WO2021129305A1

WO2021129305A1 - Calibration rod testing method for optical motion capture system, device, apparatus, and storage medium

Info

Publication number: WO2021129305A1
Application number: PCT/CN2020/132105
Authority: WO
Inventors: 王越; 许秋子
Original assignee: 深圳市瑞立视多媒体科技有限公司
Priority date: 2019-12-26
Filing date: 2020-11-27
Publication date: 2021-07-01
Also published as: CN111127559B; CN111127559A

Abstract

A calibration rod testing method for an optical motion capture system, a device, an apparatus, and a storage medium. The method comprises: acquiring multiple frames of coordinate data from an optical camera capturing a moving calibration rod, determining whether coordinate points in each of the frames have two intersecting lines having a common coordinate point; if so, recording multiple coordinate points on the two intersecting lines as coordinate data having passed inspection; and determining, according to position relationship data of multiple marker points on the calibration rod, multiple coordinate points having positions corresponding to the multiple marker points of the calibration rod from each frame of coordinate data having passed inspection, so as to obtain multiple frames of valid coordinate data. The method determines whether coordinate data acquired by an optical camera comprises calibration rod information, and also accurately obtains coordinate data of multiple coordinate points having a one-to-one correspondence with a calibration rod coordinate system, thereby providing essential information for camera calibration.

Description

Calibration rod detection method, device, equipment and storage medium in optical motion capture system

Technical field

The invention relates to the technical field of computer vision, in particular to a calibration rod detection method, device, equipment and storage medium in an optical motion capture system.

Background technique

With the increasing application of machine vision, there is an increasing demand for multi-camera vision systems in large space environments. The main direction is high-precision positioning and tracking in large spaces. In machine vision applications, in order to determine the relationship between the three-dimensional geometric position of a point on the surface of a space object and its corresponding point in the image, geometric models of camera imaging must be established. These geometric models are camera parameters. These parameters must be obtained through experiments and calculations. The process of solving the parameters is called camera calibration. The traditional camera calibration method needs to use a calibration object with a known size, such as a checkerboard calibration board. By establishing the correspondence between a point with a known coordinate on the calibration object and an image point, a certain algorithm is used to obtain the internal and external parameters of the camera model. In a multi-camera environment, in order to locate and track an object, not only the parameters of each camera must be determined, but also the positional relationship between the camera and the camera must be determined.

The existing checkerboard calibration board algorithm uses strict conditions, and the algorithm time is too long, which is very inconvenient to use. In addition, there are a lot of cameras in the motion capture system, and the area cross relationship between the camera and the camera is complicated, and the checkerboard calibration board requires a lot of manpower and material resources. Obviously, the existing checkerboard calibration method is not suitable for the calibration of optical cameras. Therefore, there is a need for a calibration method that can be used in optical motion capture systems that can accurately and quickly detect and identify.

Summary of the invention

The main purpose of the present invention is to provide a calibration rod detection method, device, equipment and storage medium in an optical motion capture system, aiming to solve the technical problems of detection and identification of the calibration rod in the optical motion capture system.

To achieve the above objective, the present invention provides a calibration rod detection method in an optical motion capture system. The method includes the following steps:

Acquiring multiple frames of coordinate data captured by the optical camera on the swinging calibration rod, and each frame of the coordinate data includes multiple coordinate point information;

In the multi-frame coordinate data, determine whether there are two intersecting straight lines with a common coordinate point formed by a preset number of coordinate points in the plurality of coordinate points in each frame, and if not, remove the coordinate data If the corresponding frame exists, multiple coordinate points on the two intersecting straight lines are recorded as qualified coordinate data to obtain qualified multi-frame coordinate data;

Obtain the positional relationship data of the plurality of marking points on the calibration rod, and determine, according to the positional relationship data, a plurality of coordinate points corresponding to the positions of the plurality of marking points of the calibration rod in each frame of the qualified coordinate data, The multiple coordinate points are recorded as one frame of valid coordinate data, and multiple frames of valid coordinate data are obtained.

Optionally, in the multi-frame coordinate data, it is determined whether there are two intersecting straight lines with a common coordinate point formed by a preset number of coordinate points among the plurality of coordinate points in each frame, if not, Then remove a frame corresponding to the coordinate data, if it exists, record multiple coordinate points on two intersecting straight lines, and before obtaining qualified multi-frame coordinate data, it includes:

In the multi-frame coordinate data, it is determined whether the number of the multiple coordinate points in each frame is within a preset threshold range, and if it is not within the threshold range, then a frame corresponding to the coordinate data is eliminated; Within the threshold range, a plurality of the coordinate points are recorded as qualified coordinate data to obtain qualified multi-frame coordinate data.

