JP4889373B2 - Three-dimensional shape measuring method and apparatus - Google Patents

Description

  The present invention relates to a method and apparatus for measuring a three-dimensional shape, and more specifically, a method for measuring a three-dimensional shape using a spatial coding method for generating an absolute code value for a space using a binary projection pattern and the same. Relates to the device.

  In general, there are a passive measurement method and an active measurement method as a technique for measuring the three-dimensional shape of a measurement object in a non-contact manner using light.

  Here, the passive measurement method is a method of measuring using ambient light without having a light projecting unit on the measurement device side, as represented by a stereo method.

  On the other hand, the active measurement method is a method of irradiating light from a light projecting means on the measurement device side toward a measurement object and measuring the reflected light.

  Among these active measurement methods, the slit light projection method and the spatial encoding method are known as methods using the principle of triangulation.

Here, the spatial encoding method refers to a binarized projection pattern (hereinafter referred to as a “binarized projection pattern”) which is a stripe-shaped light pattern made up of a light transmission region and a light non-transmission region with respect to a measurement object. When appropriately observing one point on the measurement object on which the striped light pattern is projected by projecting several types of “slit patterns” as appropriate, the projected point is The projected light beam blinks to form a code, and this is a method of measuring the three-dimensional shape of the measurement object using the code.

  1A, 1B, 1C, and 1D show examples of various binarized projection patterns used in the spatial coding method, that is, slit patterns.

  Each of these binarized projection patterns includes a slit-like light transmission region 100a having a constant width W and extending in a predetermined direction orthogonal to the width W direction, and a light non-transmission region 100b corresponding to a slit frame. It is formed so as to be continuous alternately. The width W between the light transmission region 100a and the light non-transmission region 100b can be set to an arbitrary size.

  In the binarized projection patterns shown in FIGS. 1A, 1B, 1C, and 1D, the binarized projection pattern having the smallest width W is the one shown in FIG. As described above, the binarized projection pattern having the narrowest width W among a plurality of different binarized projection patterns is generally referred to as an “LSB pattern”.

  In addition, since such a binarized projection pattern is a conventionally well-known technique, the detailed description is abbreviate | omitted.

  In such a spatial encoding method, the value indicated by the code (spatial code value) and the direction of the light beam have a one-to-one relationship, and the direction of the line of sight of the observation position from the position of the light spot on the measurement object is determined. Since the direction of the light beam can be determined from the spatial code value of the light spot, the distance to all the light spots on the measurement object can be obtained by the principle of triangulation, and thereby the three-dimensional of the measurement object The shape can be measured in a non-contact manner.

In general, a three-dimensional shape measuring apparatus using the above-described spatial encoding method is configured to control the entire operation by a computer, and a plurality of binarized projection patterns can be applied to a measurement object under the control of the computer. A projector serving as a projecting unit for projecting, and a camera serving as an image capturing unit configured to include an imaging element such as a CCD that captures an image of a measurement object onto which a binary projection pattern is projected by the projector. Yes.

  That is, in the three-dimensional measuring apparatus, the projector is connected to a computer, and is arranged so that various binary projection patterns generated by the computer can be projected onto the surface of the measurement object. . Further, the camera is arranged so that the surface of the measurement object can be photographed from a direction different from the projection direction of the projector, and the image photographed by the camera is digitized and captured by the computer. Has been made.

  Then, the distance from the three-dimensional measuring device to the measurement object is measured by processing the image captured by the camera, digitized, and captured by the computer, and the surface of the measurement object is measured based on the distance thus measured. The three-dimensional shape is measured.

However, the surface color (hereinafter, the surface color of the measurement object is appropriately referred to as “surface color”) is black and white by the three-dimensional shape measuring apparatus using the spatial coding method as described above. When trying to measure a measurement object in which colors with large differences in luminance values are mixed, there is a problem that the shapes of the surfaces of all colors cannot be measured simultaneously. Hereinafter, this problem will be described with reference to the measurement object A in which black and white having a large difference in luminance values are mixed on the surface shown in FIG.

  When a binarized projection pattern is projected onto the measurement object A by a projector and the reflected light is captured by a camera, first, the binarized projection pattern in which the surface color such as white is projected onto a bright part In order to be able to obtain the difference in luminance, it is necessary to shorten the exposure time of the camera. However, when the exposure time of the camera is shortened, the brightness difference of the binarized projection pattern projected is hardly obtained at the black surface portion (see FIG. 3A), and as a result, the surface color is bright. Only the three-dimensional shape of the surface of the film could be measured (see FIG. 3B).

  On the other hand, in contrast to the above, it is necessary to lengthen the exposure time of the camera in order to obtain the luminance difference of the binarized projection pattern in which the surface color such as black is projected onto the dark part. . However, when the exposure time of the camera is lengthened, the binarized projection pattern projected on the portion where the surface is white causes halation and a luminance difference cannot be obtained (see FIG. 4A). As a result, the color of the surface It was a thing which can measure only the surface shape of a dark part (refer FIG.4 (b)).

  Note that the above-described problems are caused by the fact that the dynamic range of input light of the image sensor that constitutes the imaging means is narrower than that of the human eye.

The prior art that the applicant of the present application knows at the time of filing a patent is as described above and is not an invention related to a known literature, so there is no prior art information to be described.

  The present invention has been made in view of the various problems of the prior art as described above, and the object of the present invention is not to depend on the brightness or darkness of the color of the surface of the measurement object. An object of the present invention is to provide a three-dimensional shape measuring method and apparatus capable of measuring the shape of the entire surface of an object.

  In order to achieve the above object, according to the present invention, an imaging unit acquires reflected light images from a measurement object onto which the same binarized projection pattern is projected at different shutter speeds (exposure times). A spatial code image is obtained based on the acquired image.

  That is, in the present invention, for example, the following processes (1) to (4) are performed.

  (1) Shooting a plurality of images of the same binarized projection pattern projected with various exposure times.

  (2) One image (multiple shutter speed image) is generated by combining the plurality of captured images captured in (1) above. Thereby, the dynamic range of the image sensor can be virtually expanded, and the shape of the entire surface of the measurement object can be measured without depending on the brightness of the surface color of the measurement object.

  (3) In the spatial coding method, for example, a binary projection pattern for 8 bits is projected, and the processing of (1) and (2) is performed for each bit to obtain a multiple shutter speed image for 8 bits. Is generated.

  (4) Using the obtained 8-bit multiple shutter speed image, a spatial code image is generated in the same manner as the processing by the conventional spatial coding method, and the three-dimensional shape is restored based on the generated spatial code image. To do.

