JP2004361222A - System and method for measuring three-dimensional position - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To use measurement information of other luminescent markers effectively by specifying a marker by causing a measuring error, in a three-dimensional position measuring system. <P>SOLUTION: This three-dimensional position measuring system 2 is provided with luminescent markers 4a, 4b attached to a measuring object, a first and second moving image cameras 6A, 6B for imaging the luminescent markers, and a measuring instrument 8. In the measuring instrument, plane coordinates of the respective luminescent markers within the first and second images imaged respectively by the first and second moving image cameras are calculated, and then spatial coordinates of the markers are calculated according to a principle of stero-view. A distance between the luminescent markers is calculated thereafter based on the spatial coordinates to determine the propriety of the intermarker distance. When the intermarker distance is determined to be not proper, a marker moving distance from a front side by one frame of the camera image is calculated, and the marker having the marker moving distance larger than a predetermined threshold is determined to cause the measuring error. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates generally to a three-dimensional position measurement system and method, and more particularly to a system and method for measuring a three-dimensional position of a plurality of luminescent markers attached to a plurality of sites to be measured, such as a person.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, there has been known a three-dimensional measurement system in which markers are attached to a plurality of portions of a measurement target such as a person, and three-dimensional positions of the markers are measured to analyze the operation of the target. Such a three-dimensional position measurement system generally captures a marker with a plurality of moving image cameras and calculates the three-dimensional position of the marker using the principle of stereo vision.
[0003]
When measurement is performed by such a three-dimensional position measurement system, various kinds of noise, changes in the light environment (for example, direct light or reflected light is mixed in the field of view of the camera due to the sun, etc.) are caused. There is a possibility that a measurement error (for example, light in an image generated due to a change in light environment is erroneously recognized as a marker).
[0004]
Therefore, for example, in a motion analysis device (three-dimensional position measurement system) disclosed in Patent Document 1, a distance between markers is calculated at the same time as measuring a marker position, and the calculated distance is compared with a predetermined reference distance. If the calculated distance is appropriate, the calculated marker three-dimensional position is determined as an appropriate three-dimensional position.
[0005]
[Patent Document 1]
JP-A-2002-8043
[0006]
[Problems to be solved by the invention]
However, in the above-described motion analysis device, if the distance between the markers is determined to be inappropriate, the subsequent measurement is set to be stopped, so that stable position measurement cannot be performed. In addition, even when it is determined that the distance between the markers is inappropriate, the correct position information is not effectively used although the position information of one marker is likely to be correct.
[0007]
Therefore, the present invention is a three-dimensional measurement system and method for determining a measurement error using marker distance information, which can effectively use correct position information when the marker distance is determined to be inappropriate. Is provided.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the three-dimensional position measurement system according to the present invention,
A plurality of light-emitting markers attached to the measurement target,
First and second moving image cameras for imaging the plurality of light emitting markers,
A two-dimensional position calculation unit that calculates planar coordinates of each of the light emitting markers in the first and second images captured by the first and second moving image cameras, respectively;
Based on the planar coordinates of each of the luminescent markers in the first and second images calculated by the two-dimensional position calculator, the spatial coordinates (first spatial coordinates) of each of the luminescent markers are calculated based on the principle of stereo vision. A stereo vision calculation unit that performs
A marker distance calculating unit that calculates a distance between the light emitting markers based on the spatial coordinates calculated by the stereo visual calculation unit;
A measurement error determination unit that determines whether the marker distance calculated by the marker distance calculation unit is appropriate,
For each of the light-emitting markers constituting the light-emitting marker pair for which the distance between the markers has been determined to be inappropriate by the measurement error determination unit, the corresponding first and second images and the first and second images immediately before being determined to be incorrect. A marker moving distance calculation unit that calculates a marker moving distance based on the two images;
A measurement error marker determining unit that determines a light emitting marker that has caused the determination that the distance between the markers is incorrect based on the marker moving distance.
[0009]
The three-dimensional position measuring method according to the present invention,
Imaging the plurality of light-emitting markers attached to the measurement target with the first and second moving image cameras;
Calculating the plane coordinates of each of the light emitting markers in the first and second images captured by the first and second moving image cameras, respectively;
Calculating spatial coordinates (first spatial coordinates) of each of the light-emitting markers based on the stereoscopic principle based on the calculated two-dimensional position of each of the light-emitting markers in each image;
Calculating a distance between the respective light-emitting markers based on spatial coordinates;
A measurement error determination step of determining whether the calculated distance between markers is appropriate,
When it is determined that the distance between the markers calculated in the measurement error determination step is inappropriate, one of the light-emitting markers constituting the light-emitting marker pair corresponding to the distance between the markers is determined to be an inappropriate distance between the markers. Determining whether the determination has been caused.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
[0011]
Embodiment 1 FIG.
1 and 2 are schematic configuration diagrams showing a first embodiment of a three-dimensional position measurement system (hereinafter, referred to as a measurement system) according to the present invention. The measurement system 2 generally includes a pair of light-emitting markers 4 (4a, 4b) (LEDs in the present embodiment) mounted on a predetermined portion of a measurement target (for example, a person) moving (moving) within a predetermined range, First and second moving image cameras (CCD cameras in the present embodiment, hereinafter referred to as cameras) 6 (6A, 6B) for capturing the range in which the measurement target moves in the field of view, and the first and second cameras Based on the time-series image data picked up by 6A and 6B, the three-dimensional positions of the light emitting markers 4a and 4b are set at appropriate time intervals (this interval is an integral multiple of the period of the vertical drive (VD) signal of the CCD as the image pickup means). And a measuring device 8 for performing the measurement.