Optionally, in the multi-frame coordinate data, it is determined whether there are two intersecting straight lines with a common coordinate point formed by a preset number of coordinate points in the plurality of coordinate points in each frame, if not, Then remove a frame corresponding to the coordinate data, and if it exists, record multiple coordinate points on the two intersecting straight lines as qualified coordinate data to obtain qualified multi-frame coordinate data, including:

In the multi-frame coordinate data, determining whether there is a preset number of coordinate points on the same straight line among the plurality of coordinate points in each frame, and if there is no straight line, then removing a frame corresponding to the coordinate data;

If there are straight lines, continue to determine whether the number of straight lines is within the preset number range, and if it is not within the number range, remove one frame corresponding to the coordinate data;

If it is within the number range, continue to determine whether the coordinate points in the multiple straight lines have a common coordinate point, and if there is no common coordinate point, remove a frame corresponding to the coordinate data;

If there are common coordinate points, continue to determine whether there are only two straight lines with common coordinate points, and if there are more than two straight lines, then remove one frame corresponding to the coordinate data;

If there are only two straight lines, multiple coordinate points on the two intersecting straight lines are recorded as qualified coordinate data, and finally qualified multi-frame coordinate data is obtained.

Optionally, in the multiple frames of coordinate data, determining whether there are a preset number of coordinate points located on the same straight line among the multiple coordinate points in each frame includes:

In one frame of coordinate data, randomly select three of the coordinate points, calculate the pairwise distance between the three coordinate points, and obtain three distance values;

Find the smallest distance value and the second smallest distance value among the three distance values, and determine whether the second smallest distance value is greater than a preset distance threshold. If the second smallest distance value is greater than the distance threshold, then three The coordinate points are not on the same straight line;

Otherwise, judging whether the ratio of the second smallest distance value to the minimum distance value is greater than a preset ratio threshold, and if the ratio is less than or equal to the ratio threshold, the three coordinate points are not on the same straight line;

Otherwise, determine whether the included angle between the vector of the second smallest distance value and the vector of the smallest distance value is less than a preset included angle threshold, and if the included angle is greater than or equal to the included angle threshold, then three The coordinate points are not on the same straight line;

Otherwise, the three coordinate points are located on the same straight line.

Optionally, in the one frame of coordinate data, randomly taking three of the coordinate points, calculating the two-by-two distance between the three coordinate points, and obtaining three distance values, including:

The distance between any two of the three coordinate points is the pixel Euclidean distance of two-dimensional coordinates, and is calculated by using the following formula:

D=sqrt((x1-x2) ² +(y1-y2) ² )

Wherein, D is the distance value, and the two-dimensional coordinates of the two coordinate points are (x1, y1) and (x2, y2).

Optionally, the acquiring positional relationship data of a plurality of marking points on the calibration rod, and determining the positions corresponding to the plurality of marking points of the calibration rod in each frame of coordinate data that are qualified according to the positional relationship data The multiple coordinate points are recorded as one frame of valid coordinate data, and multiple frames of valid coordinate data are obtained, including:

Acquiring positional relationship data of a plurality of marking points on the calibration rod, the positional relationship data including the length of two intersecting line segments formed by the plurality of marking points, an origin mark, and other marking point coordinate data corresponding to the origin mark;

Mark a common coordinate point in two straight lines formed by a plurality of coordinate points in a qualified frame of coordinate data as an origin coordinate, and the origin coordinate corresponds to the origin mark;

Calculate a target line segment of the two straight lines equal in length to the line segment, and the target line segment includes the coordinates of the origin to obtain two target line segments;

According to the distance between the origin mark and other mark points, other coordinate points with the same distance from the origin coordinate in the target line segment are determined, and finally multiple coordinate points corresponding to the multiple mark points are obtained.

Optionally, according to the distance between the origin mark and other mark points, other coordinate points in the target line segment at the same distance from the origin coordinates are determined, and finally multiple coordinate points corresponding to the multiple mark points are obtained, Also includes:

Set the origin coordinates of the obtained multiple coordinate points as b, the coordinate point with the larger distance from b in the longer line segment as a, and the coordinate point with the smaller distance from b in the longer line segment as c. Set the coordinate point with the larger distance from b in the short line segment to e, and set the coordinate point with the smaller distance from b in the shorter line segment to d;

Determine whether the distance between a and b and the distance ratio between b and c are greater than the preset ratio threshold, and judge whether the distance between b and d and the distance ratio between d and e are within the preset ratio range , If the ratio of the distance between a and b and the distance between b and c is greater than the ratio threshold, and the distance between b and d and the distance between d and e are within the ratio range, then more Each of the coordinate points is valid coordinate data.

Further, in order to achieve the above objective, the present invention also provides a calibration rod detection device in an optical motion capture system, including:

The coordinate data acquisition module is used to acquire multiple frames of coordinate data captured by the optical camera on the swinging calibration rod, and each frame of the coordinate data includes multiple coordinate point information;

The screening coordinate data module is used for judging whether there are two intersecting straight lines with a common coordinate point formed by a preset number of coordinate points among the plurality of coordinate points in each frame in the multi-frame coordinate data. , Then remove a frame corresponding to the coordinate data, and if it exists, record multiple coordinate points on two intersecting straight lines as qualified coordinate data to obtain qualified multi-frame coordinate data;

The valid data determining module is used to obtain the positional relationship data of multiple marking points on the calibration rod, and according to the positional relationship data, it is determined that each frame of the qualified coordinate data corresponds to the multiple marking points of the calibration rod The multiple coordinate points of the position are recorded as one frame of valid coordinate data, and multiple frames of valid coordinate data are obtained.

