JP4944435B2 - 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 particularly, a method for measuring a three-dimensional shape using a spatial coding method for generating an absolute code value for a space by a binary projection pattern. And to the device.

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

  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 is a method of projecting a plurality of binary projection patterns, which are striped light patterns composed of a light transmission region and a light non-transmission region, onto a measurement object, thereby forming the stripe shape. When one point on the measurement object projected with the light pattern is observed, the light beam projected onto the one point being observed blinks to form a code. This is a technique of measuring the three-dimensional shape of a measurement object using a code.

  In this spatial coding 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 ray is known 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 this allows the three-dimensional measurement object to be measured. The shape can be measured in a non-contact manner.

  By the way, it is known that the measurement resolution of a three-dimensional shape in the above-described spatial coding method depends on the width of the stripe pattern.

  Therefore, in the spatial encoding method, the measurement resolution improves as the width of the stripe-shaped pattern is reduced. However, as the width of the stripe-shaped pattern is reduced, the intensity of light on the light projecting side is increased. It is difficult to identify the stripe pattern on the light receiving side due to irregular reflection at the imaging space and the measurement object, and there is a limit to narrowing the width of the stripe pattern.

  In other words, the spatial coding method has a limit on the segmentation of the code due to the influence of the resolution of the projector and the photographing machine and the shape and surface state of the measurement object, and the measurement resolution of the three-dimensional shape cannot be made so fine. The problem was pointed out.

Therefore, as a technique for solving the problems of the spatial coding method described above, for example, a technique combining the spatial coding method and the multi-slit image encoder method is disclosed in Japanese Patent Application Laid-Open No. 2005-3409. Proposed in the Gazette.

  In the method disclosed in Japanese Patent Laid-Open No. 2005-3409, a projector connected to a computer is used to first project a multi-slit pattern onto a measurement object and photograph the image, and then use the same projector. Thus, a plurality of stripe patterns coded so that the absolute position of the space can be identified by a combination of the brightness and darkness of the stripes are sequentially projected.

  At that time, the projection pattern is photographed with a camera from a direction different from the projection direction, and an image corresponding to each projection pattern is obtained.

  Here, according to the projection patterns of the multi-slit pattern and the stripe pattern, the respective projection images will be referred to as the multi-slit projection image and the stripe projection image, respectively. A change in brightness over time is checked, and a relative projection angle image is generated with the relative projection position (projection angle) of the slit at the timing when the pixel exhibits the maximum luminance as the value of the pixel.

  Based on the triangulation principle, the precise partial shape of the region corresponding to the minimum width of the stripe pattern is calculated from the value of each pixel of the relative projection angle image and the geometric relationship between the pattern projection means and the imaging means. Ask.

  On the other hand, with respect to the stripe projection image, the temporal change in the brightness of each pixel is checked for each pixel, and coding is performed using a stripe pattern. For example, the sequence of the light and dark changes is encoded to create an absolute projection angle image having the pixel value.

  In this way, each pixel is associated with the minimum width stripe indicated by the code, that is, the zone of the projection angle.

  Then, based on the triangulation principle from the geometric relationship between the value of each pixel (projection angle) of the absolute projection angle image, pattern projection means, imaging means, and target reference plane (coordinate system for shape calculation). This is obtained by calculating the shape of the stripe projected on the surface of the measurement object.

  Therefore, according to the technique disclosed in Japanese Patent Application Laid-Open No. 2005-3409, a rough overall shape with the minimum stripe width can be obtained.

However, in the technique disclosed in the above Japanese Patent Application Laid-Open No. 2005-3409, that is, a technique that combines the spatial coding method and the multi-slit image encoder method, the imaging space can be multi-coded by the spatial coding method that can recognize the absolute shape. The same n-division as the slit (n-coding), and high-resolution 3D shape recognition is made possible by synthesizing high-resolution data using the multi-slit image encoder method for each division. In addition to this system, there is a problem that a complicated configuration such as a slit generation function, a peak detection and holding function, a projection angle storage function, or an angle / time conversion function for configuring a multi-slit image encoder is required. It was.

Furthermore, in order to process such a complicated configuration, there is a problem that a burden on a control system such as a central processing unit (CPU) increases and a long time is required for processing.
Japanese Patent Laid-Open No. 2005-3409

  The present invention has been made in view of the various problems of the conventional techniques as described above, and an object thereof is to improve the measurement resolution of shape measurement of a three-dimensional shape with a simple configuration. It is an object of the present invention to provide a method and apparatus for measuring a three-dimensional shape that can be used.

  In order to achieve the above object, the present invention provides a binarized projection pattern that is not affected by the resolution, that is, a binarized projection pattern that does not reach the limit of the width of the stripe pattern. The spatial code is subdivided by shifting.