[0012]
The measuring device 8 controls a control unit 10 that controls the entire measuring system 2, an image memory 12 for storing first and second time-series image data captured by the cameras 6A and 6B, and controls light emission of the LEDs 4a and 4b. A light / emission control unit 14, a camera / marker information management unit 16 for managing information such as predetermined positions and orientations of the cameras 6A and 6B, and a distance between the light emission markers 4a and 4b, and a light emission marker 4a and 4b. A three-dimensional position calculator 18 for calculating a three-dimensional position at each time, a three-dimensional position recorder 20 for recording the three-dimensional position calculated by the calculator 18 and the like are provided.
[0013]
As shown in FIG. 2, the three-dimensional position calculation unit 18 includes a local position calculation unit (two-dimensional position calculation unit) 22, a stereo visual calculation unit 24, a marker distance calculation unit 26, a measurement error determination unit 28, a marker movement distance. A calculation unit 30, a measurement error marker determination unit 32, and a three-dimensional position output unit 34 are provided.
[0014]
The local position calculation unit 22 determines the local positions (planar coordinates) of the light emitting markers 4a and 4b in each image frame forming the first time-series image data and in each image frame forming the second time-series image data. Is calculated. For example, regarding a certain image frame, a pixel portion whose luminance exceeds a predetermined threshold value for each horizontal scanning line is cut out as a marker existing portion (line segment). Then, if there is a marker existing portion at substantially the same position in the horizontal direction in the adjacent horizontal scanning lines, it is determined that the marker is the same, so that the number of horizontal drive (HD) signals in the horizontal direction and the horizontal scanning line in the vertical direction are determined. The plane coordinates of the light emitting markers 4a and 4b can be obtained based on the numbers. For example, the coordinates of the center of gravity of the light emitting markers 4a and 4b are obtained, and these are set as local positions of the light emitting markers 4a and 4b.
[0015]
The stereo vision calculation unit 24 emits light based on the plane coordinates calculated by the local position calculation unit 22 and data such as the position and orientation of the camera managed by the camera / marker information management unit 16 using the principle of stereo vision. The three-dimensional positions (first spatial coordinates) of the markers 4a and 4b are obtained. The marker distance calculation unit 26 calculates the distance D between the markers from the first spatial coordinates of each of the light-emitting markers 4a and 4b calculated by the stereo vision calculation unit 24. ₁ Is calculated. The measurement error determination unit 28 calculates the distance D between the light emitting markers 4a and 4b calculated by the marker distance calculation unit 26. ₁ And a distance D between the known light emitting markers 4a and 4b managed by the camera / marker information management unit 16. ₀ And the absolute value of the difference between the distances | D ₁ -D ₀ Is larger than a predetermined threshold value. If the absolute value is larger than the threshold value, it is determined that the first spatial coordinate of at least one of the light emitting markers 4a and 4b is a measurement error, and An error signal is output to the moving distance calculation unit 30.
[0016]
When receiving the error signal from the measurement error determination unit 28, the marker moving distance calculation unit 30 calculates the three-dimensional position (second position) calculated using the image frame “just before” (for example, one cycle or two cycles before the VD signal). The spatial distance of each of the light emitting markers 4a and 4b is calculated from the first spatial coordinates calculated using the image frame to be subjected to the three-dimensional position calculation. The data of the second spatial coordinates is appropriately read from the three-dimensional position recording unit 20, but instead, the three-dimensional position calculating unit 18 is separately provided with a memory for temporarily storing the data of the second spatial coordinates. You may. The measurement error marker determination unit 32 determines whether the moving distance of each of the light emitting markers 4a and 4b is larger than a preset threshold. That is, with respect to a certain light emitting marker 4, the distance that moves during one or two cycles (one cycle is, for example, 1/60 second) is a threshold (the distance at which the part to which the light emitting markers 4a and 4b are mounted can move in one or two cycles) If the value is equal to or more than (the limit value of an appropriate value) (the moving speed is high), it is highly likely that the first spatial coordinates are calculated by erroneously recognizing light other than the light emitting marker 4 as the light emitting marker.
[0017]
Although the details will be described later, the three-dimensional position output unit 34 determines the three-dimensional position information of each of the markers 4 a and 4 b to be output to the three-dimensional position recording unit 20 based on the determination by the measurement error marker determination unit 32. It has become.
[0018]
Next, three-dimensional measurement processing by the measurement system 2 according to the present embodiment will be described with reference to the flowcharts of FIGS.
[0019]
First, in step S301, the control unit 10 controls the light emission control unit 14 to cause the LEDs 4a and 4b to emit light. In step S302, the measurement object is imaged by the first and second cameras 6A and 6B, and first and second time-series image data arranged in time series are acquired and stored in the image memory 12. In step S303, the index n is set to 0. The index n corresponds to the number of times of measuring the three-dimensional position of each of the light emitting markers 4a and 4b. In step S304, an image frame at the time of initial imaging is selected from the first and second time-series image data captured by the first and second cameras 6A and 6B, respectively. Then, the local position calculator 22 of the three-dimensional position calculator 18 calculates the plane coordinates of the light emitting markers 4a and 4b on each image frame. In step S305, the stereo vision calculation unit 24 calculates the first spatial coordinates of each of the light emitting markers 4a, 4b from the plane coordinates of each of the light emitting markers 4a, 4b according to the principle of stereo vision. In step S306, the marker distance calculating unit 26 calculates the distance D between the light emitting markers 4a and 4b. ₁ Is calculated. In step S307, the measurement error determination unit 28 determines the distance D ₁ And the actual distance D between the light emitting markers 4a and 4b stored in the camera / marker information management unit 16. ₀ Is calculated.