To achieve the above objective, the present invention also provides a calibration rod detection device in an optical motion capture system. The device includes a memory, a processor, and an optical motion capture device that is stored in the memory and can run on the processor. The calibration rod detection program in the system implements the steps of the calibration rod detection method in the optical motion capture system when the calibration rod detection program in the optical motion capture system is executed by the processor.

In order to achieve the above object, the present invention also provides a computer-readable storage medium. The computer-readable storage medium stores a calibration rod detection program in an optical motion capture system, and the calibration rod detection program in the optical motion capture system is processed. When the device is executed, the steps of the calibration rod detection method in the optical motion capture system as described above are realized.

The calibration rod detection method in the optical motion capture system provided by the present invention is used in an optical motion capture system based on a two-dimensional calibration rod. The optical camera captures the calibration rod of a fixed shape to obtain a large number of coordinate data. Valid data in the coordinate data. The invention can not only judge whether the coordinate data obtained by the optical camera contains calibration rod information, but also accurately obtain the coordinate data of multiple coordinate points corresponding to the calibration rod coordinate system, which provides indispensable for camera calibration. Information also played a key role in the step of marking the center point in space, laying a solid foundation for the high-precision positioning and tracking of the entire optical motion capture system.

Description of the drawings

By reading the detailed description of the preferred embodiments below, various other advantages and benefits will become clear to those of ordinary skill in the art. The drawings are only used for the purpose of illustrating the preferred embodiments, and are not considered as a limitation to the present invention.

FIG. 1 is a schematic structural diagram of the operating environment of the calibration rod detection device in the optical motion capture system involved in the embodiment of the present invention;

2 is a flowchart of a calibration rod detection method in an optical motion capture system in an embodiment of the present invention;

Fig. 3 is a schematic diagram of a structure of a calibration rod in an embodiment of the present invention;

Fig. 4 is a structural diagram of a calibration rod detection device in an optical motion capture system in an embodiment of the present invention.

Detailed ways

In order to make the objectives, technical solutions, and advantages of the present invention clearer, the following further describes the present invention in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, but not used to limit the present invention.

Those skilled in the art can understand that, unless specifically stated, the singular forms "a", "an", "said" and "the" used herein may also include plural forms. It should be further understood that the term "comprising" used in the specification of the present invention refers to the presence of the described features, integers, steps, operations, elements and/or components, but does not exclude the presence or addition of one or more other features, Integers, steps, operations, elements, components, and/or groups of them.

1, which is a schematic structural diagram of the operating environment of the calibration rod detection equipment in the optical motion capture system involved in the embodiment of the present invention.

As shown in FIG. 1, the calibration rod detection device in the optical motion capture system includes: a processor 1001, such as a CPU, a communication bus 1002, a user interface 1003, a network interface 1004, and a memory 1005. Among them, the communication bus 1002 is used to implement connection and communication between these components. The user interface 1003 may include a display screen (Display) and an input unit such as a keyboard (Keyboard), and the network interface 1004 may optionally include a standard wired interface and a wireless interface (such as a WI-FI interface). The memory 1005 may be a high-speed RAM memory, or a non-volatile memory (non-volatile memory), such as a magnetic disk memory. Optionally, the memory 1005 may also be a storage device independent of the aforementioned processor 1001.

Those skilled in the art can understand that the hardware structure of the calibration rod detection device in the optical motion capture system shown in FIG. 1 does not constitute a limitation on the calibration rod detection device in the optical motion capture system, and may include more or more than that shown in the figure. Few parts, or a combination of some parts, or a different arrangement of parts.

As shown in FIG. 1, the memory 1005, which is a computer-readable storage medium, may include an operating system, a network communication module, a user interface module, and a calibration rod detection program in an optical motion capture system. Among them, the operating system is a program that manages and controls the calibration rod detection equipment and software resources in the optical motion capture system, and supports the operation of the calibration rod detection program and other software and/or programs in the optical motion capture system.

In the hardware structure of the calibration rod detection device in the optical motion capture system shown in Figure 1, the network interface 1004 is mainly used to access the network; the user interface 1003 is mainly used to detect confirmation commands and edit commands, and the processor 1001 can It is used to call the calibration rod detection program in the optical motion capture system stored in the memory 1005, and execute the operations of the following embodiments of the calibration rod detection method in the optical motion capture system.

2 is a flowchart of a calibration rod detection method in an optical motion capture system in an embodiment of the present invention. As shown in FIG. 2, a calibration rod detection method in an optical motion capture system includes the following steps:

Step S1, acquiring coordinate data: acquiring multiple frames of coordinate data captured by the optical camera on the swinging calibration rod, and each frame of coordinate data includes multiple coordinate point information.

The calibration rod in this step adopts a two-dimensional calibration rod. There are a plurality of marking points on the calibration rod, and the marking points are coated with a high-reflective material, which can be recognized by an optical camera. The position relationship of the mark points is preset, and the position relationship data between multiple mark points can be directly obtained. In the process of using, swing the calibration rod in a multi-camera environment in a large space, and the optical camera will recognize the marked points on the calibration rod, obtain each frame of two-dimensional space coordinate data, and record and store these coordinate data.

