unit, the pitch adjustment unit, and the rotation unit to communicate with the control system, transmit signals to control the point cloud, and obtain the corresponding motor movements; and, in the case of not being connected to the host computer, it can be controlled through the buttons on the control board.

[0077] Using the solution of this application, it is possible to achieve the control of the position of the fifth camera, the setting and shooting control of the fifth camera, the display and saving of the point cloud registration results, and the display and saving of the feature measurement results. At the same time, this application can save the spatial position data of the fifth camera. During secondary shooting, it can directly read the data and move it to the specified position saved previously. Description of the Drawings

[0078] The present invention will be described by way of examples with reference to the accompanying drawings, wherein:

[0079] Figure 1 is the flowchart of point cloud data acquisition.

[0080] Figure 2 is the assembly drawing of the point cloud acquisition device.

[0081] Figure 3 is the assembly drawing of the gantry moving unit.

[0082] Figure 4 is the schematic diagram of the combination of the fifth camera and the fifth connecting piece.

[0083] Figure 5 is the assembly drawing of the pitch adjustment unit.

[0084] Figure 6 is the assembly drawing of the rotation unit.

[0085] Figure 7 is the schematic diagram of the structure of the Z-axis moving component.

[0086] Figure 8 is the physical object photograph and point cloud diagram of the test piece in Embodiment 1.

[0087] Figure 9 is the preprocessed point cloud effect diagram in Embodiment 1.

[0088] Figure 10 is the schematic diagram of the shooting angle of the vertical camera.

[0089] Figure 11 is the top view schematic diagram of the shooting angle of the horizontal camera.

[0090] Figure 12 is the effect diagram after point cloud alignment in Embodiment 1.

[0091] Markings in the figure: 1. Gantry moving unit, 2. Fifth camera, 3. Pitch adjustment unit, 4. Rotation unit, 5. Base, 11. X-axis moving component, 13. Y-axis moving component, 14. Right-angle connecting piece, 15. Z-axis moving component, 22. Fifth connecting piece, 31. Fourth support, 32. Fourth rotating component, 33. Fourth turntable, 34. Fourth driving motor, 41. Sixth rotating component, 42. Sixth turntable, 43. Sixth driving motor, 51. Third support, 52. Third driving motor, 53. Third ball screw, 54. Third screw nut, 55. Third slider. Detailed implementation manners

[0092] To more clearly illustrate the technical solutions of the embodiments of this specification, the accompanying drawings required for the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some examples or embodiments of this specification. For those of ordinary skill in the art, without creative efforts, this specification can also be applied to other similar scenarios based on these drawings. Unless obvious from the language context or otherwise stated, the same reference numerals in the figures represent the same structure or operation.

[0093] It should be understood that the "system", "device", "unit" and / or "module" used herein is a method for distinguishing different components, elements, parts, portions or assemblies at different levels. However, if other words can achieve the same purpose, the said words can be replaced by other expressions.

[0094] As shown in this specification and the claims, unless the context clearly indicates an exceptional situation, words such as "a", "an", "one" and / or "the" are not specifically singular and may also include the plural. Generally speaking, the terms "comprising" and "including" only indicate the inclusion of the clearly identified steps and elements, and these steps and elements do not constitute an exclusive list. The method or device may also include other steps or elements.

[0095] Flowcharts are used in this specification to illustrate the operations performed by the system according to the embodiments of this specification. It should be understood that the previous or subsequent operations do not necessarily need to be executed precisely in sequence. On the contrary, the steps can be processed in reverse order or simultaneously. At the same time, other operations can also be added to these processes, or one or more steps can be removed from these processes.

[0096] Embodiment 1

[0097] This embodiment mainly realizes the acquisition of the displacements of the fifth camera in the X, Y, and Z directions through the control system to achieve the result of moving in space; after the fifth camera moves to the shooting position, the fourth turntable of the pitch adjustment unit rotates to adjust the pitch angle of the fifth camera for shooting; then, the sixth turntable of the rotation unit rotates the object to be photographed to adjust the shooting plane. After confirming the adjustment is completed, the control system controls the fifth camera to acquire point cloud data.

[0098] As shown in the figure, this example provides a point cloud acquisition device, acquisition method and application. Among them, the point cloud acquisition device includes a base, a gantry moving unit, a pitch adjustment unit, a fifth camera, a rotation unit for placing the object to be photographed, and a control system.