[0020]
In step S308, the absolute value of the difference | D ₁ -D ₀ If | is smaller than the predetermined threshold, the process proceeds to step S309, where the measurement error determination unit 28 determines that the first spatial coordinates of each of the light emitting markers 4a and 4b calculated in step S305 are appropriate, and outputs the three-dimensional position. An appropriate signal is output to the unit 34. The three-dimensional position output unit 34 outputs and records the data of the first spatial coordinates to the three-dimensional position recording unit 20. Thereafter, the flow proceeds to step S310.
[0021]
In step S310, the index n is incremented. In step S311, if the index n is smaller than N (this is equal to the total number of measurements of each of the light emitting markers 4a and 4b), the flow returns to step S304, and the process of steps S304 to S310 is performed for the next oldest measurement time. repeat. If n becomes equal to N in step S311, the flow ends.
[0022]
In step S308, the absolute value | D ₁ -D ₀ If | is equal to or greater than the predetermined threshold, the flow proceeds to step S312. In the flow after step S312, it is determined whether any of the first spatial coordinates of the light-emitting markers 4a and 4b is inappropriate (although the possibility is low, it is inappropriate for both the light-emitting markers 4a and 4b). It can also be determined that a three-dimensional position is calculated.) Specifically, the index r is set to 0 in step S312. r corresponds to the number of light-emitting markers 4. In step S313, for one of the light-emitting markers 4a and 4b, for example, the light-emitting marker 4a, the marker moving distance calculation unit 30 determines the distance D that the light-emitting marker 4a has moved between the immediately preceding time and the target time. ₂ Is calculated.
[0023]
In step S314, the moving distance D ₂ If is smaller than the preset threshold value, the process proceeds to step S315, where the measurement error marker determining unit 32 determines that the first spatial coordinates of the light emitting marker 4a obtained in step S305 are appropriate, and outputs the three-dimensional position output unit. An appropriate signal is output to 34. The three-dimensional position output unit 34 outputs and records the data of the first spatial coordinates to the three-dimensional position recording unit 20. The flow then proceeds to step S316.
[0024]
In step S314, the moving distance D ₂ Is greater than or equal to the preset threshold, the process proceeds to step S317, where the measurement error marker determination unit 32 determines that the first spatial coordinates of the light emitting marker 4a obtained in step S305 are inappropriate, and determines the three-dimensional position. An error signal is output to the output unit 34. Then, the three-dimensional position output unit 34 outputs, to the three-dimensional position recording unit 20, the data of the second spatial coordinates obtained based on the immediately preceding image frame (instead of the first spatial coordinates), and records the data. As described above, by determining the marker moving distance by using the three-dimensional position immediately before the time series, it is possible to identify the luminescent marker causing the measurement error, and as a result, the effective measurement data regarding the other luminescent marker is obtained. Can be used to the maximum, and stable marker position measurement can be performed. The flow then proceeds to step S316.
[0025]
In step S316, the index r is incremented. If the index r is smaller than 2 in step S318, the process returns to step S313, and the processes of steps S313 to S317 are repeated for the remaining light emitting markers 4b. When r becomes equal to 2 in step S317, the process returns to step S310.
[0026]
As a method of identifying the light-emitting markers 4a and 4b, for example, a method of controlling the light-emitting control unit 14 to alternately light the light-emitting markers 4a and 4b in synchronization with the VD signal, or a method of detecting the image frame at the time of the measurement target For example, a method in which an image frame in which the position of the light emitting marker is close in the immediately preceding image frame is set to be the same marker can be exemplified.
[0027]
The number of moving image cameras may be three or more. In this case, the stereo vision calculation unit 24 calculates the first spatial coordinates for each of a pair of cameras capturing the light-emitting markers 4a and 4b based on the principle of stereo vision, and then calculates the plurality of calculated first spatial coordinates. And the inter-marker distance calculation unit 26 may obtain the inter-marker distance from the averaged first spatial coordinates.
[0028]
The number of luminescent markers may be three or more. In this case, the marker distance calculating unit 26 may calculate a plurality of marker distances, and the measurement error determining unit 28 determines a measurement error for each calculated marker distance.
[0029]
In the present embodiment, the position measurement is performed after the time-series image data is obtained first. However, the position measurement may be performed at the same time as the image data at each measurement time is obtained (that is, in real time). Good.
[0030]
Embodiment 2 FIG.
FIGS. 5 and 6 are schematic configuration diagrams showing Embodiment 3 of the three-dimensional position measurement system according to the present invention. In the following description, components that are the same as or similar to those of the first embodiment are denoted by the same reference numerals or the same reference numerals with appropriate subscripts. The measurement system 2a according to the present embodiment is similar to the measurement system 2 according to the first embodiment, but includes three light-emitting markers 4a, 4b, and 4c, and a three-dimensional position calculation unit 18a. The difference is that the measurement error marker determination unit 32a specifies the light emitting marker that caused the measurement error by using the distance between the markers instead of the marker moving distance.
