JP2021162510A - Three-dimensional measuring device - Google Patents

Abstract

To provide a striped pattern image determination method capable of determining a striped pattern image facilitating measurement of a three-dimensional shape of a measurement object with high accuracy in a short time.SOLUTION: A three-dimensional measuring device for measuring the three-dimensional shape of an object to be measured using a phase shift method, which includes a projector for projecting a striped pattern image and a camera. The three-dimensional measuring device includes: a polarizer that polarizes light projected by the projector into linear polarized light; a detector that selectively passes the light from reflected light in at least four vibration directions; a luminance value acquisition unit that acquires the brightness value of light that has passed through the detector (S12); a luminance component calculation unit (S13) that calculates the fluctuation range of the brightness value due to the difference in the vibration direction of the light passed through the detector and the base value of brightness value regardless of the difference in vibration direction of light passed by the detector based on the acquired brightness value; and a shape calculation unit (S14) that compares the fluctuation range with the base value, and calculates the three-dimensional shape of the object to be measured using the smaller one as the brightness value for shape calculation.SELECTED DRAWING: Figure 6

Description

The present invention relates to a three-dimensional measuring device that measures a three-dimensional shape of an object by a phase shift method.

As disclosed in Patent Document 1, a device using the phase shift method is known as a three-dimensional measuring device for measuring the three-dimensional shape of a measurement object. In the phase shift method, a plurality of fringe pattern images with different phases are projected, and the measurement object on which the fringe pattern images are projected is photographed. Then, based on the brightness of each point of the measurement object, the coordinates of each point of the measurement object are determined by the principle of triangulation.

Japanese Unexamined Patent Publication No. 2014-202492

If the object to be measured is a mirror object, the image of the object to be measured may be overexposed. If the captured image is overexposed, the measurement accuracy of the three-dimensional shape by the phase shift method is lowered.

Further, when the object to be measured is a translucent object, light may not be reflected on the surface and internal reflection may be detected. If the three-dimensional shape is measured based on the internally reflected light, the measurement accuracy of the three-dimensional shape is lowered.

The present disclosure has been made based on this circumstance, and an object of the present invention is to provide a three-dimensional measuring device capable of accurately measuring a three-dimensional shape of a measurement object.

The above object is achieved by a combination of the features described in the independent claims, and the sub-claims provide further advantageous specific examples. The reference numerals in parentheses described in the claims indicate, as one embodiment, the correspondence with the specific means described in the embodiments described later, and do not limit the disclosed technical scope.

The three-dimensional measuring device for achieving the above purpose is
A projector (20) that projects a striped pattern image and
It is equipped with a camera (40, 140) that captures a striped pattern image projected on the measurement object (5).
It is a three-dimensional measuring device that measures the three-dimensional shape of the object to be measured by the phase shift method based on the brightness value of the image taken by the camera.
A polarizer (30) that converts the light projected by the projector into linearly polarized light,
An detector (41, 141) that selectively passes light in at least four vibration directions from the reflected light reflected by the object to be measured, and the light representing the fringe pattern image.
A luminance value acquisition unit (S12) that acquires a luminance value of light that has passed through an detector and is detected by a camera, and a luminance value acquisition unit (S12).
Based on the brightness value acquired by the brightness value acquisition unit, the fluctuation range of the brightness value due to the difference in the vibration direction of the light passed by the analyzer and the base value of the brightness value regardless of the difference in the vibration direction of the light passed by the detector. Luminance component calculation unit (S13) that calculates
It is provided with a shape calculation unit (S14) that compares the fluctuation width with the base value and uses the smaller one as the brightness value for shape calculation to calculate the three-dimensional shape of the object to be measured.

This three-dimensional measuring device projects linearly polarized light onto the object to be measured. Therefore, the vibration direction of the specular reflection component from the measurement object is a specific direction. Further, this three-dimensional measuring device includes an analyzer that selectively passes light in at least four vibration directions from the reflected light. Since the photon selectively passes light having a different vibration direction, the specular reflection component of the light passing through the photon has a different brightness depending on the vibration direction of the light passed by the photon.

On the other hand, the reflected light from the object to be measured contains a diffuse reflection component. The diffuse reflection component includes light having various directions of vibration of the electric field. In other words, the diffuse reflection component can be considered to be substantially constant regardless of the vibration direction of the light. Therefore, the diffuse reflection component of the reflected light is substantially the same regardless of the vibration direction of the light passed by the detector.