The invention according to claim 1 of the present invention captures a reflected light image from a measurement object projected with a binarized projection pattern, and generates a spatial code image using the captured reflected light image. In the three-dimensional shape measurement method for measuring the three-dimensional shape of the measurement object by a spatial encoding method, a predetermined binarized projection pattern, which is a stripe-shaped pattern including a light transmission region and a light non-transmission region, is described above. It shifts to the half phase inversion range where the position of the light transmission area and the light non-transmission area of the predetermined binarized projection pattern is switched, and becomes the minimum resolution regarding the measurement resolution of the three-dimensional shape measurement on the measurement object The projected images are sequentially projected onto the measurement object while shifting by a predetermined movement amount, and the reflected light image from the measurement object on which the predetermined binarized projection pattern is projected is shifted for each shift. A plurality of reflected light images captured at different shutter speeds (exposure times) for each shift, and a plurality of images captured at different shutter speeds (exposure times) for each shift. A multiple shutter speed image for each shift is generated by extracting effective pixels having a predetermined condition from a plurality of reflected light images and combining them into one by using the reflected light image, and multiple shutters for each shift A phase shift image obtained by synthesizing the speed image is generated, and a plurality of different types of binarized projection patterns including the predetermined binarized projection pattern are projected onto the measurement object, respectively. Reflected light images from the measurement object onto which the binary projection pattern is projected are converted into a plurality of different binary projection patterns. The effective pixels having a predetermined condition are extracted and synthesized from the reflected light images captured at different exposure times for each of the plurality of different types of binarized projection patterns. A multiple shutter speed image for each of a plurality of different binarized projection patterns is generated, a spatial code image is generated by combining the multiple shutter speed images for each of a plurality of different binarized projection patterns, and the phase shift image And the spatial code image are combined with each other to generate a phase shift spatial code image that is an absolute code value that has been optically resolved up to the shift pitch with respect to the imaging space, and the phase shifted spatial code image is converted into the spatial code image. By obtaining the three-dimensional shape of the measurement object based on the phase-shift space code image, Further, as a method of generating a multiple shutter speed image for each shift and a multiple shutter speed image for each of the plurality of different binarized projection patterns, the exposure time is applied to a black portion on the measurement object. The exposure time necessary for visually recognizing the binarized projection pattern is the longest exposure time, and the exposure time necessary for visually recognizing the binarized projection pattern hitting the white portion on the measurement object is the shortest exposure. A plurality of exposure times obtained by dividing a time that is the difference between the longest exposure time and the shortest exposure time into a plurality of equal intervals, and the reflected light image for brightness with each pixel, the value indicating the brightness of the visual and pixel value, the maximum brightness of the pixel having a predetermined condition image having By using the exposure time e at the time of shooting and the pixel value o of the pixel using a pixel having a value, a formula i = o / e values calculated from the removal of the influence of the pixel value by the exposure time determining a true brightness i, the logarithm scale (log 10 _(i)) with respect to calculated the true brightness value, by combining as a single image, and generates the multiplexed shutter speed image It is intended to be.

According to a second aspect of the present invention, in the above-described invention, the predetermined condition is that the upper limit pixel value is 240 to 250.

The invention according to claim 3 of the present invention captures a reflected light image from a measurement object projected with a binarized projection pattern, and generates a spatial code image using the captured reflected light image. In the three-dimensional shape measuring apparatus that measures the three-dimensional shape of the measurement object by the spatial encoding method, a predetermined binarized projection pattern that is a stripe-shaped pattern composed of a light transmission region and a light non-transmission region is obtained. Shifting to a half-phase inversion range where the positions of the light transmission region and the light non-transmission region of the predetermined binarized projection pattern are switched, and the minimum resolution regarding the measurement resolution of the three-dimensional shape measurement on the measurement object; Are sequentially projected onto the measurement object while shifting by a predetermined amount of movement, and the reflected light image from the measurement object onto which the predetermined binarized projection pattern is projected differs for each shift. To obtain a plurality of reflected light images taken at different shutter speeds (exposure times) for each shift, and to obtain a plurality of images taken at different shutter speeds (exposure times) for each shift. A multiple shutter speed image for each shift is generated by extracting effective pixels having a predetermined condition from a plurality of reflected light images and combining them into one by using the reflected light image, and multiple shutters for each shift A first means for generating a phase shift image obtained by synthesizing a speed image, and a plurality of different types of binarized projection patterns including the predetermined binarized projection pattern are respectively projected onto the measurement object; Reflected light images from the measurement object onto which a plurality of binarized projection patterns of different types are projected are binarized of different types. Images are captured with different exposure times for each shadow pattern, and effective pixels having a predetermined condition are extracted and synthesized from reflected light images captured with different exposure times for each of a plurality of different binary projection patterns. A multiple shutter speed image is generated for each of a plurality of different binarized projection patterns, and a spatial code image is generated by synthesizing the multiple shutter speed images for each of a plurality of different binarized projection patterns. And a synthesizing unit that generates a phase-shifted spatial code image that is an absolute code value that has been optically resolved to a shift pitch with respect to the imaging space, by synthesizing the phase-shifted image and the spatial code image. The measurement object based on the phase shift space code image by treating the phase shift space code image as a space code image. Three-dimensional shape acquisition means for acquiring a three-dimensional shape of the first and second means for generating a multiple shutter speed image for each shift, and a plurality of binary projections of different types. In each of the second means for generating a multiple shutter speed image for each pattern, the exposure time required for visually recognizing the binarized projection pattern hitting the black portion on the measurement object is the longest. The exposure time is set as the shortest exposure time, and the difference between the longest exposure time and the shortest exposure time is the exposure time necessary for visually recognizing the binarized projection pattern that hits the white portion on the measurement object. A plurality of exposure times obtained by dividing the time into a plurality of equal intervals are used, and for the reflected light image, each pixel included in the reflected light image has a bright light. For the, the value indicating the brightness of the visual and the pixel value, at the time of shooting and the pixel value o of the pixel using a pixel having a pixel value which is the maximum brightness among the pixels having the predetermined conditions Using the exposure time e, the value calculated from the formula i = o / e is determined as the true brightness i from which the influence of the exposure time on the pixel value is removed , and the calculated true brightness value A logarithmic scale (log ₁₀ (i)) is taken with respect to, and the multiple shutter speed images are generated by combining them as one image.

According to a fourth aspect of the present invention, in the above invention, the predetermined condition is that the upper limit pixel value is 240 to 250.

  Since the present invention is configured as described above, it is possible to measure the shape of the entire surface of the measurement object without depending on the brightness of the surface color of the measurement object. There is an effect.

  Hereinafter, an example of an embodiment of a three-dimensional shape measurement method and apparatus according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 5 is a schematic configuration explanatory diagram showing an example of an embodiment of a three-dimensional shape measuring apparatus according to the present invention.

  That is, the three-dimensional shape measuring apparatus 10 according to an example of the embodiment of the present invention includes a central processing unit (CPU) 12b connected via a bus 12a, and a read only memory (ROM) that stores programs executed by the CPU 12b. 12c, a random access memory (RAM) 12d as a working area in which a buffer memory for temporarily storing data signals and various registers necessary for executing a program by the CPU 12b are set, various input devices 12e such as a keyboard and a mouse, and the CPU 12b The overall operation of the computer 12 is controlled by a computer 12 having a display device 12f that outputs and displays the processing results of the above. Projection means for projecting a binarized projection pattern; Each of the projectors (projectors) 16 and an imaging device (camera) 18 as an imaging unit configured to include an imaging element that images the measurement target object 14 onto which the binarized projection pattern is projected by the projector 16. It is configured. In addition, as an image pick-up element, CCD, CMOS, etc. can be used, for example.