[0099] In this embodiment, the gantry moving unit includes an X-axis moving component, a Y-axis moving component, and a Z-axis moving component disposed on the base. There are two X-axis moving components, and the two X-axis moving components are arranged in parallel with each other. Among them, the X-axis moving component includes a first support, a first driving motor, a first ball screw, a first screw nut, a first guide rail, and a first slider. The first support is disposed on the base, and the first driving motor is disposed on the first support; there are two first guide rails, and the two first guide rails are arranged in parallel on the first support. The first ball screw is connected to the output shaft of the first driving motor, and the first screw nut is disposed on the first ball screw; the first slider is provided with a first chute that cooperates with the first guide rail, and the first slider is slidably connected to the first guide rail through the first chute; the first slider is connected to the first screw nut. In this structure, the first driving motor can drive the first ball screw to rotate, and the first screw nut moves along the axial direction of the first ball screw; the first slider plays a guiding role, and the first screw nut drives the first slider to move synchronously, thereby playing a role in adjusting the X-direction position.

[0100] The Y-axis moving component includes a second support, a second driving motor, a second ball screw, a second screw nut, a second guide rail, and a second slider. The second support is connected to the first slider, and the second driving motor is disposed on the second support; there are two second guide rails, and the two second guide rails are arranged in parallel on the second support. The second ball screw is connected to the output shaft of the second driving motor, the second screw nut is disposed on the second ball screw, the second slider is provided with a second chute that cooperates with the second guide rail, and the second slider is slidably connected to the second guide rail through the second chute; the second slider is connected to the second screw nut. In this embodiment, the axial direction of the second ball screw is perpendicular to the axial direction of the first ball screw. In this structure, the first slider can drive the second support to move synchronously, and the second support can provide support for the second driving motor; the second driving motor can drive the second ball screw to move, and the second screw nut moves along the axial direction of the second ball screw; the second slider can move along the axial direction of the second guide rail, and the second screw nut can drive the second slider to move synchronously.

[0101] The Z-axis moving component includes a third support, a third driving motor, a third ball screw, a third screw nut, a third guide rail, and a third slider. The third support is connected to the second slider, and the third driving motor is arranged on the third support; there are two third guide rails, and the two third guide rails are arranged in parallel on the third support. The third ball screw is connected to the output shaft of the third driving motor, and the third screw nut is arranged on the third ball screw; the third slider is provided with a third chute that cooperates with the third guide rail, and the third slider is slidably connected to the third guide rail through the third chute; the third slider is connected to the third screw nut. In this embodiment, the axial direction of the third ball screw is perpendicular to the axial direction of the second ball screw. In this structure, the second slider can drive the third support to move synchronously, and the third support can provide support for the third driving motor; the third driving motor can drive the third ball screw to move, and the third screw nut can move along the axial direction of the third ball screw; the third slider can move along the axial direction of the third guide rail, and the third screw nut can drive the third slider to move synchronously.

[0102] In this example, the pitching adjustment unit is connected to the third slider, and the third slider can drive the pitching adjustment unit to move along the axial direction of the third ball screw. The fifth camera is connected to the pitching adjustment unit, and the pitching adjustment unit can drive the fifth camera to rotate. The rotating unit is arranged on the base, and the fifth camera connected to the pitching adjustment unit can take pictures of the object to be photographed arranged on the rotating unit. In this embodiment, the first driving motor, the second driving motor, the third driving motor, the pitching adjustment unit, the rotating unit, and the fifth camera are respectively connected to the control system. A display device connected to the control system is also included.

[0103] Furthermore, the fifth camera is selected as a binocular structured light camera. A fifth connecting piece is also included, and the fifth camera is connected to the pitching adjustment unit through the fifth connecting piece. The gantry moving unit also includes a right-angle connecting piece in the shape of a right triangle, and the third support and the second slider are connected through the right-angle connecting piece.

[0104] Furthermore, the pitching adjustment unit includes a fourth support for connecting to the third slider, a fourth rotating component, a fourth turntable, and a fourth driving motor. The fourth rotating component is connected to the fourth support, the fourth rotating component is connected to the fourth turntable, the fourth driving motor is connected to the fourth rotating component, and the fourth driving motor is connected to the control system. In this structure, the fourth support can provide support for the fourth rotating component, the fourth rotating component can drive the fourth turntable to rotate, and the fourth driving motor can provide power for the rotation of the fourth rotating component.