From these facts, it can be considered that the fluctuation range when comparing the brightness values that have passed through the analyzer for four or more vibration directions is the magnitude of the specular reflection component of the reflected light. Further, when comparing the brightness values that have passed through the detector for four or more vibration directions, it is considered that the base value, which is a portion that does not depend on the vibration direction that the detector passes through, is the diffuse reflection component of the reflected light. Can be done.

If the object to be measured is a mirror-finished object, the brightness value does not reflect the three-dimensional shape because the value may be saturated if the specular reflection component is used. Therefore, a base value representing the brightness value of the diffuse reflection component is used. In the case of a mirror-finished object, the base value of the luminance value representing the diffuse reflection component is smaller than the fluctuation range of the luminance value representing the specular reflection component.

Further, when the object to be measured is a translucent object, diffuse reflection may occur inside the object to be measured. Therefore, when the object to be measured is a translucent object, the diffuse reflection component of the luminance value does not accurately represent the three-dimensional shape. Therefore, if the object to be measured is a translucent object, it is preferable to use a specular reflection component. The specular reflection component is a fluctuation range, and when the object to be measured is a translucent object, the fluctuation range is smaller than the base value.

Next, consider the case where the object to be measured is an object that is neither a mirror object but a translucent object (hereinafter, a normal object). An ordinary object is an object whose diffuse reflection on the surface of the object is the main component of the reflected light. For a normal object, the specular reflection component of the reflected light may be used or the diffuse reflection component may be used for the brightness value for measuring the three-dimensional shape.

However, it is not possible to distinguish whether the diffuse reflection component is a surface diffusion component or an internal diffusion reflection component. If the specular reflection component is used, it is not necessary to distinguish between them. Therefore, for a normal object, the specular reflection component can be used. In a normal object, the specular reflection component is considered to be smaller than the diffuse reflection component.

Summarizing the above, regardless of whether the object to be measured is a mirror object, a translucent object, or a normal object, the fluctuation width and the base value are compared, and the smaller one is the brightness for shape calculation. It can be used as a value.

The shape calculation unit compares the fluctuation width with the base value and calculates the three-dimensional shape of the object to be measured by using the smaller one as the brightness value for shape calculation. Therefore, the three-dimensional shape can be calculated accurately regardless of the surface texture of the object to be measured.

Further, when the object to be measured is a mirror object, the purpose can be achieved by the following three-dimensional measuring device. That is,
A three-dimensional measuring device that measures the three-dimensional shape of a mirrored object by the phase shift method.
A projector (20) that projects a striped pattern image and
Cameras (40, 140) that capture the striped pattern image projected on the measurement object (5), and
A polarizer (30) that converts the light projected by the projector into linearly polarized light,
An detector (41, 141) that selectively passes light in at least four vibration directions from the reflected light reflected by the object to be measured, and the light representing the fringe pattern image.
A luminance value acquisition unit (S12) that acquires a luminance value of light that has passed through an detector and is detected by a camera, and a luminance value acquisition unit (S12).
A luminance component calculation unit (S23) that calculates a base value of the luminance value based on the luminance value acquired by the luminance value acquisition unit regardless of the difference in the vibration direction of the light passed by the analyzer.
A shape calculation unit (S24) for calculating the three-dimensional shape of the object to be measured by using the base value calculated by the brightness component calculation unit as the brightness value for shape calculation is provided.

When it is known that the object to be measured is a mirror object, the comparison between the base value of the brightness value and the fluctuation width is omitted as in this three-dimensional measuring device, and the base value of the brightness value is used for shape calculation. The three-dimensional shape of the object to be measured can be measured by using it as a brightness value. This three-dimensional measuring device also uses the base value of the brightness value as the brightness value for shape calculation to calculate the three-dimensional shape of the object to be measured, so that the three-dimensional shape of the mirrored object can be calculated accurately. can.

Further, when the object to be measured is a translucent object, the purpose can be achieved by the following three-dimensional measuring device. That is,
A three-dimensional measuring device that measures the three-dimensional shape of a translucent object by the phase shift method.
A projector (20) that projects a striped pattern image and
Cameras (40, 140) that capture the striped pattern image projected on the measurement object (5), and
A polarizer (30) that converts the light projected by the projector into linearly polarized light,
An detector (41, 141) that selectively passes light in at least four vibration directions from the reflected light reflected by the object to be measured, and the light representing the fringe pattern image.
A luminance value acquisition unit (S12) that acquires a luminance value of light that has passed through an detector and is detected by a camera, and a luminance value acquisition unit (S12).
Based on the luminance value acquired by the luminance value acquisition unit, the luminance component calculation unit (S33) that calculates the fluctuation range of the luminance value due to the difference in the vibration direction of the light passed by the analyzer, and the luminance component calculation unit (S33).
A shape calculation unit (S34) for calculating the three-dimensional shape of the object to be measured by using the fluctuation width calculated by the brightness component calculation unit as the brightness value for shape calculation is provided.