As shown in Figure 3, the calibration rod 2 includes a horizontal section and a vertical section. There are five marking points 21 on the calibration rod. The horizontal section and the vertical section have a common marking point. The positions of the five marking points 21 are fixed. , Can be set as: the positional relationship of the three mark points on the horizontal segment from left to right is as follows: the distance from the first mark point to the second mark point is 20cm, and the distance from the second mark point to the third mark point The distance is 10cm, and the distance from the first marking point to the third marking point is 30cm; the positional relationship of the three marking points in the vertical section from top to bottom is as follows: the distance from the first marking point to the second marking point is 12cm, the distance from the second marking point to the third marking point is 12cm, and the distance from the first marking point to the third marking point is 24cm. The five marking points 21 on the calibration rod have a fixed height from the ground, and the fixed height can be 5 cm. If the calibration rod coordinate system is established, the common mark point where the horizontal and vertical sections intersect is the origin, the vertical section is the positive direction of the X axis from top to bottom, the vertical upward is the positive direction of the Y axis, and the horizontal section is from right to left. Is the positive direction of the Z-axis, then the coordinates of the five mark points (a, b, c, d, e) are: the three mark points of the horizontal segment from left to right are: the first mark point a(0, 0.05 , 0.20), the second mark point b (0, 0.05, 0), the third mark point c (0, 0.05, -0.1); the three mark points of the vertical section from top to bottom are: the first mark Point b (0, 0.05, 0), the second marking point d (0.12, 0.05, 0), and the third marking point e (0.24, 0.05, 0).

After the calibration rod of the present invention is provided with five marking points 21, during the calibration process of the optical camera, the matching speed is accelerated, the calculation difficulty is reduced, the calibration time is faster, and manpower and material resources are saved. When the center point is detected or when the calibration rod is positioned and tracked, the position of the calibration rod can be determined as long as the correlation of the five points is determined, which greatly reduces the complexity of the algorithm.

Step S2, screening the coordinate data: in the multi-frame coordinate data, determine whether there are two intersecting straight lines with a common coordinate point formed by a preset number of coordinate points among the multiple coordinate points in each frame, if not, then A frame corresponding to the coordinate data is eliminated, and if it exists, multiple coordinate points on the two intersecting straight lines are recorded as qualified coordinate data to obtain qualified multi-frame coordinate data.

Since the calibration bar is constantly swinging during the data collection process in step S1, the coordinate data collected by the optical camera is not complete in every frame of data, that is, it contains the coordinates of multiple marking points on the calibration bar, and even if there are multiple coordinates Point data, it cannot be determined that these multiple coordinates are multiple marked points on the calibration rod. Therefore, this step needs to filter the coordinate data of each frame collected. The preset number in this step is the same as the number of marking points set on the horizontal or vertical section of the calibration rod. If there are five mark points on the calibration rod, the horizontal section is three mark points, and the vertical section is three mark points, the preset number is 3. When there are only two intersecting straight lines among all the coordinate points, multiple data points on the two intersecting straight lines are considered as qualified coordinate data.

In one embodiment, before step S2, it includes pre-screening multiple coordinate points in each frame:

In the multi-frame coordinate data, it is judged whether the number of coordinate points in each frame is within the preset threshold range. If it is not within the threshold range, the frame corresponding to the coordinate data will be eliminated. If it is within the threshold range, the Multiple coordinate points are recorded as qualified coordinate data, and qualified multi-frame coordinate data is obtained.

In the judgment, the threshold range can be 5-500 coordinate points. If the number of coordinate points in a frame is less than 5, it is considered that the current frame does not contain the coordinate data corresponding to the calibration rod, that is, the current frame coordinate data is unqualified. If the number of coordinate points in a frame is more than 500, it is considered that there are too many clutters in the coordinate data of the current frame, excessive useless data, and the coordinate data of the current frame is unqualified. The unqualified coordinate data should be eliminated from the multi-frame coordinate data first. After the elimination, the qualified coordinate data of each frame is obtained, which is used as a follow-up detection, which greatly reduces the complexity of the follow-up algorithm.

In one embodiment, step S2 includes:

S201. Determine whether there is a straight line: in the multi-frame coordinate data, determine whether there is a preset number of coordinate points located on the same straight line among the multiple coordinate points in each frame. If there is no straight line, remove one corresponding to the coordinate data. frame.

When judging whether the preset number of coordinate points are on the same straight line, the following method is used:

S20101, in one frame of coordinate data, choose any three coordinate points, calculate the two-by-two distance between the three coordinate points, and obtain three distance values. The distance between any two coordinate points of the three coordinate points is two The pixel Euclidean distance of the dimensional coordinate is calculated using the following formula:

D=sqrt((x1-x2) ² +(y1-y2) ² )

Among them, D is the distance value, and the two-dimensional coordinates of the two coordinate points are (x1, y1), (x2, y2).

For example, in a frame of coordinate data, any three coordinate points A (x1, y1), B (x2, y2), C (x3, y3) are taken, and the mutual distance between the three points is calculated, then the above calculation The formula obtains the pixel Euclidean distance in two-dimensional coordinates: P=AC, Q=BC, R=AB.

