CN115420196B - A universal three-dimensional object measurement method and device - Google Patents

Abstract

The invention relates to the field of three-dimensional measurement, and in particular to a universal object three-dimensional measurement method and device. The universal object three-dimensional measurement method includes: using the object to be measured to obtain a basic image of the object to be measured based on an initial position; The three-dimensional measurement data of the object to be measured is obtained by describing the basic image of the object to be measured. It is processed by collecting multi-angle image data of the object to be measured. It has strong versatility and can achieve three-dimensional reconstruction for transparent, diffuse reflection, high reflection or surfaces of different materials, while improving It improves the efficiency of measurement identification, reduces costs, and effectively improves the reconstruction accuracy of the measurement system based on a simple and effective calibration idea.

Description

A universal three-dimensional object measurement method and device

Technical field

The invention relates to the field of three-dimensional measurement, and in particular to a universal three-dimensional object measurement method and device.

Background technique

Warehousing of items is an important part of a manufacturer's operating costs. Take item display as an example. At present, before items are stored or displayed in large supermarkets, operators generally measure the length, width, height and other geometric dimensions of each type of item and enter them into the system. The product location is calculated optimally by the system. In the past, operators often used calipers for manual measurement. Although only one item of each type needed to be measured, because supermarkets purchased so many new items every day, the workload was quite large, resulting in increased labor costs. In addition to supermarkets, other manufacturers with warehouse management needs are in urgent need of low-cost, universal and rapid measurement methods and equipment that can provide three-dimensional dimensions.

Contents of the invention

In view of the shortcomings of the existing technology, the present invention provides a universal three-dimensional object measurement method and device, which processes the image of the object to be measured to obtain measurement data through a method of small hole imaging and determining a standard rotation axis.

In order to achieve the above objectives, the present invention provides a universal three-dimensional object measurement method, including:

S1. Use the object to be tested to obtain the basic image of the object to be tested based on its initial position;

S2. Use the basic image of the object to be measured to obtain three-dimensional measurement data of the object to be measured.

S2-1. Use the basic image of the object to be measured to obtain the basic visual cone through reverse tracing based on the small hole model;

S2-2. Use the basic visual cone to rotate 5° based on the standard rotating axis to obtain a rotating visual cone;

S2-3. Use the object to be measured to rotate 5° based on the fixed axis to obtain the object image of the current viewing angle;

S2-4. Use the object image of the current perspective to obtain the visual cone of the current perspective through reverse tracing based on the small hole model;

S2-5. Use the visual cone of the current perspective and the rotating visual cone to perform intersection processing to obtain the cone intersection area of the current perspective, and use the cone intersection area of the current perspective as the basis for the next adjacent rotation. visual cone;

S2-6. After repeating steps S2-3 to S2-5 for a total of 70 times, the intersection cone point cloud of the object to be measured is obtained;

S2-7. Use the intersecting cone point cloud of the object to be measured to obtain the three-dimensional contour of the object to be measured based on the α-shape algorithm;

S2-8. Use the image of the three-dimensional contour of the object to be measured to obtain the three-dimensional measurement data of the object to be measured based on the minimum bounding box algorithm.

Preferably, the rotating visual cone obtained by rotating the basic visual cone by 5° based on the standard axis of rotation includes:

Use the reference sphere for calibration to obtain the standard axis;

Use the basic visual cone to rotate 5° based on the standard axis to obtain a rotating visual cone;

Wherein, the diameter range of the reference sphere is 5mm-20mm.

Further, the calibration process using a reference sphere to obtain a standard rotating axis includes:

Utilize the reference sphere to perform backlight photography processing every 5° of rotation based on the initial position to obtain a set of reference sphere rotation images;

Use the reference sphere rotation image set to obtain the two-dimensional outline pixel coordinates of the reference sphere based on the Sobel operator;

Utilize the two-dimensional outline pixel coordinates of the reference sphere to perform fitting processing based on the least squares method to obtain the two-dimensional pixel coordinates of the center of the reference sphere;

Using the two-dimensional pixel coordinates of the center of the reference sphere to obtain the pixel diameter of the reference sphere;

Calculate the scale factor using the pixel diameter of the reference sphere and the actual diameter of the reference sphere;

Calculate the three-dimensional coordinates of the center of the reference sphere using the scale factor;

Use the three-dimensional coordinates of the center of the reference sphere at the initial position and the rotation angle to obtain the three-dimensional coordinates of the rotation of the center of the reference sphere;

The standard rotation axis is calculated based on the nonlinear iterative optimization method using the three-dimensional rotation coordinates of the reference sphere center and the three-dimensional coordinates of the reference sphere center.