When it is known that the object to be measured is a translucent object, the comparison between the base value of the brightness value and the fluctuation width is omitted and the fluctuation width of the brightness value is used for shape calculation as in this three-dimensional measuring device. The three-dimensional shape of the object to be measured can be measured by using it as the brightness value of. This three-dimensional measuring device also calculates the three-dimensional shape of the object to be measured by using the fluctuation range of the brightness value as the brightness value for shape calculation, so that the three-dimensional shape of the translucent object can be calculated accurately. Can be done.

Further, in the three-dimensional measuring device, the camera (40) can be a polarized camera provided with four types of detectors (41) having different vibration directions of the light passing through each other. When a polarized camera is provided, it is not necessary to separately arrange an analyzer in front of the optical path of the camera.

Further, in the three-dimensional measuring device, the analyzer (141) may be arranged in front of the camera (140) in the optical path of the reflected light. In this way, a camera other than a polarized camera can be used.

The figure which shows the structure of the 3D measuring apparatus 1 of embodiment. The figure which shows the stripe pattern image. The figure which shows the repeating unit of the analyzer 41 included in the camera 40. The figure which shows a part of the arrangement of the analyzer 41. The figure which shows the color filter provided in the camera 40. The figure which shows the process of measuring a three-dimensional shape in 1st Embodiment. The figure which shows the relationship between the polarization angle and the light intensity detected by a photodetection element. It is a figure explaining the calculation method of the horizontal coordinates (xm, ym). The figure which shows the process of measuring a three-dimensional shape in 2nd Embodiment. The figure which shows the process of measuring a three-dimensional shape in 3rd Embodiment. The figure which shows the structure of the 3D measuring apparatus 100 of 4th Embodiment.

<First Embodiment>
Hereinafter, embodiments will be described with reference to the drawings. FIG. 1 is a diagram showing a configuration of the three-dimensional measuring device 1 of the first embodiment. The three-dimensional measuring device 1 includes a control device 10, a projector 20, a polarizer 30, and a camera 40. The three-dimensional measuring device 1 measures the three-dimensional shape of the measurement object 5 placed on the work table 2 by the phase shift method. The upper surface of the workbench 2 is a flat surface, and the measurement object 5 is located at an arbitrary position on the workbench 2. The three-dimensional measuring device 1 is used, for example, as the eyes of the robot when the robot is made to perform picking, assembling work, product inspection, and the like.

The control device 10 may be equipped with a computer. The control device 10 generates image data which is the data of the image projected by the projector 20 and outputs the image data to the projector 20. The image projected by the projector 20 includes a striped pattern image.

Further, the control device 10 acquires image data representing an image taken by the camera 40 in a state where the striped pattern image is projected from the projector 20 onto the measurement object 5. Then, the three-dimensional shape of the measurement object 5 is measured by the phase shift method based on the image data.

FIG. 2 shows a striped pattern image. The striped pattern image of the present embodiment is a color striped pattern image. In addition, unlike this, a monochromatic striped pattern image may be projected. The fringe pattern image shown in FIG. 2 is, in detail, a composite fringe pattern image obtained by synthesizing a three-color monochromatic fringe pattern image in which the brightness is changed in the brightness range from 0 to 255 for all of red, green, and blue.

The monochromatic striped pattern image is an image in which the brightness of any one of red, green, and blue changes in a sinusoidal manner in one direction of the image, and the brightness is constant in the direction orthogonal to the one direction. In the composite fringe pattern image, the phases of the three-color single-color fringe pattern image are shifted by a predetermined angle.

As an example, the phase of the red monochromatic stripe pattern image is the most advanced, and the phase of the green monochromatic stripe pattern image is 2π / 3 behind that. The blue monochromatic stripe pattern image is further out of phase by 2π / 3 from the green monochromatic stripe pattern image. Since the striped pattern image is an image in which red, green, and blue monochromatic striped pattern images are evenly included, the color changes in a rainbow shape as the x-pixel coordinates change.

The projector 20 is a projector capable of projecting a color image. The striped pattern image projected by the projector 20 passes through the polarizer 30 and is projected onto the measurement object 5. The polarizer 30 converts the light projected by the projector 20 into linearly polarized light. The polarization direction by the polarizer 30 is not particularly limited.