S20102: Find the smallest distance value and the second smallest distance value among the three distance values, and judge whether the second smallest distance value is greater than the preset distance threshold. If the second smallest distance value is greater than the distance threshold, the three coordinate points are not on the same straight line .

Since the positional relationship of the multiple marking points on the calibration rod is determined, there should be coordinate points containing the positional relationship of multiple marking points among the multiple coordinate points in a frame of coordinate data captured by the optical camera. Therefore, this step determines that the three coordinate points are on the same straight line according to the distance between the coordinate points.

For example, among the three distance values P, Q, and R obtained in step S20101, the smallest value is recorded as minU and the second decimal value is recorded as minV. If minV is greater than a preset distance threshold, such as 12, A and B are considered , C three points do not meet the requirements of three points collinear, A, B, C three points are not on the same straight line.

S20103, otherwise, determine whether the ratio of the second smallest distance value to the minimum distance value is greater than the preset ratio threshold, and if the ratio is less than or equal to the ratio threshold, the three coordinate points are not on the same straight line.

When the second smallest distance value is less than or equal to the distance threshold, it is considered that the three coordinate points may be on the same straight line, and the judgment in this step needs to be continued.

For example, when the ratio of minV to minU is less than or equal to the ratio threshold 0.2, it is considered that the three coordinate points are not on the same straight line.

S20104, otherwise, determine whether the included angle between the vector with the second smallest distance value and the vector with the smallest distance value is less than the preset included angle threshold. If the included angle is greater than or equal to the included angle threshold, the three coordinate points are not on the same straight line.

When the ratio of the second smallest distance value to the smallest distance value is greater than the ratio threshold value, it is considered that the three coordinate points may be on the same straight line, and the judgment of this step needs to be continued.

For example, if the angle between the minV and minU vectors is greater than or equal to the angle threshold of 5 degrees, it is considered that the three coordinate points are not on the same straight line.

S20105, otherwise, the three coordinate points are on the same straight line.

Among the three distance values formed by only three coordinate points, the second smallest distance value is less than or equal to the distance threshold, and the ratio of the second smallest distance value to the smallest distance value is greater than the ratio threshold, and the vector of the second smallest distance value and the vector of the smallest distance value When the included angle between is less than the included angle threshold, the three coordinate points meet the requirement of three-point collinear and are located on the same straight line. At this time, the coordinate data of these three coordinate points are saved.

S202: Judging the number of straight lines: if there are straight lines, continue to judge whether the number of straight lines is within a preset number range, and if not, then remove a frame corresponding to the coordinate data.

The number range in this step can be 2-10. If the number of straight lines in a frame of coordinate data is less than 2, it is considered that this frame of coordinate data does not include the calibration rod, that is, this frame of data is unqualified. If the number of straight lines in a frame of coordinate data is greater than 10, it is considered that there are too many noises in the frame of coordinate data and excessive useless data. This frame of data is also unqualified, and the unqualified data should be eliminated.

S203: Determine whether there is a common coordinate point: if it is within the number range, continue to determine whether the coordinate points in the multiple straight lines have a common coordinate point, and if there is no common coordinate point, remove a frame corresponding to the coordinate data.

This step determines whether there are two intersecting straight lines in one frame of coordinate data by judging whether there are common coordinate points. If there are no two intersecting straight lines, it is considered that the calibration rod is not included in the current frame coordinate data, that is, the data of this frame is unqualified, and the unqualified data should be eliminated.

S204: Judging the number of intersecting straight lines: if there are common coordinate points, continue to judge whether there are only two straight lines with common coordinate points, and if there are more than two straight lines, then remove one frame corresponding to the coordinate data.

If the data of the intersecting straight lines in a frame of coordinate data is not 2, that is, whether it is greater than 2 or less than 2, the coordinate data of this frame is considered to be unqualified, and the unqualified data should be eliminated.

S205: Record qualified coordinate data: if there are only two straight lines, record multiple coordinate points on the two intersecting straight lines as qualified coordinate data, and finally obtain qualified multi-frame coordinate data.

If there are and only two intersecting straight lines with a common coordinate point in one frame of coordinate data, the current frame coordinate data is considered to be qualified coordinate data, and all the coordinate points on the two straight lines are saved.

In this embodiment, after multiple levels of judgment, from a large number of multi-frame coordinate data, the multi-frame coordinate data that meets the requirements is organically screened out as qualified coordinate data to provide accurate and reliable data support for the subsequent determination of effective coordinate data. It can also greatly save the amount of calculation in the subsequent determination of effective coordinate data.

Step S3, determine the effective coordinate data: obtain the positional relationship data of the multiple marking points on the calibration rod, and determine the multiple coordinates corresponding to the multiple marking points of the calibration rod in each frame of the qualified coordinate data according to the positional relationship data Point, multiple coordinate points are recorded as one frame of valid coordinate data, and multiple frames of valid coordinate data are obtained.