  In the three-dimensional shape measuring apparatus 10, the projector 16 is connected to the computer 12 and can project various binary projection patterns generated by the computer 12 onto the surface of the measurement object 14. Arranged so that you can. The photographing machine 18 is arranged so that the surface of the measuring object 14 can be photographed from a direction different from the projection direction of the projector 16, and the image photographed by the photographing machine 18 is digitized. Are taken into the computer 12.

  In the three-dimensional shape measuring apparatus 10, the photographing machine 18 captures reflected light images from the measurement object onto which the same binarized projection pattern is projected at different shutter speeds (exposure times). The computer 12 generates a single image (multiple shutter speed image) by synthesizing the plurality of captured images thus captured, and a spatial code image (described later) and a phase shift image (described later) based on the multiple shutter speed image. ).

  As the binarized projection pattern, a pattern similar to that described above with reference to FIGS. 1A, 1B, 1C, and 1D can be used. Description is omitted.

Next, FIG. 6 shows a block configuration explanatory diagram of a control system of the three-dimensional shape measuring apparatus 10 realized by the computer 12.

  The control system determines a plurality of binarized projection patterns to be used for the process of projecting by the projector 16, projects the determined binarized projection patterns onto the surface of the measurement object 14, and Binary projection for controlling to project any one of the determined binary projection patterns onto the surface of the measuring object 14 while shifting (moving) a predetermined movement amount in the width W direction. The pattern projection means 20, the image input means 22 that digitizes the image taken by the photographing machine 18 and sends it to the image processing means 24 (described later), and the image sent from the image input means 22 to process the measurement object 14 image processing means 24 for extracting three-dimensional information.

Here, the binarized projection pattern projection means 20 includes a binarized projection pattern generation unit 20a that generates a binarized projection pattern as shown in FIGS. 1A, 1B, 1C, and 2D, and 2 A binarized projection pattern projection control unit 20b that controls the projector 16 so as to project the binarized projection pattern generated by the binarized projection pattern generation unit 20a onto the measurement object 14 is configured. .

  That is, in the binarized projection pattern projecting means 20, the binarized projection pattern generation unit 20a generates a plurality of binarized projection patterns including a light transmission region 100a and a light non-transmission region 100b having a predetermined width W. To do.

  When a spatial code image generation process (described later) is performed, the binarized projection pattern projection control unit 20b controls the projector 16, and the types generated by the binarized projection pattern generation unit 20a are different. A plurality of binarized projection patterns are respectively projected onto the surface of the measurement object 14. At this time, the binarized projection pattern projection control unit 20b does not shift the binarized projection pattern projected onto the surface of the measurement object 14 in the width W direction.

  On the other hand, in the case of performing phase shift image generation processing (described later), the binarized projection pattern projection control unit 20b controls the projector 16, and a plurality of two generated by the binarized projection pattern generation unit 20a. Any one of the digitized projection patterns is projected onto the surface of the measurement object 14. At this time, the binarized projection pattern projection control unit 20b projects the binarized projection pattern projected onto the surface of the measurement object 14 while sequentially shifting the binarized projection pattern by a predetermined amount of movement in the width W direction.

  This amount of movement is arbitrary and may be smaller or larger than the width W, but this amount of movement becomes the minimum resolution regarding the measurement resolution of the shape measurement of the three-dimensional shape in the measurement object 14.

  Next, the image input unit 22 captures the binarized projection pattern projected on the surface of the measurement object 14 with the photographing machine 18, digitizes the image obtained by the photographing, and inputs the digitized image to the image processing unit 24. Is.

  At this time, the imaging device 18 captures images with different shutter speeds (exposure times) when capturing a reflected light image from a measurement object onto which a certain binarized projection pattern is projected, and the binarized projection pattern. It is possible to generate a multiple shutter speed image of the reflected light image from the measurement object projected.

  Furthermore, the image processing means 24 processes the image sent from the image input means 22 and extracts the three-dimensional information of the measurement object 14, and the types generated by the binarized projection pattern generation unit 20a are different. A plurality of binarized projection patterns are respectively projected onto the surface of the measurement object 14, and the surface of the measurement object 14 onto which the binarized projection pattern is projected by the photographing machine 18 is a plurality of binary projections of different types. An image captured at a different shutter speed (exposure time) for each pattern is sent from the image input means 22, and a single image (multiple images) obtained by synthesizing the sent images for each of a plurality of different types of binarized projection patterns. A shutter speed image) is generated, and an image obtained by combining multiple shutter speed images generated for each of a plurality of different binary projection patterns (hereinafter referred to as “spatial code image”). The space code image generation unit 24a that performs space code image processing and the binarized projection pattern generation unit 20a generate any one of the binarized projection patterns in the width W direction. The surface of the measurement object 14 projected onto the surface of the measurement object 14 while being sequentially shifted by the amount of movement, and the binarized projection pattern projected by the photographing machine 18 is different in shutter speed (exposure time) for each shift. Is sent from the image input means 22 to generate one image (multiple shutter speed image) obtained by synthesizing the sent image for each shift, and the multiple shutter speed image generated for each shift is generated. Phase shift image generation means 24b for performing phase shift image generation processing for generating a combined image (hereinafter referred to as “phase shift image” as appropriate). A phase shift spatial code image that is an image obtained by synthesizing the spatial code image (spatial code value) obtained by the spatial code image generation means 24a and the phase shift image (shift code value) obtained by the phase shift image generation means 24b is obtained. A phase shift space code image generation means 24c to be generated, and a 3D shape information acquisition means 24d for obtaining 3D shape information of the measurement object 14 from the phase shift space code image obtained by the phase shift space code image generation means 24c. It is configured.

  The three-dimensional shape information of the measurement object 14 acquired by the three-dimensional shape information acquisition unit 24d is output to the display device 12f and the like for use.

  Since the phase shift space code image, which is the image obtained by the phase shift space code image generation means 24c, is a space code image, the three-dimensional shape information acquisition means 24d can measure the measurement object without changing the space coding algorithm. 14 three-dimensional shape information can be acquired. In other words, the three-dimensional shape information acquisition unit 24d can be constructed by a conventionally known technique, and three-dimensional shape information can be obtained using a conventionally known technique.

In the above configuration, the operation of the three-dimensional shape measuring apparatus 10 will be described with reference to the flowchart shown in FIG.

  That is, in order to obtain the three-dimensional shape information of the measurement object 14 in the three-dimensional shape measuring apparatus 10, first, a plurality of binarized projection patterns having different predetermined widths W are generated in order to code the space. (Step S702).

Here, if the number of slits for dividing the space is n, log ₂ n different binary projection patterns must be prepared.