Further, the calculation formula for calculating the scale factor using the pixel diameter of the reference sphere and the actual diameter of the reference sphere is as follows:

Among them, s is the scale factor, D is the actual diameter of the reference sphere, and d is the pixel diameter of the reference sphere.

Further, using the scale factor to calculate the three-dimensional coordinates of the center of the reference sphere, the calculation formula is as follows:

Among them, (x _i , y _i , z _i ) are the three-dimensional coordinates of the center of the reference sphere in the camera coordinate system, s is the scale factor, A is the internal parameter of the camera, and (u _i , vi ₎ are the two-dimensional pixel coordinates of the center of the reference sphere. .

Further, using the three-dimensional coordinates of the center of the reference sphere at the initial position and the rotation angle to obtain the three-dimensional coordinates of the rotation of the center of the reference sphere include:

Use the datum sphere to obtain the formal unit vector;

Using the formal unit vectors, obtain a formal unit vector cross product matrix;

The formal unit vector cross product matrix is used to calculate the three-dimensional coordinates of the rotation center of the reference sphere based on the number of rotations.

Furthermore, the formula for calculating the three-dimensional coordinates of the center of rotation of the reference sphere based on the number of rotations using the formal unit vector cross product matrix is as follows:

Among them, (x _k , y _k , z _k ) are the three-dimensional coordinates of the center pixel of the reference sphere rotation, L is the unit matrix, θ _k is the angle after k times of 5° rotation, M is the cross product matrix of the formal unit vector, ( x ₁ , y ₁ , z ₁ ) are the three-dimensional coordinates of the center of the reference sphere at the initial position.

Further, the calculation formula of the standard rotation axis is calculated based on the nonlinear iterative optimization method using the three-dimensional coordinates of the rotation of the center of the reference sphere and the three-dimensional coordinates of the center of the reference sphere as follows:

Among them, p is the standard axis of rotation, (x _i , y _i , z _i ) are the three-dimensional coordinates of the center of the base sphere in the camera coordinate system, and (x _k , y _k , z _k ) are the three-dimensional coordinates of the center pixel of the base sphere's rotation sphere.

Based on the same inventive concept, the present invention also provides a universal three-dimensional object measurement device, including:

Rotating turntable, used to place the object to be measured or the reference sphere;

A camera to acquire an image of the reference sphere on the backlight plate;

A backlight panel, used to receive the image of the object to be measured or the reference sphere;

The rotating turntable is disposed on the side close to the backlight plate, and the reference sphere is disposed in the center of the rotating turntable.

Compared with the closest existing technology, the present invention has the following beneficial effects:

By collecting multi-angle image data of the object to be measured for processing, it has strong versatility and can achieve three-dimensional reconstruction for transparent, diffuse reflection, high reflection or surfaces of different materials. It also improves the efficiency of measurement and identification and reduces costs. Based on simple and effective The calibration idea effectively improves the reconstruction accuracy of the measurement system.

Description of the drawings

Figure 1 is a flow chart of a universal three-dimensional object measurement method provided by the present invention;

Figure 2 is a schematic diagram of a universal three-dimensional object measurement device provided by the present invention;

Reference signs:

1. Rotating turntable; 2. Camera; 3. Backlight plate; 4. Object to be measured; 5. Reference sphere; 6. Camera support plate; 7. Bottom plate; 8. Rib plate; 9. Side plate.

Detailed ways

The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments These are some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

Example 1:

The present invention provides a universal three-dimensional object measurement method, as shown in Figure 1, including:

S1. Use the object to be tested to obtain the basic image of the object to be tested based on its initial position;

S2. Use the basic image of the object to be measured to obtain three-dimensional measurement data of the object to be measured.