The camera 40 is a digital camera capable of capturing a color image, and is provided with a large number of photodetecting elements (that is, pixels) such as a photodiode on the light receiving surface in the vertical and horizontal directions. The camera 40 is a polarized camera. The camera 40, which is a polarized camera, includes the analyzer 41 shown in FIG. 3 in front of the optical path of the image sensor. FIG. 3 shows a repeating unit of the analyzer 41. Specifically, the detector 41 is divided into four types of detectors 41a, 41b, 41c, and 41d, which have different vibration directions of the light passing through each other. When these four types of detectors 41a, 41b, 41c, and 41d are not distinguished, they are described as detector 41.

The four types of detectors 41a, 41b, 41c, and 41d of the present embodiment have the same angular difference in the vibration direction of the passing light at 45 degrees. Assuming that the vibration direction of the light passing through the detector 41a is 0 degrees, the vibration direction of the light passing through the detector 41b is 45 degrees, the vibration direction of the light passing through the detector 41c is 90 degrees, and the light passing through the detector 41d is passed. The vibration direction of light is 135 degrees.

FIG. 4 shows a part of the arrangement of the analyzer 41. As shown in FIG. 4, repeating units containing four types of detectors 41, one for each, are arranged continuously in the vertical and horizontal directions. The RGB color filter shown in FIG. 5 is arranged between the analyzer 41 and the photodetector.

In the RGB color filter, any one of red, green, and blue color filters is arranged in the light arrival direction with respect to each light detection element. The arrangement of red, green, and blue color filters generally follows the Bayer arrangement. In FIG. 5, R means a red filter, G means a green filter, and B means a blue filter.

The minimum unit of the filter of each color corresponds to one detector 41. The minimum unit of each color filter is arranged vertically and horizontally. Therefore, the light that has passed through all four types of detectors 41 is incident on each color filter. The filters are arranged according to the Bayer array with the size of four minimum units as one repeating unit.

[Processing to measure 3D shape]
Next, the process of measuring the three-dimensional shape will be described. FIG. 6 shows a process for measuring a three-dimensional shape. The process shown in FIG. 6 is executed by the control device 10 based on the operation of the user. In step (hereinafter, step is omitted) S11, the striped pattern image is projected on the measurement object 5, and the image of the measurement object 5 at that time is captured by the camera 40.

In S12, the captured images of the three colors of red, green, and blue are acquired for each type of the analyzer 41. This means that the brightness value detected by the pixel is acquired for each color of the color filter and for each type of the analyzer 41. This S12 corresponds to the brightness value acquisition unit.

S13 corresponds to the luminance component calculation unit. In S13, the polarization analysis is performed using the captured images for each color and each type of the analyzer 41. The ellipsometry calculates Imax-Imin and Imin shown in FIG. 7.

The horizontal axis of FIG. 7 is the polarization angle. The polarization angle means the vibration direction of the light passed through the four types of detectors 41. The vertical axis is the light intensity detected by each pixel, that is, the brightness value. Therefore, Imax-Imin is the fluctuation range of the luminance value due to the difference in the analyzer 41, and Imin is the base value of the luminance value not depending on the analyzer 41.

Here, assuming that the luminance value is detected by continuously changing the polarization angle, as shown in FIG. 7, the change in the luminance value with respect to the polarization angle should be sinusoidal. Therefore, if the brightness value detected by the pixel is I, the polarization angle is θ, and the initial value of the polarization angle is φ, Equation 1 holds.

式１において、（１＋ｓｉｎ（２×（θ＋φ）））／２は、最大値が１、最小値が０であり、「θ＋φ」は図７に示す正弦波の各偏光角度における位相を意味する。変動幅であるＩｍａｘ−Ｉｍｉｎに、（１＋ｓｉｎ（２×（θ＋φ）））／２を乗じた右辺第１項は、各偏光角度における変動成分の大きさを意味する。

In Equation 1, (1 + sin (2 × (θ + φ))) / 2 has a maximum value of 1 and a minimum value of 0, and “θ + φ” means the phase of the sine wave shown in FIG. 7 at each polarization angle. The first term on the right side, which is obtained by multiplying Imax-Imin, which is the fluctuation range, by (1 + sin (2 × (θ + φ))) / 2, means the magnitude of the fluctuation component at each polarization angle.

In Equation 1, Imax, Imin, θ, and φ are unknowns, and I is the luminance value detected by each pixel. I can be obtained at four polarization angles, 0 degree, 45 degree, 90 degree, and 135 degree. Therefore, since four equations can be obtained for four unknowns, Imax, Imin, θ, and φ can be obtained by solving simultaneous equations. Then, when Imax and Imin are obtained, the fluctuation range of the luminance value, that is, Imax-Imin is calculated from them.