  Next, any one of the binarized projection patterns generated in step S702 is selected, and phase shift image generation processing for generating a phase shift image is performed (step S704). In other words, the selected binarized projection pattern is projected onto the surface of the measuring object 14 by the projector 16 while being sequentially shifted by a predetermined movement amount in the width W direction, and the binarized projection pattern is projected by the photographing machine 18. An image obtained by photographing the surface of the measured object 14 with a different shutter speed (exposure time) for each shift is sent from the image input means 22, and one image obtained by synthesizing the sent images for each shift. A multiple shutter speed image is generated, and a phase shift image is generated by combining the multiple shutter speed images generated for each shift.

  That is, in the phase shift image generation process, any one of the binarized projection patterns necessary for the spatial code image generation process described later is selected and used, and the binary used in this phase shift image generation process The normalized projection pattern is appropriately referred to as a “shift pattern”.

  As a shift pattern, any binarized projection pattern may be used in principle, and any binarized projection pattern can obtain the same effect. However, the width W is the largest in consideration of the number of shifts. It is preferable to use a narrow binarized projection pattern, that is, an LSB pattern.

  That is, in principle, any binary projection pattern can be used as the shift pattern. However, in the phase shift image generation process, a binary projection pattern is projected for each shift. In order to capture the image of the measured object 14, it is preferable to shift it using the LSB pattern that minimizes the number of captured images, in other words, minimizes the number of shifts.

  Further, the amount of movement for each shift when shifting the shift pattern (hereinafter referred to as “shift pitch” as appropriate) may be the pitch of the measurement resolution desired by the user of the measurement apparatus 10, and this shift pitch is the minimum resolution. It becomes. If the minimum dot pitch of the projector 16 is adopted, the measurement resolution can be maximized without being affected by the resolution of the projector 16.

  The shift pattern is shifted a plurality of times within one cycle of the pattern. That is, the shift width of the shift pattern is shifted to, for example, a range in which the phase of the LSB pattern is inverted by half phase in which the positions of the light transmission region 100a and the light non-transmission region 100b are switched.

  Here, when a phase shift image is generated by synthesizing multiple shutter speed images generated by photographing the surface of the measurement object 14 for each shift, each multiple shutter speed image generated for each shift is weighted. By adding them without (or even with the same weight), a phase shift image as a spatial code image having a minimum resolution of the shift pitch is generated.

  In the phase shift image, code values are repeated at a width W interval that is a stripe width interval of the binarized projection pattern, and a plurality of the same code values exist in the generated phase shift image. For this reason, in the phase shift image generation process, an absolute code value is not generated for the imaging space.

  Further, as will be described later, when a “gray code” is adopted for the binarized projection pattern, it is desirable to perform a bit calculation before adding.

  When the process of step S704 is completed, the process proceeds to step S706, and a spatial code image for generating a spatial code image using a plurality of binary projection patterns having different predetermined widths W generated in step S702 is used. Perform the generation process. That is, the projector 16 projects a plurality of different types of binarized projection patterns onto the surface of the measurement object 14, and the surface of the measurement object 14 onto which the binarized projection pattern is projected by the photographing machine 18, Images taken at different shutter speeds (exposure times) for each of a plurality of different types of binarized projection patterns are sent from the image input means 22 and sent for each of a plurality of different types of binarized projection patterns. A multiple shutter speed image, which is one image obtained by combining the images, is generated, and a spatial code image is generated by combining the multiple shutter speed images generated for each of the plurality of different types of binarized projection patterns.

  That is, in the spatial code image generation process, for example, if an LSB pattern is selected as the shift pattern, a binary projection pattern including the LSB pattern before the shift is projected onto the surface of the measurement object 14 and each 2 A multiple shutter speed image of a binarized projection pattern is generated, and a so-called spatial code image is generated by a conventionally known method of generating a spatial code image using the multiple shutter speed images of each binarized projection pattern. To do.

  The resolution of the space code image is the stripe width of the LSB pattern, but is an absolute code for the shooting space.

  Next, a phase shift spatial code image generation process for generating a phase shift spatial code image by synthesizing the phase shift image generated in step S704 and the spatial code image generated in step S706 is performed (step S708). This phase-shift space code image is a combination of a phase-shift image that is an image with a code value relative to the shooting space and a space code image that is an image with an absolute code value with respect to the shooting space. The generated phase shift space code image is an image having a shift pitch as a measurement resolution and an absolute code value with respect to the imaging space. That is, an absolute code image (code value) subdivided (high resolution) up to the shift pitch is generated.

  When the process of step S708 ends, the process proceeds to step S710, and a three-dimensional shape information acquisition process for acquiring the three-dimensional shape information of the measurement object 14 is performed based on the phase shift space code image generated in step S708. . That is, since the phase shift space code image is a space code image, the phase shift space code image is treated as a space code image, and the three-dimensional shape information of the measurement object 14 is obtained using a conventionally known technique.

  Then, the three-dimensional shape information of the measurement object 14 acquired by the three-dimensional shape information acquisition process in step S710 is output to the display device 12f and the like for various uses.

Next, the principle of a technique for photographing a binarized projection pattern image projected onto the surface of the measurement object 14 for each shift while shifting the shift pattern will be described in more detail below.

  First, in FIGS. 8A, 8B, and 8C, the light non-transmissive region (the region indicated by hatching in FIGS. 8A, 8B, and 8C) has a 16-divided shift pitch width on the left side in the figure. Each shift when shifting the shift pattern from right to right and shifting to a position where the light transmission region (the region not hatched in FIGS. 8A, 8B, and 8C) and the light non-transmission region are reversed. The pattern shift state and the code value corresponding to each shift pitch are shown. In FIGS. 8A, 8B, and 8C, black 1 to n indicate how many times the light non-transmission region includes the shift pattern by shifting the shift pattern.

  Here, FIG. 8A divides the image into a space with the shift pitch as the resolution, and the binarized image of the shift pattern and the same pixel in each image captured for each shift. Divide the space by simply adding values.

  For example, as shown in FIG. 8B, if the shift pattern is divided into two in advance, the number of shifts is halved, and both the number of shots and the shooting time are halved.

  Similarly, as shown in FIG. 8 (c), if the shift pattern is divided into four, the number of shifts becomes ¼, and if further divided, the number of shifts similarly decreases, and the number of shots and the shooting time also increase. It can be shortened.

  For this reason, as the shift pattern, it is more efficient to select the LSB pattern having the smallest stripe width among the binarized projection patterns, that is, the number of divisions.

In addition, as shown in FIGS. 8B and 8C, the phase shift image includes code values that are repeated at intervals of the width W of the stripes of the binarized projection pattern. There will be multiple identical code values. For this reason, an absolute code value is not generated for the shooting space.

  However, the same code value obtained by shifting the shift pattern has a feature that it does not occur a plurality of times in the binarized values of the light transmission region and the light non-transmission region of the shift pattern.