Step S2 specifically includes:

S2-1. Use the basic image of the object to be measured to obtain the basic visual cone through reverse tracing based on the small hole model;

S2-2. Use the basic visual cone to rotate 5° based on the standard rotating axis to obtain a rotating visual cone;

S2-3. Use the object to be measured to rotate 5° based on the fixed axis to obtain the object image of the current viewing angle;

S2-4. Use the object image of the current perspective to obtain the visual cone of the current perspective through reverse tracing based on the small hole model;

S2-5. Use the visual cone of the current perspective and the rotating visual cone to perform intersection processing to obtain the cone intersection area of the current perspective, and use the cone intersection area of the current perspective as the basis for the next adjacent rotation. visual cone;

S2-6. After repeating steps S2-3 to S2-5 for a total of 70 times, the intersection cone point cloud of the object to be measured is obtained;

S2-7. Use the intersecting cone point cloud of the object to be measured to obtain the three-dimensional contour of the object to be measured based on the α-shape algorithm;

S2-8. Use the image of the three-dimensional contour of the object to be measured to obtain the three-dimensional measurement data of the object to be measured based on the minimum bounding box algorithm.

Step S2-2 specifically includes:

S2-2-1. Use the reference sphere for calibration to obtain the standard rotating axis;

S2-2-2. Use the basic visual cone to rotate 5° based on the standard axis to obtain a rotating visual cone;

Wherein, the diameter range of the reference sphere is 5mm-20mm.

Step S2-2-1 specifically includes:

S2-2-1-1. Use the reference sphere to perform backlight photography processing every 5° of rotation based on the initial position to obtain a set of reference sphere rotation images;

S2-2-1-2. Use the reference sphere rotation image set to obtain the two-dimensional outline pixel coordinates of the reference sphere based on the Sobel operator;

S2-2-1-3. Use the two-dimensional outline pixel coordinates of the reference sphere to perform fitting processing based on the least squares method to obtain the two-dimensional pixel coordinates of the center of the reference sphere;

S2-2-1-4. Use the two-dimensional pixel coordinates of the center of the reference sphere to obtain the pixel diameter of the reference sphere;

S2-2-1-5. Calculate the scale factor using the pixel diameter of the reference sphere and the actual diameter of the reference sphere;

S2-2-1-6. Use the scale factor to calculate the three-dimensional coordinates of the center of the reference sphere;

S2-2-1-7. Use the three-dimensional coordinates of the center of the reference sphere at the initial position and the rotation angle to obtain the three-dimensional coordinates of the rotation of the center of the reference sphere;

S2-2-1-8. Calculate the standard rotation axis based on the nonlinear iterative optimization method using the three-dimensional rotation coordinates of the reference sphere center and the three-dimensional coordinates of the reference sphere center.

The calculation formula of step S2-2-1-5 is as follows:

Among them, s is the scale factor, D is the actual diameter of the reference sphere, and d is the pixel diameter of the reference sphere.

In this embodiment, a universal object measurement method, the image outline of the reference sphere must pass through the center of the sphere in space, and the diameters of different cross-sectional profiles passing through the same sphere center must be equal. This is an inevitable result of sharing the center of the sphere, so The scale factor can be calculated directly using the actual diameter of the reference sphere and the pixel diameter of the reference sphere.

The calculation formula of step S2-2-1-6 is as follows:

Among them, (x _i , y _i , z _i ) are the three-dimensional coordinates of the center of the reference sphere in the camera coordinate system, s is the scale factor, A is the internal parameter of the camera, and (u _i , vi ₎ are the two-dimensional pixel coordinates of the center of the reference sphere. .

In this embodiment, a universal three-dimensional object measurement method is provided. The internal parameters corresponding to the three-dimensional coordinate system of the pixel center of the reference sphere are used to calibrate the camera based on the MATLAB camera calibration toolbox.

Step S2-2-1-7 specifically includes:

S2-2-1-7-1. Use the reference sphere to obtain the formal unit vector;

S2-2-1-7-2. Use the formal unit vector to obtain the formal unit vector cross product matrix;

S2-2-1-7-3. Use the formal unit vector cross product matrix to calculate the three-dimensional coordinates of the rotation center of the reference sphere based on the number of rotations.

In this embodiment, a universal three-dimensional object measurement method is provided. The formal unit vector is two hypothetical points on the calibration axis, which facilitates the subsequent calculation of the calibration axis.