[0031]
Specifically, with reference to FIGS. 7 and 8 which are flowcharts of the three-dimensional measurement processing by the measurement system 2a according to the present embodiment, first, in step S701, the control unit 10 controls the light emission control unit 14 to control the LED 4a , 4b, 4c. In step S702, the measurement object is imaged by the first and second cameras 6A and 6B, and first and second time-series image data arranged in time series are acquired and stored in the image memory 12. In step S703, the index n is set to 0. In step S704, an initial image frame is selected from the first and second time-series image data captured by the first and second cameras 6A and 6B, respectively. Then, the local position calculator 22 of the three-dimensional position calculator 18 calculates the plane coordinates of the light emitting markers 4a, 4b, 4c on each image frame. In step S705, the stereo vision calculation unit 24 calculates first spatial coordinates from the plane coordinates of each of the light emitting markers 4a, 4b, 4c based on the principle of stereo vision.
[0032]
In step S706, the inter-marker distance calculation unit 26 determines the distance D between the light-emitting markers 4a and 4b for each light-emitting marker pair. ₁ (A, b), distance D between luminescent markers 4b, 4c ₁ (B, c) and the distance D between the light emitting markers 4c, 4a ₁ (C, a) is calculated. In step S707, the measurement error determination unit 28 determines that the distance D ₁ (A, b) and the actual distance D between the light emitting marker pair 4a, 4b ₀ Difference from (a, b), distance D ₁ (B, c) and the actual distance D between the light emitting marker pair 4b, 4c ₀ Difference from (b, c) and distance D ₁ (C, a) and the actual distance D between the light emitting marker pair 4c, 4a ₀ The difference from (c, a) is calculated. Actual distance D ₀ (A, b), D ₀ (B, c), D ₀ (C, a) is stored in the camera / marker information management unit 16.
[0033]
In step S708, the absolute value of the difference | D for all pairs ₁ -D ₀ If | is smaller than the predetermined threshold value, the process proceeds to step S709, and the measurement error determination unit 28 determines that the first spatial coordinates of each of the light-emitting markers 4a, 4b, and 4c calculated in step S705 are appropriate. An appropriate signal is output to the position output unit 34. The three-dimensional position output unit 34 outputs and records the data of the first spatial coordinates to the three-dimensional position recording unit 20. Thereafter, the flow proceeds to step S710.
[0034]
In step S710, the index n is incremented. In step S711, if the index n is smaller than N, which is the total number of times of measurement of each of the light emitting markers 4a, 4b, 4c, the flow returns to step S704, and the processes of steps S704 to S710 are repeated for the next oldest measurement time. If n is equal to N in step S711, the flow ends.
[0035]
In step S708, the absolute value | D ₁ -D ₀ If there is one marker pair where | is equal to or greater than the predetermined threshold, the flow proceeds to step S712. In the following description, it is assumed that the light emitting marker pair 4a, 4b is an error marker pair.
[0036]
In step S712, the index r is set to 0. For one of the light-emitting markers 4a and 4b, for example, the light-emitting marker 4a, the measurement error marker determining unit 32a determines the absolute value of the distance difference between the light-emitting marker 4a and the light-emitting marker 4c other than the light-emitting marker 4b. ｜ D ₁ (C, a) -D ₀ It is checked whether (c, a) | is smaller than a preset threshold (steps S713 and S714). If the difference is smaller than the threshold value, the process proceeds to step S715, where the measurement error marker determination unit 32a determines that the first spatial coordinates obtained in step S705 for the light-emitting marker 4a are appropriate, and the three-dimensional position output unit 34 determines Output a signal. The three-dimensional position output unit 34 outputs and records the data of the first spatial coordinates to the three-dimensional position recording unit 20. The flow then proceeds to step S716.
[0037]
In steps S713 and S714, the absolute value | D ₁ (C, a) -D ₀ If (c, a) | is equal to or larger than the preset threshold value, the process proceeds to step S717, and the measurement error marker determination unit 32 determines that the first spatial coordinates obtained in step S705 for the light emitting marker 4a are inappropriate. Judge, and output an error signal to the three-dimensional position output unit 34. Then, the three-dimensional position output unit 34 outputs and records the data of the second space coordinates obtained based on the immediately preceding image frame (instead of the first space coordinates) to the three-dimensional position recording unit 20. As described above, the measurement error marker can be specified by using the plurality of marker distance information for each marker constituting the error marker pair, and as a result, the effective measurement data for the other luminescent marker can be maximized. The marker can be used, and stable marker position measurement can be performed. The flow then proceeds to step S716.
[0038]
In step S716, the index r is incremented. If the index r is smaller than 2 in step S718, the process returns to step S713, and the processes of steps S713 to S717 are repeated for the remaining light emitting markers 4b. When r becomes equal to 2 in step S718, the process returns to step S710.
[0039]
In the present embodiment, the number of light emitting markers may be four or more. In this case, assuming that the error marker pair is the light-emitting markers 4a and 4b, in steps S713 and S714, for one of the light-emitting markers 4a and 4b, for example, for the light-emitting marker 4a, the measurement error marker determination unit 32a sets the light-emitting marker 4a and The distance difference | D from all the light-emitting markers other than the light-emitting marker 4b (for example, three when using five light-emitting markers) ₁ -D ₀ Is checked if | is smaller than a preset threshold. At this time, the measurement error marker determination unit 32a determines whether the first spatial coordinates obtained in step S705 for the light-emitting marker 4a are appropriate, even if there is at least one of the distance differences smaller than the threshold. It may be good, only when all distance differences are smaller than the threshold value, or in the middle.
[0040]
Embodiment 3 FIG.
9 and 10 are schematic configuration diagrams showing Embodiment 3 of the three-dimensional position measurement system according to the present invention. The measurement system 2b according to the present embodiment does not perform position measurement after acquiring time-series image data, but performs position measurement at the same time as acquiring image data at each measurement time. When the measurement error marker determination unit 32b of the three-dimensional position calculation unit 18b determines that the measurement error has occurred, the measurement error marker pair is again measured by the stereoscopic method, and then the three-dimensional position output unit 34 outputs The original position is recorded.