[0105] Further, the rotation unit includes a sixth rotation assembly, a sixth turntable, and a sixth driving motor. The sixth rotation assembly and the sixth driving motor are respectively connected to the base, and the base can respectively provide support for the sixth rotation assembly and the sixth driving motor. The sixth rotation assembly is connected to the sixth turntable, and the sixth rotation assembly can drive the sixth turntable to rotate; the sixth driving motor is connected to the sixth rotation assembly, and the sixth driving motor can provide power for the rotation of the sixth rotation assembly.

[0106] The process of performing point cloud measurement using the aforementioned device is as follows.

[0107] (1) Turn on the binocular structured light camera through the control system. The image information collected by the binocular structured light camera is transmitted to the display device to confirm whether the binocular structured light camera is working properly. If the binocular structured light camera is working properly, proceed to the operation in step (2).

[0108] (2) Determine whether the shooting surface of the object being shot by the binocular structured light camera meets the shooting requirements;

[0109] If the shooting surface of the object being shot does not meet the requirements, the control system issues an instruction to the rotation unit, drives the sixth turntable to rotate through the sixth driving motor, thereby driving the object being shot to rotate, changing its shooting surface, and then returning to step (2) to make the judgment again; if the shooting surface of the object being shot meets the requirements, proceed to the operation in step (3).

[0110] (3) Determine whether the binocular structured light camera is in the correct shooting position; if the binocular structured light camera is in the correct shooting position, proceed to the operation in step (5); if the binocular structured light camera is not in the correct shooting position, proceed to the operation in step (4).

[0111] (4) Determine whether the position of the binocular structured light camera in the X direction is correct. If the position in the X direction is incorrect, the control system issues an instruction to the X-axis moving assembly to move the first slider to the set position in the X direction, and then return to step (4) to determine again whether the position of the binocular structured light camera in the X direction is correct.

[0112] Determine whether the position of the binocular structured light camera in the Y direction is correct. If the position in the Y direction is incorrect, the control system issues an instruction to the Y-axis moving assembly to move the second slider to the set position in the Y direction, and then return to step (4) to determine again whether the position of the binocular structured light camera in the Y direction is correct.

[0113] Determine whether the position of the binocular structured light camera in the Z direction is correct. If the position in the Z direction is incorrect, the control system issues an instruction to the Z-axis moving assembly to move the third slider to the set position in the Z direction, and then return to step (4) to determine again whether the position of the binocular structured light camera in the Z direction is correct.

[0114] Determine whether the shooting pitch angle of the binocular structured light camera is correct. If the shooting pitch angle is incorrect, the control system issues an instruction to the pitch adjustment unit to rotate the binocular structured light camera to the set shooting pitch angle, and then return to step (4) to determine again whether the shooting pitch angle of the binocular structured light camera is correct.

[0115] If the positions of the binocular structured light camera in the X direction, Y direction, and Z direction and the shooting pitch angle are all correct, then perform the operation in step (5).

[0116] (5) The control system issues an instruction to the binocular structured light camera, and obtains point clouds through shooting by the binocular structured light camera.

[0117] (6) Determine whether the point cloud data obtained in step (5) meets the requirements of 3D reconstruction; if the obtained point cloud data does not meet the requirements of 3D reconstruction, then return to step (2) and repeat the above operation process of obtaining point clouds; if the obtained point cloud data can meet the requirements of 3D reconstruction, then perform the operation in step (7).

[0118] (7) Determine whether the point cloud data obtained in step (6) has completely collected the surface features of the object to be photographed; if not completely collected, then return to step (2) and repeat the above operation process of obtaining point clouds; if completely collected, the acquisition process ends and the point cloud data acquisition work is completed.

[0119] The above is the process of obtaining point clouds for an object once. When it is necessary to repeatedly obtain point clouds of the same object multiple times, after the control system records the first shooting position, during subsequent acquisition processes, read the saved position information, and the fifth camera of the point cloud acquisition device automatically moves for shooting.

[0120] This embodiment also provides an operation for processing point cloud data, which includes the following steps.

[0121] a. Preprocessing of point cloud data

[0122] As Figure 8 shown, there is a large amount of background information in the obtained point cloud data, and background information needs to be effectively removed for point cloud alignment. Due to the complex and changeable actual shooting environment, the background information is often closely connected to the target object, which poses a challenge to background recognition.

[0123] In this embodiment, the RANSAC (Random Sample Consensus) algorithm is used to fit and identify the background. The RANSAC algorithm randomly selects samples from the data set in an iterative manner and calculates a mathematical model to fit these samples. By setting appropriate thresholds and the number of iterations, the RANSAC algorithm can effectively identify and remove background point clouds.