The calculation formula of step S2-2-1-7-3 is as follows:

Among them, (x _k , y _k , z _k ) are the three-dimensional coordinates of the center pixel of the reference sphere rotation, L is the unit matrix, θ _k is the angle after k times of 5° rotation, M is the cross product matrix of the formal unit vector, ( x ₁ , y ₁ , z ₁ ) are the three-dimensional coordinates of the center of the reference sphere at the initial position.

The calculation formula of step S2-2-1-8 is as follows:

Among them, p is the standard axis of rotation, (x _i , y _i , z _i ) are the three-dimensional coordinates of the center of the base sphere in the camera coordinate system, and (x _k , y _k , z _k ) are the three-dimensional coordinates of the center pixel of the base sphere's rotation sphere.

Example 2:

The invention provides a universal three-dimensional object measurement device, as shown in Figure 2, including:

Rotating turntable 1, used to place the object to be measured 4 or the reference sphere 5;

Camera 2, used to obtain the image of the reference sphere 5 on the backlight panel 3;

Backlight panel 3, used to receive the image of the object to be measured 4 or the reference sphere 5;

The rotating turntable 1 is arranged on the side close to the backlight plate 3, the reference sphere 5 is arranged in the center of the rotating turntable 1, the bottom plate 7 includes a left bottom plate and a right bottom plate, and the rib 8 includes a left rib and a right rib. The side panel 9 includes a left side panel and a right side panel. The left bottom panel and the left side panel are connected and fixed by the left rib. The backlight panel 3 is arranged on the left rib. The side bottom plate and the right side plate are connected and fixed through the right side plate, and the camera 2 is fixedly arranged on the right side plate through the camera support plate 6 .

Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Thus, the invention may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the invention may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) having computer-usable program code embodied therein.

The present invention is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the application. It will be understood that each process and/or block in the flowchart illustrations and/or block diagrams, and combinations of processes and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing device to produce a machine, such that the instructions executed by the processor of the computer or other programmable data processing device produce a use A device for realizing the functions specified in one process or multiple processes of the flowchart and/or one block or multiple blocks of the block diagram.

These computer program instructions may also be stored in a computer-readable memory that causes a computer or other programmable data processing apparatus to operate in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including the instruction means, the instructions The device implements the functions specified in a process or processes of the flowchart and/or a block or blocks of the block diagram.

These computer program instructions may also be loaded onto a computer or other programmable data processing device, causing a series of operating steps to be performed on the computer or other programmable device to produce computer-implemented processing, thereby executing on the computer or other programmable device. Instructions provide steps for implementing the functions specified in a process or processes of a flowchart diagram and/or a block or blocks of a block diagram.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that the present invention can still be modified. Modifications or equivalent substitutions may be made to the specific embodiments, and any modifications or equivalent substitutions that do not depart from the spirit and scope of the invention shall be covered by the scope of the claims of the invention.

Claims (5)