[0041]
Specifically, with reference to FIGS. 11 and 12 which are flowcharts of the three-dimensional measurement processing by the measurement system 2b according to the present embodiment, first, in step S1101, the control unit 10 controls the light emission control unit 14 to control the LED 4a. , 4b emit light. In step S1103, the index n is set to 0. In step S1103, the measurement target is imaged by the first and second cameras 6A and 6B, and the image frame at the first measurement time is stored in the image memory 12. In step S1104, with respect to the image frame at the first measurement time, the local position calculator 22 of the three-dimensional position calculator 18 calculates the plane coordinates of the light emitting markers 4a and 4b on each image frame. In step S1105, the stereo vision calculation unit 24 calculates the first spatial coordinates from the plane coordinates of the light emitting markers 4a and 4b based on the principle of stereo vision. In step S1106, the marker distance calculating unit 26 calculates the distance D between the light emitting markers 4a and 4b. ₁ Is calculated. In step S1107, the measurement error determination unit 28 determines the distance D ₁ And the actual distance D between the light emitting markers 4a and 4b ₀ Is calculated.
[0042]
In step S1108, the absolute value of the difference | D ₁ -D ₀ If | is smaller than the predetermined threshold value, the process proceeds to step S1109, where the measurement error determination unit 28 determines that the first spatial coordinates of each of the light emitting markers 4a and 4b calculated in step S1105 are appropriate, and outputs the three-dimensional position. An appropriate signal is output to the unit 34. The three-dimensional position output unit 34 outputs and records the data of the first spatial coordinates to the three-dimensional position recording unit 20. Thereafter, the flow proceeds to step S1110.
[0043]
In step S1110, the index n is incremented. If it is determined in step S1111 that the index n is smaller than N, the flow returns to step S1103, and the processes in steps S1104 to S1110 are performed for the image frame at the next measurement time. If n is equal to N in step S1111 (that is, the measurement of the three-dimensional positions of the light emitting markers 3a and 3b is completed for the N image frames), the flow ends.
[0044]
In step S1108, the absolute value | D ₁ -D ₀ If | is equal to or greater than the predetermined threshold, the flow proceeds to step S1112. In the flow after step S1112, the three-dimensional positions of the light emitting markers 4a and 4b are measured again. Specifically, the index r is set to 0 in step S1112. In step S1113, the light emission control unit 14 is controlled so that one of the light emission markers 4a and 4b, for example, the light emission marker 4a emits light for one cycle in synchronization with the VD signal. At this time, the light emitting marker 4b does not emit light.
[0045]
In step S1114, image frames are acquired from the first and second cameras 6A and 6B, respectively, and stored in the image memory 12. In step S1115, with respect to the image frames captured by the first and second cameras 6A and 6B, the local position calculator 22 of the three-dimensional position calculator 18 calculates the plane coordinates of the light emitting marker 4a on each image frame. In step S1116, the stereo vision calculation unit 24 re-calculates the first spatial coordinates from the plane coordinates of the light emitting marker 4a by the stereo vision method. Thereafter, the flow proceeds to step S1117.
[0046]
In step S1117, the index r is incremented. If the index r is smaller than 2 in step S1118, the process returns to step S1113, and the processes of steps S1113 to S1117 are repeated for the remaining light emitting markers 4b to calculate the first spatial coordinates of the light emitting markers 4b again. When r becomes equal to 2 in step S1118, the flow proceeds to step S1119.
[0047]
In step S1119, the marker distance calculation unit 26 calculates the distance D between the light emitting markers 4a and 4b from the first spatial coordinates calculated again in step S1116. ₁ 'Is calculated. In step S1120, measurement error determination unit 28 determines this distance D ₁ 'And the actual distance D between the light emitting markers 4a and 4b. ₀ Is calculated.
[0048]
In step S1121, the absolute value of the difference | D ₁ '-D ₀ If | is smaller than the predetermined threshold, the process proceeds to step S1122, where the measurement error determination unit 28 determines that the first spatial coordinates of each of the light emitting markers 4a and 4b calculated again in step S1116 are appropriate, and An appropriate signal is output to the output unit 34. The three-dimensional position output unit 34 outputs and records the data of the first spatial coordinates to the three-dimensional position recording unit 20. Thereafter, the flow returns to step S1110.
[0049]
In step S1121, the absolute value | D ₁ '-D ₀ If | is equal to or greater than the preset threshold value, the process proceeds to step S1123, where the measurement error marker determination unit 32 determines that the first spatial coordinates of the light-emitting marker 4a obtained in step S1116 are also inappropriate, and An error signal is output to the original position output unit 34. Then, the three-dimensional position output unit 34 outputs and records the data of the second space coordinates obtained based on the immediately preceding image frame (the image frame at the measurement time) to the three-dimensional position recording unit 20. Thereafter, the flow returns to step S1110.
[0050]
As described above, when the measured marker distance does not match the actual distance between the markers, the LEDs 4a and 4b are sequentially lit in synchronization with the VD signal, and the three-dimensional positions of the luminescent markers 4a and 4b are re-established. Since measurement is performed, there is no occurrence of a measurement error in the position of the other light-emitting marker due to reflected light generated by light emission of one light-emitting marker, and the effect of marker identification error can be reduced, so that high accuracy can be achieved. Can be measured.