  For example, in FIG. 8C, when the pattern divided into four by the binarized projection pattern “light non-transmission area | light transmission area | light non-transmission area | light transmission area” is used as the shift pattern, “black 1 "Has occurred in four places.

  However, only one place occurs in the “light transmission region” in the shift pattern. Similarly, there is only one code value “black 1” in the “light non-transmission region” in the shift pattern.

  Here, when a binary code pattern including a shift pattern before shifting is projected and photographed to generate a spatial code image, the resolution of the spatial code image is the stripe width of the LSB pattern, Absolute code value.

  That is, as shown in FIG. 9, the imaging space is uniquely coded such that “right light transmitting area” of the shift pattern is “space code 0” and “left light non-transmitting area” is “space code 3”. it can.

  Therefore, as shown in FIG. 10, a composition by adding together a phase shift image having a code value relative to the imaging space and a space code image having an absolute code value is not required. Thus, it is possible to generate a phase shift space code image having a shift pitch as a resolution and an absolute code value with respect to the imaging space.

  Thereby, for example, when the space is divided into 16, the number of shifts can be reduced without performing 16 shifts, and the number of shots and the shooting time can be shortened.

In the above description, the case where a binary code is used has been described. However, the principle is the same for a commonly used gray code.

  Here, FIG. 11 shows the result of processing the phase-shift space code image using a known spreadsheet software using the binarized projection pattern expressed by the Gray code.

  In FIG. 11, the light transmission area is represented by “1”, the light non-transmission area is represented by “0”, and the space code value is actually up to 255, but only up to 35 is displayed.

  Further, since the resolution of the projector is shifted assuming that it is four times the stripe width of the LSB pattern in the binarized projection pattern, the shift is four times if it is a binary code, but it is 7 because it is a gray code. It has been shifted times.

  G32 to G1 indicate binarized projection patterns expressed in gray code, and S1 to S7 indicate patterns obtained by phase shifting G1 (LSB).

  In the list of addition, a value obtained by simply adding the phase shift is shown. Here, the phase shift image that has been added must change from “0 to 3”, but the size and direction of change are not constant, “0 to 7” and “7 to 0”. .

  Although it can be combined with the spatial code image as it is, the calculation at the time of extracting the three-dimensional information becomes complicated. Therefore, by performing the Bit calculation shown in FIG. The direction of change is indicated by a value that matches the spatial code image generated from the binary code.

  The conversion data list shows values obtained by converting the G32 to G1 gray code patterns into binary code patterns. The binary spatial code indicates a spatial code image generated from the binary code.

  As shown in FIG. 13, the phase shift spatial code image obtained by synthesizing the phase shift image converted from the gray code to the binary code by the bit operation and the spatial code image generated from the binary code has a staircase graph as shown in FIG. In contrast to the spatial code image generated from the binary code, the phase shift spatial code image shows that the slope of the graph is linear and the resolution is improved.

The above-described three-dimensional shape measuring apparatus 10 does not require a special configuration other than the function of shifting the shift pattern and the function of synthesizing the phase-shifted image and the spatial code image, and is used in the conventional spatial coding method. , A high-resolution spatial code image can be generated only by synthesizing the photographed image, thereby improving the resolution of the three-dimensional shape measurement of the measurement object 14.

  In the above-described three-dimensional shape measuring apparatus 10, the measurement resolution depends on the shift pitch and is independent of the stripe width W of the binarized projection pattern. Depending on the resolution of the machine 16 or the camera 18, the width of the LSB pattern can be identified.

Next, the point that the reflected light image from the measurement object onto which the same binarized projection pattern is projected by the camera 18 is captured at different shutter speeds (exposure times) will be described.

  Here, an imaging device such as a CMOS or a CCD constituting the photographing device 18 has a narrow dynamic range with respect to input light as compared with the human eye. Therefore, in the image sensor, if the light sensitivity is adjusted to recognize the brightness difference in the bright part, the dark part cannot be recognized, and the light sensitivity is adjusted to recognize the brightness difference in the dark part. Then, the bright part could not be recognized.

Therefore, images are taken with various light sensitivities, and pixels capable of recognizing a binarized projection pattern (slit pattern) are extracted from these images and combined into a single image. Then, from this image, it becomes possible to recognize the slit pattern in the entire region regardless of the luminance difference on the object surface. This means that the dynamic range related to the amount of incident light energy in the image sensor is virtually expanded.
As a method of changing the sensitivity of the image pickup device, there are a method of adjusting the aperture of the lens and a method of adjusting the shutter speed (time for accumulating charges in the image pickup device). Here, in the method of adjusting the aperture of the lens, it is preferable to adopt a method of adjusting the shutter speed because the depth of field changes and affects the degree of blur of the captured image.

  Then, effective pixels are extracted from the image taken while performing such adjustment and combined into one. Note that an image obtained by extracting effective pixels from images taken at a plurality of shutter speeds and combining them into one is generally referred to as a “multiple shutter speed image” as described above. Academic Media Center, Kyoto University, “Multifunctional high-precision image measurement by integrating multiple images”, Media Information Processing Course “Computer Vision (Basics of Image Measurement and 3D Shape Restoration)” Seminar Materials / Practice Materials, May 2005 ”and Reference 2 “Takaji Matsuyama, Yoshinori Kuno, Satoshi Imiya,“ Computer Vision (Technical Review and Future Prospects) ”, New Technology Communications, 1998”).

Next, details of a method for generating a multiple shutter speed image by imaging the reflected light image from the measurement object onto which the same binarized projection pattern is projected at different shutter speeds (exposure time) by the camera 18 will be described. To do.

First, the relationship between exposure time, pixel value (apparent brightness), and true brightness will be described (see Document 1).

  At certain points in the captured image, the pixel value increases as the exposure time increases. That is, within the dynamic range of the image sensor, the relationship between the exposure time and the pixel value is linear. Specifically, referring to FIG. 14, for example, if the pixel value when the exposure time is 2 msec is 128, if the exposure time is 1 msec, which is half of 2 msec, the pixel value is half as 64. Get dark.

  That is, if the exposure time is e, and the pixel value at a certain point in the image taken at the exposure time e is o (the pixel value o takes a value from 0 to 255), the pixel value o. The value i (= o / e) divided by the exposure time value e when the image is taken is constant regardless of the exposure time. In the present specification, i obtained as described above is referred to as “true brightness” from which the influence of the exposure time on the pixel value is removed.

Here, the selection criterion for true brightness will be described. When the energy of light incident on the image sensor exceeds the dynamic range, the pixel value o on the captured image exceeds 255 or falls below 0. . Even if the true brightness is calculated using the pixel value in that case as described above, a correct value cannot be obtained. In general, pixel values of captured images include the following characteristics (a) to (d) (see Document 1).

(A) The influence of noise is large when the signal level during shooting is low. (B) The linearity of input and output is disturbed when the signal level during shooting is high. (C) The signal level during shooting is saturated (> 255) The data that is being used cannot be used. (D) The shorter the exposure time, the lower the accuracy.