1. A universal three-dimensional object measurement method, which is characterized by including: S1. Use the object to be tested to obtain the basic image of the object to be tested based on its initial position; S2. Use the basic image of the object to be measured to obtain the three-dimensional measurement data of the object to be measured; S2-1. Use the basic image of the object to be measured to obtain the basic visual cone through reverse tracing based on the small hole model; S2-2. Use the basic visual cone to rotate 5° based on the standard rotating axis to obtain a rotating visual cone; S2-2-1. Use the reference sphere for calibration to obtain the standard rotating axis; S2-2-1-1. Use the reference sphere to perform backlight photography processing every 5° of rotation based on the initial position to obtain a set of reference sphere rotation images; S2-2-1-2. Use the reference sphere rotation image set to obtain the two-dimensional outline pixel coordinates of the reference sphere based on the Sobel operator; S2-2-1-3. Use the two-dimensional outline pixel coordinates of the reference sphere to perform fitting processing based on the least squares method to obtain the two-dimensional pixel coordinates of the center of the reference sphere; S2-2-1-4. Use the two-dimensional pixel coordinates of the center of the reference sphere to obtain the pixel diameter of the reference sphere; S2-2-1-5. Calculate the scale factor using the pixel diameter of the reference sphere and the actual diameter of the reference sphere; S2-2-1-6. Use the scale factor to calculate the three-dimensional coordinates of the center of the reference sphere; S2-2-1-7. Use the three-dimensional coordinates of the center of the reference sphere at the initial position and the rotation angle to obtain the three-dimensional coordinates of the rotation of the center of the reference sphere; S2-2-1-7-1. Use the reference sphere to obtain the formal unit vector; S2-2-1-7-2. Use the formal unit vector to obtain the formal unit vector cross product matrix; S2-2-1-7-3. Use the formal unit vector cross product matrix to calculate the three-dimensional coordinates of the rotation center of the reference sphere based on the number of rotations; The calculation formula for calculating the three-dimensional coordinates of the rotation center of the reference sphere based on the number of rotations using the unit vector cross product matrix of the form is as follows: Among them, (xk, yk, zk) is the three-dimensional coordinates of the center pixel of the reference sphere, L is the unit matrix, θk is the angle after rotating k times 5°, M is the cross product matrix of the formal unit vector, (x1, y1, z1) is the three-dimensional coordinates of the center of the reference sphere at the initial position; S2-2-1-8. Calculate the standard rotation axis based on the nonlinear iterative optimization method using the three-dimensional rotation coordinates of the reference sphere center and the three-dimensional coordinates of the reference sphere center; S2-2-2. Use the basic visual cone to rotate 5° based on the standard axis to obtain a rotating visual cone; Wherein, the diameter range of the reference sphere is 5mm-20mm; S2-3. Use the object to be measured to rotate 5° based on the fixed axis to obtain the object image of the current viewing angle; S2-4. Use the object image of the current perspective to obtain the visual cone of the current perspective through reverse tracing based on the small hole model; S2-5. Use the visual cone of the current perspective and the rotating visual cone to perform intersection processing to obtain the cone intersection area of the current perspective, and use the cone intersection area of the current perspective as the basis for the next adjacent rotation. visual cone; S2-6. After repeating steps S2-3 to S2-5 for a total of 70 times, the intersection cone point cloud of the object to be measured is obtained; S2-7. Use the intersecting cone point cloud of the object to be measured to obtain the three-dimensional contour of the object to be measured based on the α-shape algorithm; S2-8. Use the image of the three-dimensional contour of the object to be measured to obtain the three-dimensional measurement data of the object to be measured based on the minimum bounding box algorithm. 2. A universal object three-dimensional measurement method as claimed in claim 1, characterized in that the calculation formula for calculating the scale factor using the pixel diameter of the reference sphere and the actual diameter of the reference sphere is as follows: Among them, s is the scale factor, D is the actual diameter of the reference sphere, and d is the pixel diameter of the reference sphere. 3. A universal object three-dimensional measurement method as claimed in claim 1, characterized in that the calculation formula for calculating the three-dimensional coordinates of the center of the reference sphere using the scale factor is as follows: Among them, (x _i , y _i , z _i ) are the three-dimensional coordinates of the center of the reference sphere in the camera coordinate system, s is the scale factor, A is the internal parameter of the camera, (u _i , vi ₎ are the two-dimensional pixel coordinates of the center of the reference sphere . 4. A universal object three-dimensional measurement method as claimed in claim 1, characterized in that the standard rotation axis is calculated based on a nonlinear iterative optimization method using the three-dimensional rotation coordinates of the reference sphere center and the three-dimensional coordinates of the reference sphere center. The calculation formula is as follows: Among them, p is the standard axis of rotation, (x _i , y _i , z _i ) are the three-dimensional coordinates of the center of the reference sphere in the camera coordinate system, and (x _k , y _k , z _k ) are the three-dimensional coordinates of the center pixel of the reference sphere's rotation sphere. 5. A device based on the universal three-dimensional object measurement method according to any one of claims 1 to 4, characterized in that it includes: Rotating turntable (1), used to place the object to be measured (4) or the reference sphere (5); Camera (2), used to acquire images of the reference sphere (5) on the backlight plate (3); Backlight panel (3), used to receive the image of the object to be measured (4) or the reference sphere (5); The rotating turntable (1) is arranged on the side close to the backlight plate (3), and the reference sphere (5) is arranged in the center of the rotating turntable (1).