Here, the meaning of the luminance component represented by the fluctuation range and the base value will be described. As also shown in FIG. 7, the fluctuation width represents the specular reflection component of the reflected light, and the base value represents the diffuse reflection component of the reflected light. Further, as can be seen from FIG. 7, the specular reflection component is an AC component of the reflected light, and the diffuse reflection component is a DC component of the reflected light.

Next, the reason why the fluctuation width represents the specular reflection component of the reflected light will be described. The three-dimensional measuring device 1 of the present embodiment includes a polarizer 30 and projects linearly polarized light onto the measurement object 5. When specularly reflected, the reflected light also maintains linearly polarized light. The more the polarization angle of the detector 41 matches the angle of the linearly polarized light of the reflected light, the larger the brightness value detected by the pixel corresponding to the detector 41. That is, the magnitude of the specular reflection component of the reflected light detected in each pixel changes due to the difference in the polarization angle of the analyzer 41 arranged in front of each pixel. Therefore, the fluctuation width represents the specular reflection component of the reflected light.

Next, the reason why the base value represents the diffuse reflection component of the reflected light will be described. Even if the light projected on the measurement object 5 is linearly polarized light, the diffuse reflection component becomes omnidirectional light. Since it is omnidirectional light, the magnitude of the diffuse reflection component is almost the same regardless of the polarization angle. Therefore, it can be considered that the base value represents the diffuse reflection component of the reflected light.

S14 corresponds to the shape calculation unit. Specifically, S14 is S15 or less. In S15, the brightness value for shape calculation is determined for each color. The luminance value for shape calculation is a smaller value when the fluctuation width calculated in S13 is compared with the base value.

The reason for this will be explained. When the object 5 to be measured is a mirror-finished object, the brightness value does not represent a three-dimensional shape because the value may be saturated if the specular reflection component is used. On the other hand, even in a mirrored object, the reflected light usually contains a diffuse reflection component to some extent. If it is a diffuse reflection component contained in the reflected light from the mirrored object, it is not saturated. Therefore, when the measurement object 5 is a mirror surface object, it is preferable to use a diffuse reflection component. When comparing the specular reflection component and the diffuse reflection component in the reflected light from the mirror object, the diffuse reflection component is smaller.

Next, consider the case where the measurement object 5 is a translucent object. In a translucent object, diffuse reflection may occur inside the measurement object 5. Therefore, when the object 5 to be measured is a translucent object, the diffuse reflection component of the luminance value does not accurately represent the three-dimensional shape. Therefore, if the object 5 to be measured is a translucent object, it is preferable to use a specular reflection component. This is because specular reflection is a reflection that occurs on the surface of an object. The specular reflection component of a translucent object is not large. Therefore, the specular reflection component of a translucent object is smaller than the diffuse reflection component.

Next, consider the case where the measurement object 5 is a normal object. A normal object is an object that is neither a mirror object nor a translucent object. If it is a normal object, a specular reflection component may be adopted, or a diffuse reflection component may be adopted. However, when measuring the surface shape of an arbitrary object, the measurement object 5 may be a translucent object. Diffuse reflection is difficult to distinguish between diffuse reflection inside an object and diffuse reflection on the surface of an object. Therefore, if it is a normal object, the specular reflection component may be used. In a normal object, the specular reflection component is smaller than the diffuse reflection component.

From the above, regardless of whether the object is a mirror-finished object, a translucent object, or a normal object, the diffuse reflection component and the specular reflection component may be compared and the smaller one may be adopted.

In S16, the luminance value for shape calculation determined in S15 is normalized for each color. In S17, the phase θ (x, y) at each coordinate (x, y) is calculated from Equation 2 based on the luminance value normalized for each color of each coordinate (x, y). As described with reference to FIG. 5, in the present embodiment, a total of four pixels, two vertically and horizontally for each color, are one repeating unit. The coordinates here are the coordinates for each repeating unit. For example, the center coordinates of the four pixels are used as the coordinates here.

式２において、Ｎは位相シフト総回数、ｎは色別に取得した撮影画像の位相シフト回数である。縞パターン画像において最も早い位相とした色のｎが０、次に位相が早い色のｎが１、最も位相が遅い色のｎが２である。位相シフト総回数Ｎは３である。また、ａ（ｘ、ｙ）は輝度振幅、ｂ（ｘ、ｙ）は背景輝度、θ（ｘ、ｙ）はｎ＝０での位相θである。

In Equation 2, N is the total number of phase shifts, and n is the number of phase shifts of the captured image acquired for each color. In the fringe pattern image, n of the color having the earliest phase is 0, n of the color having the next earliest phase is 1, and n of the color having the latest phase is 2. The total number of phase shifts N is 3. Further, a (x, y) is the luminance amplitude, b (x, y) is the background luminance, and θ (x, y) is the phase θ at n = 0.