In this embodiment, based on the characteristics described above, the true brightness is determined by the algorithm shown in the following (1) to (4), and a plurality of pixels having the true brightness are set as effective pixels. Are extracted from an image photographed at a shutter speed, and the extracted pixels are combined as one image to generate a multiple shutter speed image. As a matter of course, since the image is synthesized using the extracted effective pixels, the effective pixels are extracted for all the pixels of the photographed image.

(1) The upper limit of the effective range of pixel values, that is, the upper limit pixel value is set. Generally, the upper limit of the effective range of pixel values, that is, the upper limit pixel value is about 240 to 250 from the above (b) and (c). However, in this embodiment, it is “250”.
(2) The lower limit of the effective range of the pixel luminance value, that is, the lower limit pixel value is set. In this embodiment, the lower limit pixel value is set to “5”.
(3) The pixel having the maximum pixel value within the range defined in the above (1) and (2) is adopted, and the true brightness is obtained by i = o / e from the pixel value o and the exposure time e at the time of photographing. Determine i,
(4) If the pixel value exceeds the upper limit pixel value for the photographed images at all exposure times, it means that the upper limit pixel value has been exceeded even at the shortest exposure time. The value obtained by “value / shortest exposure time” is adopted.
On the other hand, if the pixel value is lower than the lower limit pixel value for the captured images at all exposure times, this means that the longest exposure time is below the lower limit pixel value. Adopt the value obtained by “/ longest exposure time”.
Thereby, as the true brightness i, a value close to the true brightness normally obtained near the upper limit pixel value or the lower limit pixel value can be obtained.
As a result, the brightness change near the upper limit pixel value or the lower limit pixel value becomes smooth.

Next, a method of visualizing the true brightness will be described. In the above-described algorithms (1) to (4), the exposure time at that time becomes shorter as the true brightness basically increases. Here, since the accuracy of the pixel value becomes worse as the exposure time becomes shorter, the accuracy becomes worse as the true brightness increases. Therefore, a logarithmic scale (log ₁₀ (i)) is taken with respect to the true brightness value obtained above, and this is imaged. Specifically, for example, pixel values may be calculated for all coordinate pixels, and scaled so that the minimum value is 0 and the maximum value is 255.

Next, application of an image obtained by projecting an actual binarized projection pattern (slit pattern) will be described.

  First, a reflected light image from a measurement object onto which the same binarized projection pattern is projected is photographed at different shutter speeds, that is, with different exposure times.

  Here, when imaging a measurement object in which black and white are mixed as surface colors, the user actually binarizes the projection pattern so as to satisfy the following conditions (a) to (e): The pattern of the exposure time is set by looking at the state of the reflected light image of the projection.

(A) The longest exposure time is set so that the slit pattern hitting the black part can be visually recognized.
(B) The exposure time that can visually recognize the slit pattern that hits the white part is the shortest exposure time.
(C) The exposure time is set in about 2 to 3 steps at equal time intervals between the value of the longest exposure time and the value of the shortest exposure time obtained in (a) and (b) above.
(D) For all these exposure times, project a slit pattern and take a reflected image of the projection.
(E) Using the reflected light image taken in (d) above, calculate the true brightness of each pixel of each reflected light image by the method described above, and use the images taken at multiple shutter speeds. Effective pixels are extracted, and the extracted images are combined into one to generate a multiple shutter speed image.

Here, when the true brightness is calculated and the maximum value and the minimum value are obtained, it is performed through a positive / negative complementary pattern of the same spatial code. The purpose of the spatial coding method is to generate a binary image from the luminance difference between the positive and negative patterns of the slit (Ref. 3 “Seiji Iguchi, Kosuke Sato,“ Three-dimensional image measurement ”, Shosodo, 1990). To be able to generate it accurately.

  If the maximum and minimum values of true brightness are obtained separately for positive and negative, they will be different, and the range scaled by the process of visualizing the true brightness will also be different. Then, for example, in a pixel where the positive image is originally brighter and the negative image is darker, the relationship may be reversed. In such a case, an accurate binary image cannot be obtained.

  For this reason, it is necessary to match the reference luminance of the positive / negative image of the same bit made from the true brightness.

Next, the experimental results of the present inventor will be described. FIGS. 15A, 15B, 15C, and 15D show images actually taken.

  That is, in FIGS. 15A, 15B, 15C, and 15D, the exposure time is 40 msec (FIG. 15A), 27.3 msec (FIG. 15B), and 14.7 msec (FIG. 15C). )) As shown in 2 msec (FIG. 15 (d)), an image is shown that is taken while changing from 40 msec to 2 msec at four equal intervals. FIG. 16 shows a multiple shutter speed image synthesized from them.

  In the image shown in FIG. 15A, which has the longest exposure time, the brightness difference of the slit pattern can be recognized when the surface color of the measurement object is black, but it is overexposed when the surface color of the measurement object is white. Wake up and cannot recognize. On the contrary, in the image shown in FIG. 15D where the exposure time is the shortest, the slit pattern can be recognized when the surface color of the measurement object is white, but the portion where the surface color of the measurement object is black is crushed and recognized. Can not.

  However, in the multiple shutter speed image shown in FIG. 16, the slit pattern crushed in FIGS. 15A and 15D also clearly appears.

  Here, when generating the multiple shutter speed image shown in FIG. 16, four exposure time patterns shown in FIGS. 15A, 15B, 15C, and 15D, that is, 4 patterns are used as the exposure pattern. However, an experiment was conducted to examine the optimal number of patterns.

  In FIG. 17A, two patterns of the longest 40 msec and the shortest 2 msec are used as the exposure patterns, and the image shown in FIG. 15A with an exposure time of 40 msec and the image shown in FIG. 15D with an exposure time of 2 msec. A multiple shutter speed image generated using only and is shown. On the other hand, in FIG. 17B, four patterns of 40 msec, 27.3 msec, 14.7 msec, and 2 msec are used as exposure patterns, and the images shown in FIGS. 15A, 15B, 15C, and 15D are used. A multiple shutter speed image generated in this manner is shown.

  When the multiple shutter speed image shown in FIG. 17A is compared with the multiple shutter speed image shown in FIG. 17B, the multiple shutter speed image shown in FIG. It can be seen that there is a portion where the change in brightness is discontinuous at some places.

  The reason for this is that, except for the image with the longest exposure time at the time of image composition, except for the pixels whose luminance exceeds the upper limit, the next adopted image is not the image with the intermediate exposure time, but suddenly the image with the shortest exposure time. This is because the continuity between the synthesized pixels is deteriorated.

  If there is a possibility that an unnecessary luminance difference occurs in this way, the result may be inaccurate when a necessary binary image is generated by the spatial coding method based on the image. It is desirable to avoid using only two patterns.