[0124] However, even if the background information is successfully removed, there may still be noise points and defects in the point cloud data. These noise points and defects may stem from various reasons, such as sensor noise, environmental interference, object surface reflection characteristics, etc. These noise points and defects not only affect the quality of the point cloud data but may also have a negative impact on subsequent data processing and analysis.

[0125] To remove these noise points and defects, a certain threshold range is set according to the actual size of the object, and the method of Pass-Through Filter is used to retain the point cloud data within the set threshold range, obtaining the secondary processed point cloud. Since most defective point clouds exist in the edge part of the photographed object, in this embodiment, a threshold range slightly smaller than the actual size of the object can be set to ensure that while removing noise points and defects, the complete structure of the object is retained as much as possible, and the processing effect is as Figure 2 shown.

[0126] It should be noted that the setting of the Pass-Through Filter threshold needs to be cautious. If the threshold is set too large, it may cause some edge parts of the object to be deleted by mistake; if the threshold is set too small, the noise points and defects may not be completely removed. Therefore, in this embodiment, it is necessary to set an appropriate threshold range according to the specific object size and the quality of the point cloud data, and optimize the filtering effect through multiple tests and adjustments.

[0127] b. Align using the relationship of the point cloud in the camera coordinate system

[0128] The point cloud data obtained by the fifth camera is generated with the fifth camera as the origin to establish a coordinate system. Therefore, the spatial relationship of the point cloud obtained in the vertical direction is as Figure 3 shown. In the vertical direction, A and B are the camera shooting positions, and C is the position where the object to be photographed is placed. The target point cloud template is obtained at point A, and all the subsequent obtained point clouds are aligned with the template as the target point cloud.

[0129] At point A in the horizontal direction, point C is photographed to obtain the target point cloud template; then, the fifth camera is displaced to point B in the vertical direction through the gantry moving unit, and the camera pitch angle is adjusted by the pitch adjustment unit to photograph point C to obtain the point cloud source. As shown in the figure, the straight line where AC is located and the straight line where BC is located present an included angle α. Therefore, to align the source to the template in its own coordinate system, it only needs to rotate by an angle α around the X axis, and the vertical direction rotation matrix is as follows:

[0130]

[0131] Similarly, the spatial relationship of the point cloud data obtained in the horizontal direction is as Figure 4As shown in the figure. Horizontally, the object to be photographed is driven by the sixth turntable to rotate a certain angle around the Z axis, rotating from position B1 to position B2. It can also be regarded as the fifth camera rotating an angle β relative to the object to be photographed from position A1 to position A2. Therefore, the rotation matrix is as follows:

[0132]

[0133] Combining the rotation angles of the point cloud in the horizontal and vertical directions during point cloud acquisition, the final rotation matrix is obtained:

[0134] R xz =R x (α)×R z (β).

[0135] If the gantry moving unit moves a distance d in the Y-axis direction, the displacement matrix is as follows:

[0136]

[0137] In summary, first, the point cloud obtained horizontally is the target point cloud template, and then the point cloud source is obtained at multiple orientations that satisfy point cloud reconstruction. Each time the source is obtained, the vertical angle α, the horizontal angle β, and the displacement d are calculated according to the movement direction and distance. The point cloud is first rotated and then displaced according to the calculated angles and displacement.

[0138] Therefore, the final transformation matrix is T = R xz ×R d .

[0139] The finally aligned point cloud is: template + source × T.

[0140] The effect diagram after point cloud alignment is as shown in Figure 12 .

[0141] The basic concepts have been described above. Obviously, for those skilled in the art, the above detailed disclosure is only an example and does not constitute a limitation to this specification. Although not explicitly stated here, those skilled in the art may make various modifications, improvements, and corrections to this specification. Such modifications, improvements, and corrections are proposed in this specification, so such modifications, improvements, and corrections still fall within the spirit and scope of the exemplary embodiments of this specification.

[0142] In the meantime, this specification uses specific terms to describe the embodiments of this specification. For example, "an embodiment", "one embodiment", and / or "some embodiments" mean a certain feature, structure, or characteristic related to at least one embodiment of this specification. Therefore, it should be emphasized and noted that "an embodiment" or "one embodiment" or "an alternative embodiment" mentioned twice or more at different positions in this specification does not necessarily refer to the same embodiment. In addition, certain features, structures, or characteristics in one or more embodiments of this specification can be appropriately combined.