In Equation 2, there are three unknowns, a (x, y), b (x, y), and θ (x, y). Therefore, if the luminance values of the coordinates (x, y) of the three captured images determined by color in S16 are used, the three unknowns including the phase θ, a (x, y), b (x, y). , Θ (x, y) can be calculated.

In S18, the height coordinate zm of the coordinate measurement point P is determined from the phase θ (x, y) of each coordinate (x, y) calculated in S17. The coordinate measurement point P is a point on the surface of the measurement object 5 or the workbench 2.

The height coordinate zm is the distance from the plane including the projector 20 and the camera 40 to the object. The height coordinate zm is determined by using a graph showing the relationship between the phase θ and the height coordinate zm and the phase θ calculated in S17. A graph showing the relationship between the phase θ and the height coordinate zm can be created if the coordinates of the projector 20, the coordinates of the camera 40, the height coordinates zm, and the length of one cycle of the fringe pattern image on the reference plane are known. can. The reference plane is a plane parallel to the projection plane, which is the surface of the workbench 2, and the distance between the projector 20 and the camera 40 is zm.

If the projector 20 and the camera 40 are fixed, the coordinates of the projector 20 and the coordinates of the camera 40 become known. Further, the height coordinate zm to the reference plane is a given value. Further, if the height coordinate zm to the reference plane is determined, the length of one cycle of the fringe pattern image on the reference plane is also determined. Therefore, a graph showing the relationship between the phase θ and the height coordinate zm can be obtained in advance.

A graph showing the relationship between the phase θ and the height coordinate zm is obtained in advance, and in S18, the phase θ (x, y) calculated in S17 is applied to the graph obtained in advance, and each coordinate measurement point is obtained. The height coordinate zm of P is determined. If it is unknown how many cycles the phase θ is, the height coordinate zm cannot be determined either. However, the height coordinate zm at a certain coordinate measurement point P continuously changes with respect to the height coordinate zm of the coordinate measurement point P adjacent to the coordinate measurement point P. Therefore, the three-dimensional shape of the measurement object 5 can be measured even if it is unknown how many cycles the phase θ is. Further, since the height coordinate zm of the workbench 2 is known, the height coordinate zm of the coordinate measurement point P may be determined by comparing with the height coordinate zm of the workbench 2.

In S19, the horizontal coordinates (xm, ym) are determined for the coordinate measurement point P for which the height coordinate zm is determined in S18. The height coordinates zm determined in S18 are associated with the coordinates on the pixels. Once the coordinates on the pixels are determined, the directions (αx, αy) with respect to the camera 40 are determined. As shown in FIG. 8, αx is an angle between the direction from the camera 40 toward the coordinate measurement point P and the zm axis in the xmzm plane. Although αy is not shown in FIG. 8, αy is an angle between the direction from the camera 40 toward the coordinate measurement point P and the zm axis in the ymzm plane. As can be seen from FIG. 8, the horizontal coordinates (xm, ym) can be calculated by geometric calculation from the height coordinates zm and αm, αy.

By executing the process of S14 for each coordinate (x, y), the three-dimensional shape of the measurement object 5 can be measured.

[Summary of Embodiment]
In the present embodiment described above, the linearly polarized fringe pattern image is projected onto the measurement object 5 by the polarizer 30. Further, the camera 40 includes four detectors 41 having different polarization angles. With this configuration, the fluctuation range of the luminance value (that is, the magnitude of the specular reflection component of the reflected light) and the base value of the luminance value (that is, the magnitude of the diffuse reflection component) can be determined (S13). Then, by comparing the fluctuation width and the base value and setting the smaller one as the luminance value for shape calculation (S15), the three-dimensional shape of the measurement object 5 can be accurately obtained regardless of the properties of the measurement object 5. Can be calculated.

Further, since the polarizing camera is used as the camera 40, it is not necessary to arrange the analyzer in front of the camera 40.

<Second Embodiment>
Next, the second embodiment will be described. In the following description of the second embodiment, the elements having the same number as the codes used so far are the same as the elements having the same code in the previous embodiments, unless otherwise specified. Further, when only a part of the configuration is described, the embodiment described above can be applied to the other parts of the configuration.

The second embodiment is an embodiment that can be applied when it is known in advance that the measurement object 5 is a mirror surface object. FIG. 9 shows a process to be executed in place of FIG. 6 in the second embodiment. In FIG. 9, the same S11 and S12 as in FIG. 6 are executed to acquire captured images for each of the three colors of red, green, and blue for each type of analyzer 41.