After step S2, a plurality of qualified coordinate points are screened out for each frame. These coordinate points are distributed on two intersecting straight lines, and the two intersecting straight lines have a common coordinate point. For the needs of the subsequent algorithms of the optical camera, it is necessary to determine the specific relationship or positional relationship of the multiple qualified coordinate points, that is, one-to-one correspondence between the multiple qualified coordinate points and the multiple mark points in the calibration rod coordinate system, and finally determine Effective coordinate data can be generated to provide reliable data for the calibration of the optical camera.

In one embodiment, step S3 includes:

Step S301: Obtain marker point data: acquire positional relationship data of a plurality of marker points on the calibration rod. The positional relationship data includes the length of two intersecting line segments formed by the plurality of marker points, the origin mark, and the coordinates of other marker points corresponding to the origin mark. data.

For example, when the calibration bar of step S1 is used, as shown in Figure 3, the length of the two intersecting line segments is: horizontal section 30cm, vertical section 24cm; the origin mark is: mark point b(0,0.05,0); corresponding to the origin mark The coordinate data of other marker points are: a(0,0.05,0.20), c(0,0.05,-0.1), d(0.12,0.05,0), e(0.24,0.05,0).

Step S302: Determine the origin point coordinates: mark the common coordinate point in the two straight lines formed by multiple coordinate points in a qualified frame of coordinate data as the origin point coordinates, and the origin point coordinates correspond to the origin point mark.

In this step, the common coordinate point is used as the origin of the calibration bar, that is, the origin coordinates correspond to the origin mark. As shown in Fig. 3, the common coordinate point is the mark point b, and the origin coordinates of the current frame are (0, 0.05, 0).

Step S303: Determine two line segments: Calculate the target line segment of the two straight lines equal to the length of the line segment, and the target line segment contains the coordinates of the origin to obtain two target line segments.

According to the shape of the calibration rod, the length of the two line segments on the calibration rod should be different, the longer line segment is the horizontal segment, and the shorter line segment is the vertical segment. Therefore, through this information, two target line segments in two intersecting straight lines can be determined, and each target line segment should contain the origin coordinates.

Step S304: Determine coordinate data: According to the distance between the origin mark and other mark points, other coordinate points in the target line segment with the same distance from the origin coordinates are determined, and finally multiple coordinate points corresponding to the multiple mark points are obtained.

Since the distance between the origin mark in the calibration bar and other mark points can be directly obtained through the mark point coordinates, the distance between the origin mark and other mark points is determined, and the origin mark corresponds to the origin coordinates in the current frame coordinate data, so Multiple other coordinate points corresponding to the marked points can be directly obtained.

For example, after the origin coordinate b is determined, in the horizontal segment, the one with a larger distance from the origin coordinate b, such as 20 cm, is coordinate data a, and the one with a smaller distance from the origin coordinate b, such as 10 cm, is the coordinate data c. In the vertical section, if the distance from the origin coordinate b is larger, such as 24cm, it is the coordinate data e, and the distance from the origin coordinate b is smaller, such as 12cm is the coordinate data d, so as to obtain multiple mark points with the calibration rod. Multiple coordinate data in one-to-one correspondence.

After determining multiple coordinate point information, this step also includes:

Set the origin coordinates of the obtained multiple coordinate points as b, the coordinate point with the larger distance from b in the longer line segment as a, and the coordinate point with the smaller distance from b in the longer line segment as c. Set the coordinate point with the larger distance from b in the short line segment to e, and set the coordinate point with the smaller distance from b in the shorter line segment to d, and judge whether the ratio of the distance between a and b and the distance between b and c is greater than the preset value. Set the ratio threshold to judge whether the distance between b and d and the distance ratio between d and e are within the preset ratio range, if the distance between a and b and the distance between b and c are greater than the ratio Threshold, and the ratio of the distance between b and d and the distance between d and e is within the ratio range, then multiple coordinate points are valid coordinate data.

By judging whether the ratio of the distance between a and b and the distance between b and c is greater than a preset ratio threshold, such as 1.7, whether the distance between b and d and the distance between d and e are within the ratio range , Such as 0.8-1.2, to further determine whether the coordinate data is qualified coordinate data, and the unqualified coordinate data should be eliminated.

In this embodiment, through the combination of the above-mentioned multiple calculation and judgment methods, the coordinate data corresponding to the marked points of the calibration rod can be accurately determined.

The calibration rod detection method in the optical motion capture system of this embodiment filters and calculates a large number of coordinate data captured by the optical camera to determine multiple valid coordinate data corresponding to the calibration rod, which can not only determine whether the camera data contains Calibration rod information, and the coordinate data of multiple coordinate points corresponding to the calibration rod coordinate system can be accurately obtained, which provides indispensable information for camera calibration, and also plays a key role in the step of space marking the center point. , Laid a solid foundation for the high-precision positioning and tracking of the entire optical motion capture system.