[0051]
In the present embodiment, the synchronous light-emitting process is performed on both the light-emitting markers 4a and 4b constituting the error marker pair. However, only a specific light-emitting marker, for example, only a light-emitting marker that previously caused a measurement error is synchronized. Light emission processing may be performed.
[0052]
Embodiment 4 FIG.
13 and 14 are schematic configuration diagrams showing Embodiment 3 of the three-dimensional position measurement system according to the present invention. The three-dimensional position calculator 18c of the measurement system 2c according to the present embodiment includes a light emitting area calculator 36, a marker-camera distance, instead of the marker moving distance calculator 30 of the three-dimensional position calculator 18 of the first embodiment. A calculation unit 38 and a light emission area calculation unit 40 are provided. The light emitting area calculation unit 36 calculates a light emitting area of a light emitting marker in an image. The marker-camera distance calculating unit 38 calculates the distance between the light emitting area and the distance stored in the camera / marker information managing unit 16 based on the light emitting area calculated by the light emitting area calculating unit 36. The distance between the light emitting marker 4 and the imaging surface of the camera 6 is calculated. The luminous area calculation unit 40 calculates the luminous marker based on the distance calculated by the marker / camera distance calculation unit 38 and the information such as the position and orientation of one camera 6 stored in the camera / marker information management unit 16. Fourth three-dimensional positions (third spatial coordinates) are calculated.
[0053]
Next, three-dimensional measurement processing by the measurement system 2c according to the present embodiment will be described using the flowcharts of FIGS. However, steps S1501 to S1511 are the same as steps S301 to S311 in FIG. 3, and the description will not be repeated unless particularly necessary.
[0054]
In step S1508, the distance D between the light emitting markers 4a and 4b calculated from the first spatial coordinates calculated in step S1505. ₁ And the reference distance D ₀ Absolute value of difference from | D ₁ -D ₀ If | is equal to or greater than the predetermined threshold, the flow proceeds to step S1512.
[0055]
In step S1512, the index q is set to 0. q corresponds to the number of cameras 6. In step S1513, the light emitting area calculation unit 36 calculates the marker light emitting area in each of the light emitting markers 4a and 4b in an image frame captured by one camera, for example, the first camera 6A. In step S1514, the marker-camera distance calculator 38 calculates the distance between each of the light-emitting markers 4a and 4b and the imaging surface of the CCD camera 6A based on the marker light-emitting area calculated in step S1513. In step S1515, the light emitting area calculation unit 40 stores the distance calculated in step S1514, the plane coordinates of the light emitting markers 4a and 4b in the image frame by the camera 6A calculated in step S1504, and the camera / marker information management unit 16. The third spatial coordinates of the light-emitting markers 4a and 4b based on the image frame captured by the first camera 6A are calculated based on the information on the camera position and posture, etc. thus obtained. Thereafter, the flow proceeds to step S1516.
[0056]
In step S1516, the index q is incremented. If the index q is smaller than 2 in step S1517, the process returns to step S1513, and the processes of steps S1513 to S1516 are repeated for the remaining second camera 6B, and the light emitting marker based on the image frame captured by the second camera 6B The third spatial coordinates of 4a and 4b are calculated. When q becomes equal to 2 in step S1517, the process proceeds to step S1518, where the distance between the light emitting markers 4a and 4b corresponding to the first camera 6A and the distance between the light emitting markers 4a and 4b corresponding to the second camera 6B are determined. Is calculated. In step S1519, each distance D calculated in step S1520 ₃ And the actual distance D between the markers ₀ Is calculated.
[0057]
In step S1520, the absolute value of the difference | D ₃ -D ₀ It is determined whether or not there is a camera 6 in which | is smaller than a preset threshold. If such a camera 6 exists, the flow proceeds to step S1521. Then, in the flow after step S1521, the light emitting marker that caused the measurement error is specified, and the third spatial coordinates calculated using the light emitting area for the light emitting marker are output to the three-dimensional position recording unit 20 and recorded.
[0058]
More specifically, the index r is set to 0 in step S1521. In step S1522, with respect to one of the light-emitting markers, for example, the light-emitting marker 4a, a deviation between the first space coordinate based on the stereoscopic principle calculated in step S1505 and the third space coordinate using the light-emitting area calculated in step S1515. Is calculated.
[0059]
If the deviation is smaller than the preset threshold value in step S1523, the process proceeds to step S1524, and the measurement error determination unit 28 determines that the first spatial coordinates obtained in step S1504 for the light emitting marker 4a are appropriate (normally, The first space coordinates are obtained with higher accuracy than the third space coordinates.), And an appropriate signal is output to the three-dimensional position output unit 34. The three-dimensional position output unit 34 outputs and records the data of the first spatial coordinates to the three-dimensional position recording unit 20. Thereafter, the flow proceeds to step S1525.
[0060]
If the deviation is equal to or larger than the preset threshold value in step S1523, the process proceeds to step S1526, where the measurement error determination unit 28 determines that the first spatial coordinates obtained in step S1504 for the light emitting marker 4a are inappropriate, A predetermined signal is output to the three-dimensional position output unit 34. The three-dimensional position output unit 34 outputs and records the third spatial coordinates to the three-dimensional position recording unit 20 (instead of the first spatial coordinates). Thereafter, the flow proceeds to step S1525.
[0061]
In step S1525, the index r is incremented. If the index r is smaller than 2 in step S1527, the process returns to step S1522, and the processes of steps S1522 to S1526 are repeated for the remaining light emitting markers 4b, and the first or third spatial coordinates are stored in the three-dimensional position recording unit 20. Record.