Subsequently, S23 and S24 are executed instead of S13 and S14 in FIG. S23 performs the same calculation as S13 to obtain Imax, Imin, θ, and φ. The difference from S13 is that Imax-Imin is not calculated.

Specifically, S24 is the processing of S26, S27, S28, and S29. These S26, S27, S28, and S29 are the same or similar processes as S16, S17, S18, and S19, respectively. Although S15 was included in S14, S24 does not have a process corresponding to S15. When the object 5 to be measured is a mirrored object, it is known that Imin, which is a base value, may be used as the brightness value for shape calculation. Therefore, it is not necessary to compare the magnitude of the fluctuation range of the luminance value with the magnitude of the base value.

In S26, the Imin of each coordinate (x, y), which is the brightness value for shape calculation in the second embodiment, is normalized for each color. S27, S28, and S29 are the same as S17, S18, and S19, respectively. Therefore, in S27, the phase θ (x, y) at each coordinate (x, y) is calculated from Equation 2 based on the luminance value normalized for each color of each coordinate (x, y). In S28, the height coordinate zm of the coordinate measurement point P is determined from the phase θ (x, y) of each coordinate (x, y) calculated in S27. In S29, the horizontal coordinates (xm, ym) of the coordinate measurement point P for which the height coordinate zm is determined in S28 are calculated from the height coordinates zm and αm, αy by geometric calculation.

When it is known that the object 5 to be measured is a mirrored object, the comparison between the base value of the luminance value and the fluctuation range is omitted as in the second embodiment, and Imin, which is the base value of the luminance value, is used. The three-dimensional shape of the measurement object 5 can be measured by using it as a brightness value for shape calculation.

<Third Embodiment>
The third embodiment is an embodiment that can be applied when it is known in advance that the measurement object 5 is a translucent object. FIG. 10 shows a process to be executed instead of FIG. 6 in the third embodiment. In FIG. 10, the same S11 and S12 as in FIG. 6 are executed to acquire captured images for each of the three colors of red, green, and blue for each type of analyzer 41.

Subsequent S33 is the same as S13 in FIG. 6, and Imax, Imin, θ, and φ are obtained, and further, Imax-Imin is calculated from Imax and Imin.

Specifically, S34 is the processing of S36, S37, S38, and S39. These S36, S37, S38, and S39 are the same or similar processes as S16, S17, S18, and S19, respectively. Although S15 was included in S14, S34 does not have a process corresponding to S15. When the object 5 to be measured is a translucent object, it is known that Imax-Imin, which is a fluctuation range, may be used for the brightness value for shape calculation. Therefore, it is not necessary to compare the magnitude of the fluctuation range of the luminance value with the magnitude of the base value.

In S36, Imax-Imin of each coordinate (x, y), which is a luminance value for shape calculation in the third embodiment, is normalized for each color. S37, S38, and S39 are the same as S17, S18, and S19, respectively. Therefore, in S37, the phase θ (x, y) at each coordinate (x, y) is calculated. In S38, the height coordinate zm of the coordinate measurement point P is determined. In S39, the horizontal coordinates (xm, ym) of the coordinate measurement point P are calculated.

When it is known that the measurement object 5 is a translucent object, the comparison between the base value of the luminance value and the fluctuation width is omitted as in the third embodiment, and Imax-Imin which is the fluctuation width of the luminance value is omitted. Can be used as the brightness value for shape calculation to measure the three-dimensional shape of the measurement object 5.

<Fourth Embodiment>
FIG. 11 shows the configuration of the three-dimensional measuring device 100 of the fourth embodiment. The three-dimensional measuring device 100 includes a camera 140 that is not a polarized camera. Then, one detector 141 is arranged at a position in front of the camera 140 in the optical path of the reflected light rather than the camera 140. The detector 141 has, for example, a circular lamellae and is rotatable around a central axis penetrating in the thickness direction.

The detector 141 can be fixed at an arbitrary rotation angle around its central axis. Therefore, assuming that a certain rotation angle is 0 degrees, the rotation angles can be fixed at 0 degrees, 45 degrees, 90 degrees, and 135 degrees. The state fixed at these four rotation angles is a state in which light in four vibration directions different from each other is selectively passed.

When measuring the three-dimensional shape of the object 5 to be measured by using the three-dimensional measuring device 100, in S11, the rotation angles of the analyzer 141 are set to four or more kinds of rotation angles, and the stripe pattern image is projected at each rotation angle. Then, the measurement object 5 may be photographed.

As the three-dimensional measuring device 100, a camera 140 that is not a polarized camera can be used. Also, all pixels detect the brightness with the same polarization angle. Therefore, the resolution of the three-dimensional shape can be improved.