In one embodiment, a calibration rod detection device in an optical motion capture system is proposed. As shown in FIG. 4, the device includes:

The coordinate data acquisition module is used to acquire multiple frames of coordinate data captured by the optical camera on the swinging calibration rod, and each frame of coordinate data contains multiple coordinate point information;

The screening coordinate data module is used to determine whether there are two intersecting straight lines with a common coordinate point formed by a preset number of coordinate points among the multiple coordinate points in each frame in the multi-frame coordinate data. If it does not exist, then Eliminate one frame corresponding to the coordinate data, and if it exists, record multiple coordinate points on the two intersecting straight lines as qualified coordinate data to obtain qualified multi-frame coordinate data;

Determine the effective data module, used to obtain the positional relationship data of multiple marking points on the calibration rod, and determine the multiple coordinate points corresponding to the multiple marking points of the calibration rod in each frame of the qualified coordinate data according to the positional relationship data , Multiple coordinate points are recorded as one frame of valid coordinate data, and multiple frames of valid coordinate data are obtained.

In one embodiment, a calibration rod detection device in an optical motion capture system is proposed. The device includes a memory, a processor, and a calibration rod detection program in the optical motion capture system that is stored in the memory and can be run on the processor, When the calibration rod detection program in the optical motion capture system is executed by the processor, the steps in the calibration rod detection method in the optical motion capture system of the foregoing embodiments are implemented.

In one embodiment, a computer-readable storage medium stores a calibration rod detection program in an optical motion capture system. The calibration rod detection program in the optical motion capture system implements the above implementations when executed by a processor. Example of the steps in the calibration rod detection method in the optical motion capture system. Among them, the storage medium may be a volatile storage medium, and the storage medium may also be a non-volatile storage medium.

Those of ordinary skill in the art can understand that all or part of the steps in the various methods of the above-mentioned embodiments can be completed by a program instructing relevant hardware. The program can be stored in a computer-readable storage medium, and the storage medium can include: Read only memory (ROM, Read Only Memory), random access memory (RAM, Random Access Memory), magnetic disk or optical disk, etc.

The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, all possible combinations of the various technical features in the above-mentioned embodiments are not described. However, as long as there is no contradiction in the combination of these technical features, All should be considered as the scope of this specification.

The above-mentioned embodiments only express some exemplary embodiments of the present invention, and the description is relatively specific and detailed, but it should not be understood as a limitation to the patent scope of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can be made, and these all fall within the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention should be subject to the appended claims.

Claims

A method for detecting a calibration rod in an optical motion capture system is characterized in that the method includes the following steps:

Acquiring multiple frames of coordinate data captured by the optical camera on the swinging calibration rod, and each frame of the coordinate data includes multiple coordinate point information;

In the multi-frame coordinate data, determine whether there are two intersecting straight lines with a common coordinate point formed by a preset number of coordinate points in the plurality of coordinate points in each frame, and if not, remove the coordinate data If the corresponding frame exists, multiple coordinate points on the two intersecting straight lines are recorded as qualified coordinate data to obtain qualified multi-frame coordinate data;

Obtain the positional relationship data of the plurality of marking points on the calibration rod, and determine, according to the positional relationship data, a plurality of coordinate points corresponding to the positions of the plurality of marking points of the calibration rod in each frame of the qualified coordinate data, The multiple coordinate points are recorded as one frame of valid coordinate data, and multiple frames of valid coordinate data are obtained.
The method for detecting a calibration rod in an optical motion capture system according to claim 1, wherein in the multi-frame coordinate data, it is determined whether there is a preset number of coordinates among the plurality of coordinate points in each frame Two intersecting straight lines with a common coordinate point formed by the points, if it does not exist, remove one frame corresponding to the coordinate data, if it exists, record multiple coordinate points on the two intersecting straight lines to obtain qualified multi-frame coordinates Before the data, include:

In the multi-frame coordinate data, it is determined whether the number of the multiple coordinate points in each frame is within a preset threshold range, and if it is not within the threshold range, then a frame corresponding to the coordinate data is eliminated; Within the threshold range, a plurality of the coordinate points are recorded as qualified coordinate data to obtain qualified multi-frame coordinate data.
The method for detecting a calibration rod in an optical motion capture system according to claim 1, wherein in the multi-frame coordinate data, it is determined whether there is a preset number of coordinates among the plurality of coordinate points in each frame If two intersecting straight lines with a common coordinate point are formed by points, if it does not exist, the frame corresponding to the coordinate data is eliminated; if it exists, multiple coordinate points on the two intersecting straight lines are recorded as qualified coordinate data, Obtain qualified multi-frame coordinate data, including:

In the multi-frame coordinate data, determining whether there is a preset number of coordinate points on the same straight line among the plurality of coordinate points in each frame, and if there is no straight line, then removing a frame corresponding to the coordinate data;

If there are straight lines, continue to determine whether the number of straight lines is within the preset number range, and if not, remove one frame corresponding to the coordinate data;

If it is within the number range, continue to determine whether the coordinate points in the multiple straight lines have a common coordinate point, and if there is no common coordinate point, remove a frame corresponding to the coordinate data;

If there are common coordinate points, continue to determine whether there are only two straight lines with common coordinate points, and if there are more than two straight lines, then remove one frame corresponding to the coordinate data;

If there are only two straight lines, multiple coordinate points on the two intersecting straight lines are recorded as qualified coordinate data, and finally qualified multi-frame coordinate data is obtained.
The calibration rod detection method in an optical motion capture system according to claim 3, wherein, in the multi-frame coordinate data, it is determined whether there is a preset number of coordinates among the plurality of coordinate points in each frame The points are on the same line and include:

In one frame of coordinate data, randomly select three of the coordinate points, calculate the pairwise distance between the three coordinate points, and obtain three distance values;

Find the smallest distance value and the second smallest distance value among the three distance values, and determine whether the second smallest distance value is greater than a preset distance threshold. If the second smallest distance value is greater than the distance threshold, then three The coordinate points are not on the same straight line;

Otherwise, judging whether the ratio of the second smallest distance value to the minimum distance value is greater than a preset ratio threshold, and if the ratio is less than or equal to the ratio threshold, the three coordinate points are not on the same straight line;

Otherwise, determine whether the included angle between the vector of the second smallest distance value and the vector of the smallest distance value is less than a preset included angle threshold, and if the included angle is greater than or equal to the included angle threshold, then three The coordinate points are not on the same straight line;

Otherwise, the three coordinate points are located on the same straight line.
The method for detecting a calibration rod in an optical motion capture system according to claim 4, characterized in that, in one frame of coordinate data, any three coordinate points are selected, and the two coordinate points between the three coordinate points are calculated. Distance, get three distance values, including:

The distance between any two of the three coordinate points is the pixel Euclidean distance of two-dimensional coordinates, and is calculated using the following formula:

D=sqrt((x1-x2) 2 +(y1-y2) 2 )

Wherein, D is the distance value, and the two-dimensional coordinates of the two coordinate points are (x1, y1) and (x2, y2).
The method for detecting a calibration rod in an optical motion capture system according to claim 1, wherein the position relationship data of a plurality of marking points on the calibration rod is acquired, and the qualified ones are determined according to the position relationship data. In one frame of coordinate data, multiple coordinate points corresponding to multiple mark points of the calibration rod are recorded as one frame of valid coordinate data, and multiple frames of valid coordinate data are obtained, including:

Acquiring positional relationship data of a plurality of marking points on the calibration rod, the positional relationship data including the length of two intersecting line segments formed by the plurality of marking points, an origin mark, and other marking point coordinate data corresponding to the origin mark;

Mark a common coordinate point in two straight lines formed by a plurality of coordinate points in a qualified frame of coordinate data as an origin coordinate, and the origin coordinate corresponds to the origin mark;

Calculate a target line segment of the two straight lines equal in length to the line segment, and the target line segment includes the coordinates of the origin to obtain two target line segments;

According to the distance between the origin mark and other mark points, other coordinate points with the same distance from the origin coordinate in the target line segment are determined, and finally multiple coordinate points corresponding to the multiple mark points are obtained.
The method for detecting a calibration rod in an optical motion capture system according to claim 6, wherein the other coordinates in the target line segment that are the same distance from the origin coordinates are determined based on the distance between the origin mark and other mark points Point, after finally obtaining multiple coordinate points corresponding to multiple marked points, it also includes:

Set the origin coordinates of the obtained multiple coordinate points as b, the coordinate point with the larger distance from b in the longer line segment as a, and the coordinate point with the smaller distance from b in the longer line segment as c. Set the coordinate point with the larger distance from b in the short line segment to e, and set the coordinate point with the smaller distance from b in the shorter line segment to d;

Determine whether the distance between a and b and the distance ratio between b and c are greater than the preset ratio threshold, and judge whether the distance between b and d and the distance ratio between d and e are within the preset ratio range , If the ratio of the distance between a and b and the distance between b and c is greater than the ratio threshold, and the distance between b and d and the distance between d and e are within the ratio range, then more Each of the coordinate points is valid coordinate data.
A calibration rod detection device in an optical motion capture system, characterized in that the device comprises:

The coordinate data acquisition module is used to acquire multiple frames of coordinate data captured by the optical camera on the swinging calibration rod, and each frame of the coordinate data includes multiple coordinate point information;

The screening coordinate data module is used for judging whether there are two intersecting straight lines with a common coordinate point formed by a preset number of coordinate points among the plurality of coordinate points in each frame in the multi-frame coordinate data. , Then remove a frame corresponding to the coordinate data, and if it exists, record multiple coordinate points on two intersecting straight lines as qualified coordinate data to obtain qualified multi-frame coordinate data;

The valid data determining module is used to obtain the positional relationship data of multiple marking points on the calibration rod, and according to the positional relationship data, it is determined that each frame of the qualified coordinate data corresponds to the multiple marking points of the calibration rod The multiple coordinate points of the position are recorded as one frame of valid coordinate data, and multiple frames of valid coordinate data are obtained.
A calibration rod detection device in an optical motion capture system, characterized in that the device includes:

A memory, a processor, and a calibration rod detection program in an optical motion capture system that is stored on the memory and can run on the processor, and the calibration rod detection program in the optical motion capture system is implemented when the processor is executed The steps of the calibration rod detection method in the optical motion capture system according to any one of claims 1 to 7.
A computer-readable storage medium, characterized in that a calibration rod detection program in an optical motion capture system is stored on the computer-readable storage medium, and the calibration rod detection program in the optical motion capture system is executed by a processor. The steps of the calibration rod detection method in the optical motion capture system according to any one of claims 1 to 7.