[0062]
In step S1520, the absolute value | D ₃ -D ₀ If there is no camera 6 whose | is smaller than the preset threshold value, the process proceeds to step S1528, where the measurement error marker determination unit 32 uses the light emission area (not only the first spatial coordinates calculated in step S1505). Then, the third spatial coordinates calculated in step S1515 are also determined to be inappropriate, and an error signal is output to the three-dimensional position output unit 34. Then, the three-dimensional position output unit 34 outputs and records the data of the second spatial coordinates regarding the light-emitting markers 4a and 4b obtained based on the immediately preceding image frame to the three-dimensional position recording unit 20. Thereafter, the flow returns to step S1510.
[0063]
As described above, in the present embodiment, the measurement error marker is specified using the three-dimensional position information calculated using the marker light emission area, so that the effective measurement data regarding the other light emission marker is maximally used. Becomes possible, and continuous marker position measurement becomes possible.
[0064]
Embodiment 5 FIG.
The three-dimensional position measurement system (not shown) according to the present embodiment is different from the measurement systems according to the first to fourth embodiments, and is different from the measurement systems according to the first to fourth embodiments in that one or more light-emitting markers for measurement (for example, in the first embodiment) In addition to the light-emitting markers 4a and 4b), one or more reference light-emitting markers (not shown) which are at a certain distance from the measurement light-emitting marker and are not affected by changes in the light environment or occlusion are measured. Attach to an object (for example, a person). In this case, by calculating the distance between the reference light-emitting marker and the measurement light-emitting marker, the error marker can be immediately specified if a measurement error occurs (without determining the measurement error marker).
[0065]
The specific embodiments of the present invention have been described above, but the present invention is not limited thereto, and various modifications can be made. For example, in the above-described embodiment, for the light-emitting marker that caused the measurement error, the data of the second spatial coordinates obtained using the immediately preceding image frame was recorded in the three-dimensional position recording unit 20. An image camera is further prepared and an image of the luminescent marker is taken, and an image frame taken by the moving image camera and an image frame taken by another moving image camera are used for stereo vision. The three-dimensional position of the measurement error marker may be calculated based on the principle.
[0066]
【The invention's effect】
According to the present invention, when a measurement error occurs, the position information of another light-emitting marker measured when the measurement error occurs can be effectively used by specifying the light-emitting marker that caused the error.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing a first embodiment of a three-dimensional position measurement system according to the present invention.
FIG. 2 is a block diagram illustrating a three-dimensional position calculating unit in FIG. 1;
FIG. 3 is a flowchart showing a first part of a measurement process by the three-dimensional position measurement system of FIG. 1;
FIG. 4 is a flowchart showing a second part of the measurement process by the three-dimensional position measurement system of FIG. 1;
FIG. 5 is a schematic configuration diagram showing Embodiment 3 of a three-dimensional position measurement system according to the present invention.
FIG. 6 is a block diagram showing a three-dimensional position calculator of FIG. 5;
FIG. 7 is a flowchart showing a first part of a measurement process by the three-dimensional position measurement system in FIG. 5;
FIG. 8 is a flowchart showing a second part of the measurement process by the three-dimensional position measurement system of FIG. 5;
FIG. 9 is a schematic configuration diagram showing Embodiment 3 of a three-dimensional position measurement system according to the present invention.
FIG. 10 is a block diagram showing a three-dimensional position calculator of FIG. 9;
FIG. 11 is a flowchart showing a first part of a measurement process by the three-dimensional position measurement system of FIG. 9;
FIG. 12 is a flowchart showing a second part of the measurement process by the three-dimensional position measurement system of FIG. 9;
FIG. 13 is a schematic configuration diagram showing Embodiment 3 of a three-dimensional position measurement system according to the present invention.
FIG. 14 is a block diagram showing a three-dimensional position calculator of FIG. 13;
FIG. 15 is a flowchart showing a first part of a measurement process by the three-dimensional position measurement system in FIG. 13;
FIG. 16 is a flowchart showing a second part of the measurement process by the three-dimensional position measurement system in FIG. 13;
FIG. 17 is a flowchart showing a third part of the measurement process by the three-dimensional position measurement system in FIG. 13;
[Explanation of symbols]
2: 3D measurement system
4a, 4b: luminescence marker
6A, 6B: Video camera
8: Measuring device

Claims (6)

A plurality of light-emitting markers attached to the measurement target,
First and second moving image cameras for imaging the plurality of light emitting markers,
A two-dimensional position calculating unit that calculates planar coordinates of each of the light emitting markers in the first and second images captured by the first and second moving image cameras, respectively;
A stereo vision calculation unit that calculates spatial coordinates of each of the light-emitting markers based on the principle of stereo vision based on the plane coordinates of each of the light-emitting markers in the first and second images calculated by the two-dimensional position calculation unit; ,
A marker distance calculating unit that calculates a distance between the light emitting markers based on the spatial coordinates calculated by the stereo visual calculation unit;
A measurement error determination unit that determines whether the marker distance calculated by the marker distance calculation unit is appropriate,
For each of the light-emitting markers constituting the light-emitting marker pair for which the distance between markers has been determined to be incorrect by the measurement error determination unit, the corresponding first and second images and the first and second images immediately before being determined to be incorrect. A marker moving distance calculating unit that calculates a marker moving distance based on the second image;
A measurement error marker determination unit that determines a light emitting marker that has caused the determination that the distance between the markers is incorrect based on the marker movement distance;
3D position measurement system equipped with. At least three luminescent markers attached to the measurement target;
First and second moving image cameras for imaging the at least three light emitting markers,
A two-dimensional position calculating unit that calculates planar coordinates of each of the light emitting markers in the first and second images captured by the first and second moving image cameras, respectively;
A stereo vision calculation unit that calculates spatial coordinates of each of the light-emitting markers based on the principle of stereo vision based on the plane coordinates of each of the light-emitting markers in the first and second images calculated by the two-dimensional position calculation unit; ,
An inter-marker distance calculation unit that calculates a distance between the light-emitting markers based on the spatial coordinates calculated by the stereo vision calculation unit, and calculates a plurality of inter-marker distances for each of the light-emitting markers.