[0143] It should be noted that, in order to simplify the presentation disclosed in this specification and thus help the understanding of one or more embodiments, in the foregoing description of the embodiments of this specification, sometimes multiple features are grouped into one embodiment, drawing, or description thereof. However, this disclosure method does not mean that the features required by the subject matter of this specification are more than those mentioned in the claims. In fact, the features of the embodiments are fewer than all the features of the individual embodiments disclosed above.

Claims

1. A method for obtaining point cloud, characterized in that, The device adopted by this method includes a base, a gantry moving unit, a pitching adjustment unit, a fifth camera, a rotating unit for placing the object to be photographed, and a control system; The gantry moving unit includes an X-axis moving component, a Y-axis moving component, and a Z-axis moving component arranged on the base. There are two X-axis moving components, and the two X-axis moving components are arranged in parallel with each other; The X-axis moving component includes a first support, a first driving motor, a first ball screw, a first screw nut, a first guide rail, and a first slider. The first support is arranged on the base. The first driving motor is arranged on the first support, and the first support can provide support for the first driving motor. There are two first guide rails, and the two first guide rails are arranged in parallel on the first support. The first ball screw is connected to the output shaft of the first driving motor, and the first driving motor can drive the first ball screw to rotate. The first screw nut is arranged on the first ball screw, and the first screw nut can move along the axial direction of the first ball screw. The first slider is provided with a first chute that cooperates with the first guide rail. The first slider is slidably connected to the first guide rail through the first chute and can move along the axial direction of the first guide rail. The first slider is connected to the first screw nut, and the first screw nut can drive the first slider to move synchronously; The Y-axis moving component includes a second support, a second driving motor, a second ball screw, a second screw nut, a second guide rail, and a second slider. The second support is connected to the first slider, and the first slider can drive the second support to move synchronously. The second driving motor is arranged on the second support, and the second support can provide support for the second driving motor. There are two second guide rails, and the two second guide rails are arranged in parallel on the second support. The second ball screw is connected to the output shaft of the second driving motor, and the second driving motor can drive the second ball screw to move. The second screw nut is arranged on the second ball screw, and the second screw nut can move along the axial direction of the second ball screw. The second slider is provided with a second chute that cooperates with the second guide rail. The second slider is slidably connected to the second guide rail through the second chute and can move along the axial direction of the second guide rail. The second slider is connected to the second screw nut, and the second screw nut can drive the second slider to move synchronously; The axial direction of the second ball screw is perpendicular to the axial direction of the first ball screw; The Z-axis moving component includes a third support, a third driving motor, a third ball screw, a third screw nut, two third guide rails, and a third slider. The third support is connected to the second slider, and the second slider can drive the third support to move synchronously. The third driving motor is arranged on the third support, and the third support can provide support for the third driving motor. The two third guide rails are arranged on the third support in parallel. The third ball screw is connected to the output shaft of the third driving motor, and the third driving motor can drive the third ball screw to move. The third screw nut is arranged on the third ball screw and can move along the axial direction of the third ball screw. The third slider is provided with a third chute that cooperates with the third guide rail. The third slider is slidably connected to the third guide rail through the third chute and can move along the axial direction of the third guide rail. The third slider is connected to the third screw nut, and the third screw nut can drive the third slider to move synchronously. The axial direction of the third ball screw is perpendicular to the axial direction of the second ball screw. The pitching adjustment unit is connected to the third slider, and the third slider can drive the pitching adjustment unit to move along the axial direction of the third ball screw. The fifth camera is connected to the pitching adjustment unit, and the pitching adjustment unit can drive the fifth camera to rotate. The rotating unit is arranged on the base, and the fifth camera connected to the pitching adjustment unit can take pictures of the object to be photographed arranged on the rotating unit. The first driving motor, the second driving motor, the third driving motor, the pitching adjustment unit, the rotating unit, and the fifth camera are respectively connected to the control system. It includes the following steps: (1) Turn on the binocular structured light camera through the control system. The image information collected by the binocular structured light camera is transmitted to the display device to confirm whether the binocular structured light camera is working properly. If the binocular structured light camera is working properly, perform the operation in step (2). (2) After the binocular structured light camera works properly, judge whether the shooting surface of the object to be photographed by the binocular structured light camera meets the shooting requirements. If the shooting surface of the object to be photographed does not meet the requirements, the control system issues an instruction to the rotating unit, drives the sixth turntable to rotate through the sixth driving motor, and then drives the object to be photographed to rotate, changing its shooting surface, and then return to step (2) to make a judgment again. If the shooting surface of the object to be photographed meets the requirements, perform the operation in step (3). (3) Judge whether the binocular structured light camera is in the correct shooting position. If the binocular structured light camera is in the correct shooting position, perform the operation in step (5). If the binocular structured light camera is not in the correct shooting position, perform the operation in step (4). (4) Judge whether the position of the binocular structured light camera in the X direction is correct. If the position in the X direction is incorrect, the control system issues an instruction to the X-axis moving component to make the first slider move to the set position in the X direction, and then return to step (4) to judge again whether the position of the binocular structured light camera in the X direction is correct. Judge whether the position of the binocular structured light camera in the Y direction is correct. If the position in the Y direction is incorrect, the control system sends an instruction to the Y-axis moving component to move the second slider to the set position in the Y direction, and then returns to step (4) to judge again whether the position of the binocular structured light camera in the Y direction is correct; Judge whether the position of the binocular structured light camera in the Z direction is correct. If the position in the Z direction is incorrect, the control system sends an instruction to the Z-axis moving component to move the third slider to the set position in the Z direction, and then returns to step (4) to judge again whether the position of the binocular structured light camera in the Z direction is correct; Judge whether the shooting pitch angle of the binocular structured light camera is correct. If the shooting pitch angle is incorrect, the control system sends an instruction to the pitch adjustment unit to rotate the binocular structured light camera to the set shooting pitch angle, and then returns to step (4) to judge again whether the shooting pitch angle of the binocular structured light camera is correct; If the positions of the binocular structured light camera in the X direction, Y direction, Z direction, and the shooting pitch angle are all correct, then perform the operation in step (5); (5) The control system sends an instruction to the binocular structured light camera to obtain point cloud data by shooting with the binocular structured light camera; (6) Judge whether the point cloud data obtained in step (5) meets the requirements of 3D reconstruction; If the obtained point cloud data does not meet the requirements of 3D reconstruction, then return to step (2) and repeat the above operation process of obtaining point cloud; If the obtained point cloud data can meet the requirements of 3D reconstruction, then perform the operation in step (7); (7) Judge whether the surface features of the photographed object have been completely collected from the point cloud data obtained in step (6); If not completely collected, then return to step (2) and repeat the above operation process of obtaining point cloud; If the collection is complete, the collection process ends and the point cloud data collection work is completed.