  Next, FIG. 18A shows an image (shading display) showing a three-dimensional shape restoration result when the number of exposure patterns is 2, and FIG. 18B shows a case where the number of exposure patterns is 3. FIG. 18C shows an image (shading display) showing the three-dimensional shape restoration result when the number of exposure patterns is four. FIG. 18D shows an image (shading display) showing a three-dimensional shape restoration result when the number of exposure patterns is five.

  Comparing the three-dimensional shape restoration results shown in FIGS. 18A, 18B, 18C, and 18D, when the number of exposure patterns is 2 or 3, the number of exposure patterns is 4 as compared to the case of 4 patterns. There is a part where the shape is slightly missing, such as the part indicated by the arrow. Further, when the number of exposure patterns was 5, no visual difference was seen compared to the case where the number of exposure patterns was 4.

  Therefore, in the case described above, it is preferable to perform photographing with at least four exposure patterns.

As described above, by photographing the projection image of the binarized projection pattern with a plurality of exposure time patterns and synthesizing these images, a color having a large difference in luminance value is mixed on the surface of the measurement object. Even in this case, the luminance difference of the slit pattern can be obtained over the entire image, and as a result, a stable measurement result that does not depend on the luminance difference of the surface color of the measurement object can be obtained.

  Here, FIGS. 19A and 19B show the three-dimensional shape restoration results when the multiple shutter speed image is not used, and FIG. 19A shows the case where the image is taken with a short exposure time. FIG. 19B shows the three-dimensional shape restoration result when an image is taken with a long exposure time. On the other hand, FIG. 19C shows a three-dimensional shape restoration result when a multiple shutter speed image according to the present invention is used.

  Comparing the three-dimensional shape restoration results shown in FIGS. 19 (a), 19 (b), and 19 (c), FIGS. 19 (a) and 19 (b) except for portions that cannot be originally captured due to blind spots or the like. It can be seen that the shape of the portion that could not be restored in () was restored.

The embodiment described above may be modified as described in the following (1) to (4).

  (1) In the above embodiment, the phase shift spatial coding method is used as the spatial coding method. However, the present invention is not limited to this, and a conventionally known spatial coding method may be used. In this case as well, it is sufficient to obtain a spatial code image using a multiple shutter speed image.

  (2) In the above-described embodiment, the spatial code image generation process is performed after the phase shift image generation process. However, the present invention is not limited to this, and the order of both processes is not limited. Conversely, the phase code image generation processing may be performed after the spatial code image generation processing.

  (3) In the above-described embodiment, the binarized projection pattern is generated. However, the present invention is not limited to this, and a plurality of binarizations having different widths W are stored in the storage means. The projection pattern may be stored in advance, and the binarized projection pattern stored in the storage unit may be read as appropriate.

  (4) You may make it combine the above-mentioned embodiment and the modification shown in said (1) thru | or (3) suitably.

  The present invention can be used for shape acquisition in industrial design, human body shape acquisition, or building shape acquisition.

1A, 1B, 1C, and 1D are explanatory diagrams showing examples of various binarized projection patterns. FIG. 2 is an explanatory diagram illustrating an example of a measurement object in which black and white having a large difference in luminance value are mixed on the surface. FIGS. 3A and 3B are explanatory diagrams when the exposure time of the camera is short, and FIG. 3A shows the measurement object shown in FIG. 2 onto which the binarized projection pattern is projected. It is explanatory drawing of the reflected light image at the time of imaging with a short camera, FIG.3 (b) is an image which shows the measurement result of the three-dimensional shape obtained using the reflected light image shown to Fig.3 (a). FIGS. 4A and 4B are explanatory diagrams when the exposure time of the camera is long. FIG. 4A shows the measurement object shown in FIG. 2 onto which the binarized projection pattern is projected. It is explanatory drawing of the reflected light image at the time of imaging with a long camera, FIG.4 (b) is an image which shows the measurement result of the three-dimensional shape obtained using the reflected light image shown to Fig.4 (a). FIG. 5 is a schematic configuration explanatory diagram showing an example of an embodiment of a three-dimensional shape measuring apparatus according to the present invention. FIG. 6 is a block diagram for explaining the control system of the three-dimensional shape measuring apparatus according to the present invention. FIG. 7 is a flowchart showing the operation of the three-dimensional shape measuring apparatus according to the present invention. FIGS. 8A, 8B and 8C are explanatory views showing the operating principle of the three-dimensional shape measuring apparatus according to the present invention. FIG. 9 is an explanatory diagram showing the operation principle of the three-dimensional shape measuring apparatus according to the present invention. FIG. 10 is an explanatory diagram showing the operation principle of the three-dimensional shape measuring apparatus according to the present invention. FIG. 11 is a table showing a result of processing a phase shift space code image using a known spreadsheet software using a binarized projection pattern expressed in Gray code. FIG. 12 shows the calculation contents of the Bit calculation. FIG. 13 is a graph showing a phase-shifted spatial code image obtained by synthesizing a phase-shifted image converted from a Gray code to a binary code by a Bit operation and a spatial code image generated from the binary code. FIG. 14 is an explanatory diagram showing the relationship between exposure time, pixel value (apparent brightness), and true brightness. FIGS. 15A, 15B, 15C, and 15D are images (8-bit space codes) showing the results of experiments by the inventors of the present application. FIG. 16 is a multiple shutter speed image synthesized from the images shown in FIGS. 15 (a), (b), (c), and (d). 17A uses two patterns of the longest 40 msec and the shortest 2 msec as the exposure pattern, and the image shown in FIG. 15A with an exposure time of 40 msec and the image shown in FIG. 15D with an exposure time of 2 msec. FIG. 17B uses four patterns of 40 msec, 27.3 msec, 14.7 msec, and 2 msec as exposure patterns, and FIG. (A) (b) (c) It is the multiple shutter speed image (all projection image) produced | generated using the image shown to (d). FIG. 18A is an image (shading display) showing a three-dimensional shape restoration result when the number of exposure patterns is two, and FIG. 18B shows a three-dimensional shape restoration result when the number of exposure patterns is three. FIG. 18C is an image (shading display) showing a three-dimensional shape restoration result when the number of exposure patterns is 4. FIG. 18D is a case where the number of exposure patterns is 5. It is an image (shading display) which shows the three-dimensional shape restoration result. FIGS. 19A and 19B show a three-dimensional shape restoration result (texture mapping display) when a multiple shutter speed image is not used, and FIG. 19A shows a case where an image is taken with a short exposure time. FIG. 19B shows a three-dimensional shape restoration result (texture mapping display) when an image is taken with a long exposure time. FIG. 19C shows a three-dimensional shape restoration result (texture mapping display). The three-dimensional shape restoration result (texture mapping display) at the time of using the multiple shutter speed image by invention is shown.