A measurement error determination unit that determines whether the marker distance calculated by the marker distance calculation unit is appropriate,
For each of the light-emitting markers constituting the light-emitting marker pair for which the inter-marker distance is determined to be incorrect by the measurement error determination unit, an incorrect marker-to-marker distance A measurement error marker determination unit that determines a light-emitting marker that has caused the determination that the distance is present;
3D position measurement system equipped with. A plurality of light-emitting markers attached to the measurement target,
A light emission control unit that controls light emission of the plurality of light emission markers,
First and second moving image cameras for imaging the plurality of light emitting markers,
A two-dimensional position calculating unit that calculates planar coordinates of each of the light emitting markers in the first and second images captured by the first and second moving image cameras, respectively;
Based on the planar coordinates of each light-emitting marker in each image calculated by the two-dimensional position calculating unit, a stereo visual calculation unit that calculates the spatial coordinates of each light-emitting marker based on the principle of stereo vision,
A marker distance calculating unit that calculates a distance between the light emitting markers based on the spatial coordinates calculated by the stereo visual calculation unit;
A measurement error determination unit that determines whether the marker distance calculated by the marker distance calculation unit is appropriate or not,
When the measurement error determination unit determines that the distance between the markers is inappropriate, the light emission control unit replaces each of the light emission markers constituting the light emission marker pair corresponding to the distance between the markers with the first and second moving images. The first and second moving image cameras sequentially emit light in synchronization with a signal for driving an image pickup device of the camera, and the two-dimensional position calculation unit performs image pickup with the first and second moving image cameras, respectively. And calculating different plane coordinates of each light-emitting marker in the first and second images, and the stereo vision calculation unit calculates, for each light-emitting marker, the light-emitting marker in each image calculated by the two-dimensional position calculation unit. A three-dimensional position measurement system, wherein another spatial coordinate is calculated based on another plane coordinate. A plurality of light-emitting markers attached to the measurement target,
First and second moving image cameras for imaging the plurality of light emitting markers,
A two-dimensional position calculating unit that calculates planar coordinates of each of the light emitting markers in the first and second images captured by the first and second moving image cameras, respectively;
Based on the planar coordinates of each light-emitting marker in each image calculated by the two-dimensional position calculating unit, a stereo visual calculation unit that calculates the spatial coordinates of each light-emitting marker based on the principle of stereo vision,
A marker distance calculating unit that calculates a distance between the light emitting markers based on the spatial coordinates calculated by the stereo visual calculation unit;
A measurement error determination unit that determines whether the marker distance calculated by the marker distance calculation unit is appropriate,
For each of the light-emitting markers constituting the light-emitting marker pair for which the distance between markers has been determined to be inappropriate by the measurement error determination unit, the light-emitting markers in the first and second images respectively captured by the first and second moving image cameras are described. A light emitting area calculation unit for calculating a light emitting area,
A calculating unit that calculates another spatial coordinate of each of the light-emitting markers constituting the light-emitting marker pair in which the distance between the markers is determined to be inappropriate by using the light-emitting area calculated by the light-emitting area calculation unit;
A measurement error marker determination unit that determines a light-emitting marker that has caused the determination that the distance between markers is incorrect based on another spatial coordinate calculated by the calculation unit;
3D position measurement system equipped with. One or more measurement light-emitting markers attached to the measurement target, and a reference light-emitting marker having a constant distance from the measurement light-emitting marker,
First and second moving image cameras for imaging the light emitting marker,
A two-dimensional position calculating unit that calculates planar coordinates of each of the light emitting markers in the first and second images captured by the first and second moving image cameras, respectively;
Based on the planar coordinates of each light-emitting marker in each image calculated by the two-dimensional position calculating unit, a stereo visual calculation unit that calculates the spatial coordinates of each light-emitting marker based on the principle of stereo vision,
Based on the spatial coordinates calculated by the stereo vision calculation unit, an inter-marker distance calculation unit that calculates the distance between the reference light-emitting marker and each measurement light-emitting marker,
A measurement error determination unit that determines whether or not the marker distance calculated by the marker distance calculation unit is appropriate for each measurement light-emitting marker, and thereby determines whether the measurement light-emitting marker has caused an error. ,
3D position measurement system equipped with. Imaging the plurality of light-emitting markers attached to the measurement target with the first and second moving image cameras;
Calculating plane coordinates of each of the light emitting markers in the first and second images captured by the first and second moving image cameras, respectively;
Based on the calculated two-dimensional position of each of the light-emitting markers in each image, calculating spatial coordinates of each of the light-emitting markers by the principle of stereo vision,
Calculating a distance between the light-emitting markers based on the calculated spatial coordinates;
A measurement error determination step of determining whether the calculated distance between markers is appropriate,
When it is determined that the distance between the markers calculated in the measurement error determination step is inappropriate, one of the light-emitting markers constituting the light-emitting marker pair corresponding to the distance between the markers is determined to be an inappropriate distance between the markers. A step of determining whether the determination has been caused;
Three-dimensional position measurement method.

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