2. The point cloud acquisition method according to claim 1, wherein The fifth camera is a binocular structured light camera.

3. The point cloud acquisition method according to claim 1, wherein It further includes a fifth connecting piece, and the fifth camera is connected to the pitch adjustment unit through the fifth connecting piece.

4. The point cloud acquisition method according to any one of claims 1-3, characterized in that, The pitch adjustment unit includes a fourth support seat, a fourth rotating component, a fourth turntable, and a fourth driving motor for connecting with the third slider. The fourth rotating component is connected to the fourth support seat and the fourth support seat can provide support for the fourth rotating component. The fourth rotating component is connected to the fourth turntable and the fourth rotating component can drive the fourth turntable to rotate. The fourth driving motor is connected to the fourth rotating component and the fourth driving motor can provide power for the rotation of the fourth rotating component. The fourth driving motor is connected to the control system.

5. The point cloud acquisition method according to claim 4, wherein The fifth camera is connected to the fourth turntable through the fifth connecting piece.

6. The point cloud acquisition method according to any one of claims 1-5, characterized in that, The rotating unit includes a sixth rotating component, a sixth turntable, and a sixth driving motor. The sixth rotating component and the sixth driving motor are respectively connected to the base and the base can respectively provide support for the sixth rotating component and the sixth driving motor; The sixth rotating component is connected to the sixth turntable and the sixth rotating component can drive the sixth turntable to rotate. The sixth driving motor is connected to the sixth rotating component and the sixth driving motor can provide power for the rotation of the sixth rotating component.

7. The point cloud acquisition method according to any one of claims 1-6, characterized in that It further includes a display device connected to the control system.

8. Application of the point cloud acquisition method according to any one of claims 1-7.

9. The application according to claim 8, wherein Apply this method to the measurement of point clouds.

10. The application according to claim 9, wherein Construct a three-dimensional model based on the measured point cloud data.

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