Explanation of symbols

10 Three-dimensional shape measuring device 12 Computer 12a Bus 12b Central processing unit (CPU)
12c Read only memory (ROM)
12d random access memory (RAM)
12e Input device 12f Display device 14 Measurement object 16 Projector 18 Camera 20 Binary projection pattern projection unit 20a Binary projection pattern generation unit 20b Binary projection pattern projection control unit 22 Image input unit 24 Image processing unit 24a Spatial code Image generation means 24b Phase shift image generation means 24c Phase shift space code image generation means 24d Three-dimensional shape information acquisition means A Measurement object

Claims (4)

A reflected light image from the measurement object projected with the binarized projection pattern is imaged, and a three-dimensional shape of the measurement object is obtained by a spatial coding method that generates a spatial code image using the captured reflected light image. In the three-dimensional shape measuring method for measuring,
A predetermined binarized projection pattern which is a stripe-shaped pattern composed of a light transmissive region and a light non-transparent region is replaced with a position where the light transmissive region and the light non-transmissive region of the predetermined binarized projection pattern are switched. Shifting to a range where two phases are reversed, and sequentially projecting on the measurement object while shifting by a predetermined movement amount that becomes the minimum resolution regarding the measurement resolution of the three-dimensional shape measurement in the measurement object, the predetermined 2 A reflected light image from the measurement object onto which the digitized projection pattern is projected is captured at different shutter speeds (exposure times) for each shift, and a plurality of reflections are captured at different shutter speeds (exposure times) for each shift. Using a plurality of reflected light images acquired at different shutter speeds (exposure times) for each shift, a predetermined condition is obtained from the plurality of reflected light images. Generating a multiple shutter speed image of each said shift by combining into one by extracting effective pixels, to generate a phase-shifted images obtained by combining the multiple shutter speed image of each said shift,
The measurement in which a plurality of different binarized projection patterns including the predetermined binarized projection pattern are respectively projected onto the measurement object, and the plurality of different types of binarized projection patterns are projected. Reflected light images from an object are captured at different exposure times for each of the plurality of different types of binarized projection patterns, and reflected at different exposure times for the different types of binarized projection patterns. Extracting and synthesizing effective pixels having a predetermined condition from the light image to generate multiple shutter speed images for each of the plurality of different types of binarized projection patterns, and a plurality of different types of binarized projections Generate a spatial code image that combines multiple shutter speed images for each pattern,
By synthesizing the phase shift image and the space code image, a phase shift space code image that is an absolute code value that has been optically resolved to a shift pitch with respect to the imaging space is generated,
By treating the phase shift space code image as a space code image, the three-dimensional shape of the measurement object is obtained based on the phase shift space code image,
further,
As a method of generating a multiple shutter speed image for each shift and a multiple shutter speed image for each of the plurality of different binarized projection patterns,
Regarding the exposure time, the exposure time necessary for visually recognizing the binarized projection pattern hitting the black part on the measurement object is the longest exposure time, and the binarization hitting the white part on the measurement object The exposure time necessary for visually recognizing the projection pattern is set as the shortest exposure time, and a plurality of exposure times obtained by dividing the time that is the difference between the longest exposure time and the shortest exposure time into a plurality of equal intervals are used. Shall be
As for the brightness of each pixel included in the reflected light image, the value indicating the apparent brightness is set as a pixel value, and the pixel value that is the maximum brightness among the pixels having the predetermined condition is set as the reflected light image. A true value obtained by removing the influence of the exposure time on the pixel value from the value calculated by the calculation formula i = o / e using the pixel value o of the pixel and the exposure time e at the time of shooting. Determined as brightness i,
The multiple shutter speed image is generated by taking a logarithmic scale (log ₁₀ (i)) with respect to the calculated true brightness value and combining them as one image. Dimensional shape measurement method. The three-dimensional shape measuring method according to claim 1,
The predetermined condition is that the upper limit pixel value is 240 to 250.
A three-dimensional shape measuring method characterized by the above. A reflected light image from the measurement object projected with the binarized projection pattern is imaged, and a three-dimensional shape of the measurement object is obtained by a spatial coding method that generates a spatial code image using the captured reflected light image. In a three-dimensional shape measuring apparatus for measuring,
A predetermined binarized projection pattern which is a stripe-shaped pattern composed of a light transmissive region and a light non-transparent region is replaced with a position where the light transmissive region and the light non-transmissive region of the predetermined binarized projection pattern are switched. Shifting to a range where two phases are reversed, and sequentially projecting on the measurement object while shifting by a predetermined movement amount that becomes the minimum resolution regarding the measurement resolution of the three-dimensional shape measurement in the measurement object, the predetermined 2 A reflected light image from the measurement object onto which the digitized projection pattern is projected is captured at different shutter speeds (exposure times) for each shift, and a plurality of reflections are captured at different shutter speeds (exposure times) for each shift. Using a plurality of reflected light images acquired at different shutter speeds (exposure times) for each shift, a predetermined condition is obtained from the plurality of reflected light images. First means for generating a multiple shutter speed image of each said shift generates a phase shift image obtained by synthesizing the multiple shutter speed image of each said shift by combining into one by extracting valid pixels,
The measurement in which a plurality of different binarized projection patterns including the predetermined binarized projection pattern are respectively projected onto the measurement object, and the plurality of different types of binarized projection patterns are projected. Reflected light images from an object are captured at different exposure times for each of the plurality of different types of binarized projection patterns, and reflected at different exposure times for the different types of binarized projection patterns. Extracting and synthesizing effective pixels having a predetermined condition from the light image to generate multiple shutter speed images for each of the plurality of different types of binarized projection patterns, and a plurality of different types of binarized projections A second means for generating a spatial code image obtained by combining multiple shutter speed images for each pattern;
Combining means for generating a phase-shifted spatial code image that is an absolute code value that has been optically resolved to a shift pitch with respect to the imaging space by combining the phase-shifted image and the spatial code image;
3D shape acquisition means for acquiring the 3D shape of the measurement object based on the phase shift space code image by treating the phase shift space code image as a space code image,
further,
In each of the first means for generating a multiple shutter speed image for each shift and the second means for generating a multiple shutter speed image for each of the plurality of different binarized projection patterns,
Regarding the exposure time, the exposure time necessary for visually recognizing the binarized projection pattern that hits the black portion on the measurement object is the longest exposure time, and the binarization that hits the white portion on the measurement object The exposure time necessary for visually recognizing the projection pattern is set as the shortest exposure time, and a plurality of exposure times obtained by dividing the time that is the difference between the longest exposure time and the shortest exposure time into a plurality of equal intervals are used. Shall be
As for the brightness of each pixel included in the reflected light image, the value indicating the apparent brightness is set as a pixel value, and the pixel value that is the maximum brightness among the pixels having the predetermined condition is set as the reflected light image. A true value obtained by removing the influence of the exposure time on the pixel value from the value calculated by the calculation formula i = o / e using the pixel value o of the pixel and the exposure time e at the time of shooting. Determined as brightness i,
The multiple shutter speed image is generated by taking a logarithmic scale (log ₁₀ (i)) with respect to the calculated true brightness value and combining them as one image. Dimensional shape measuring device. The three-dimensional shape measuring apparatus according to claim 3,
The predetermined condition is that the upper limit pixel value is 240 to 250.
A three-dimensional shape measuring apparatus.