Although the embodiments have been described above, the disclosed technology is not limited to the above-described embodiments, and the following modifications are also included in the disclosed scope, and further, within a range other than the following that does not deviate from the gist. It can be implemented with various changes.

<Modification example 1>
In the embodiment, a color striped pattern image is projected. However, three monochromatic striped pattern images that are out of phase with each other may be projected.

<Modification 2>
The analyzer 141 of the fourth embodiment was configured to be rotatable. However, instead of being rotatably configured, the detector 141 can be attached to and detached from a predetermined mounting member, and even if the detectors 141 having different polarization directions are sequentially mounted on the mounting member. good.

1: Three-dimensional measuring device 2: Work table 5: Object to be measured 10: Control device 20: Projector 30: Polarizer 40: Camera 41: Detector 100: Three-dimensional measuring device 140: Camera 141: Detector S12: Luminance value Acquisition unit S13: Luminance component calculation unit S14: Shape calculation unit S23: Luminance component calculation unit S24: Shape calculation unit S33: Luminance component calculation unit S34: Shape calculation unit

Claims (5)

A projector (20) that projects a striped pattern image and
A camera (40, 140) for capturing the striped pattern image projected on the measurement object (5) is provided.
A three-dimensional measuring device that measures the three-dimensional shape of the object to be measured by the phase shift method based on the brightness value of the image taken by the camera.
A polarizer (30) that linearly polarizes the light projected by the projector, and
An detector (41, 141) that selectively allows light representing the striped pattern image to pass light in at least four vibration directions from the reflected light reflected by the measurement object.
A luminance value acquisition unit (S12) that passes through the analyzer and acquires a luminance value of light detected by the camera, and a luminance value acquisition unit (S12).
Based on the brightness value acquired by the brightness value acquisition unit, the fluctuation width of the brightness value due to the difference in the vibration direction of the light passed by the analyzer and the difference in the vibration direction of the light passed by the detector do not depend on the difference. The luminance component calculation unit (S13) that calculates the base value of the luminance value, and
A three-dimensional measuring device including a shape calculation unit (S14) that compares the fluctuation width with the base value and uses the smaller one as a luminance value for shape calculation to calculate the three-dimensional shape of the measurement object. .. A three-dimensional measuring device that measures the three-dimensional shape of a mirrored object by the phase shift method.
A projector (20) that projects a striped pattern image and
Cameras (40, 140) that capture the striped pattern image projected on the measurement object (5), and
A polarizer (30) that linearly polarizes the light projected by the projector, and
An detector (41, 141) that selectively allows light representing the striped pattern image to pass light in at least four vibration directions from the reflected light reflected by the measurement object.
A luminance value acquisition unit (S12) that passes through the analyzer and acquires a luminance value of light detected by the camera, and a luminance value acquisition unit (S12).
A luminance component calculation unit (S23) that calculates a base value of the luminance value based on the luminance value acquired by the luminance value acquisition unit regardless of the difference in the vibration direction of the light passed by the analyzer.
A three-dimensional measuring device including a shape calculating unit (S24) that calculates a three-dimensional shape of the measurement object by using the base value calculated by the brightness component calculating unit as a brightness value for shape calculation. A three-dimensional measuring device that measures the three-dimensional shape of a translucent object by the phase shift method.
A projector (20) that projects a striped pattern image and
Cameras (40, 140) that capture the striped pattern image projected on the measurement object (5), and
A polarizer (30) that linearly polarizes the light projected by the projector, and
An detector (41, 141) that selectively allows light representing the striped pattern image to pass light in at least four vibration directions from the reflected light reflected by the measurement object.
A luminance value acquisition unit (S12) that passes through the analyzer and acquires a luminance value of light detected by the camera, and a luminance value acquisition unit (S12).
Based on the brightness value acquired by the brightness value acquisition unit, the brightness component calculation unit (S33) that calculates the fluctuation range of the brightness value due to the difference in the vibration direction of the light passed by the analyzer, and the brightness component calculation unit (S33).
A three-dimensional measuring device including a shape calculating unit (S34) that calculates a three-dimensional shape of the measurement object by using the fluctuation width calculated by the brightness component calculating unit as a brightness value for shape calculation. The three-dimensional measuring device according to any one of claims 1 to 3.
The camera (40) is a three-dimensional measuring device, which is a polarized camera including four types of detectors (41) having different vibration directions of light passing through each other. The three-dimensional measuring device according to any one of claims 1 to 3.
The analyzer (141) is a three-dimensional measuring device arranged in front of the camera (140) in the optical path of the reflected light.

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