  That is, the present invention uses a spatial coding method for generating an absolute code value for a space by a binarized projection pattern, and shifts the binarized projection pattern by an arbitrary amount of movement, thereby achieving high measurement resolution. It is something that can be obtained.

  According to the present invention, since the algorithm of the spatial coding method can be used as it is, the hardware and software configurations can be used as they are, and the three-dimensional configuration can be achieved with a simple configuration. The measurement resolution of shape measurement can be improved.

Among these aspects of the invention, the invention according to claim 1 projects the binarized projection pattern onto the measurement object, and based on the image of the measurement object onto which the binarized projection pattern is projected, the measurement object In a three-dimensional shape measuring method for measuring a three-dimensional shape of an object, the width of the stripe-shaped pattern does not reach the limit of fineness and is configured to have a predetermined stripe shape that is not affected by the resolution . A predetermined amount of movement that shifts the binarized projection pattern to a range in which the phase of the predetermined binarized projection pattern is inverted by a half phase in which the positions of the light transmission region and the light non-transmission region are switched , and Projecting sequentially onto the measurement object while shifting a plurality of times within one cycle of the predetermined binarized projection pattern, and photographing the surface of the measurement object onto which the predetermined binarized projection pattern is projected at each shift did The first type of images acquired as the phase shift code values by combining the images of all, including the predetermined binary projection pattern, the plurality of binarized projection pattern having a width of different patterns respectively Each time each of the plurality of different binarized projection patterns is projected onto the measurement object and each of the different binarized projection patterns is projected, the surface of the measurement object on which the different binarized projection patterns are projected is photographed. All images are combined to obtain a second type of image as a first spatial code value , the first type of image and the second type of image are combined, and the first spatial code A third type of image is acquired as a second spatial code value that is subdivided from the value, and the three-dimensional shape of the measurement object is acquired using the second spatial code value. is there.

  According to a second aspect of the present invention, in the first aspect of the present invention, the binarized projection pattern has a predetermined width and is perpendicular to the width direction. Light transmitting regions and light non-transmitting regions extending in the direction are formed alternately and continuously in a stripe shape.

  The invention according to claim 3 of the present invention is the invention according to claim 2 of the present invention, wherein the direction of shifting the predetermined binarized projection pattern with respect to the object to be measured is This is the width direction.

  According to a fourth aspect of the present invention, in the invention according to any one of the second or third aspects of the present invention, the predetermined binarized projection pattern includes a plurality of different pluralities. The binarized projection pattern has the narrowest width among the binarized projection patterns.

The invention according to claim 5 of the present invention projects the binarized projection pattern onto the measurement object, and measures the measurement based on the image of the measurement object onto which the binary projection pattern is projected. In a three-dimensional shape measuring apparatus for measuring the three-dimensional shape of an object, a predetermined stripe shape whose width does not reach the limit of thinness and is not affected by the resolution is predetermined. A predetermined amount of movement that shifts the binarized projection pattern to a range in which the phase of the light-transmitting region and the light non-transmitting region of the predetermined binarized projection pattern is reversed by a half phase , and The surface of the measurement object onto which the predetermined binarized projection pattern is projected at each shift is sequentially projected onto the measurement object while shifting a plurality of times within one cycle of the predetermined binarized projection pattern. I took a picture By combining the images of Te comprises a first image acquiring means for acquiring a first type of image as a phase shift code value, the predetermined binary projection pattern, the plurality having a width of different patterns respectively 2 The measurement object in which each of the plurality of different binarized projection patterns is projected each time the binarized projection pattern is projected onto the measurement object and each of the plurality of different binarized projection patterns is projected. A second image acquisition unit that combines all images obtained by photographing the surface of the object to acquire a second type of image as a first spatial code value; and the second image acquisition unit acquired by the first image acquisition unit. 1 type of image and the second image acquiring unit is acquired by the above second type of an image synthesizing, and the second space code value subdivided than the first spatial code value Synthesizing means for obtaining a third type of image, based on the second spatial code value is synthetic result synthesized by the synthesizing means, three-dimensional shape acquiring for acquiring a three-dimensional shape of the measurement object Means.

The invention according to claim 6 of the present invention is the invention according to claim 5 of the present invention, wherein the binarized projection pattern has a predetermined width and is perpendicular to the width direction. Light transmitting regions and light non-transmitting regions extending in the direction are formed alternately and continuously in a stripe shape.

The invention described in claim 7 of the present invention is the invention described in claim 6 of the present invention, wherein the direction in which the predetermined binarized projection pattern is shifted with respect to the object to be measured is This is the width direction.

Further, the invention according to claim 8 of the present invention is the invention according to any one of claims 6 or 7 in the present invention, wherein the predetermined binarized projection pattern has a plurality of different ones. The binarized projection pattern has the narrowest width among the binarized projection patterns.

  Since the present invention is configured as described above, there is an excellent effect that the measurement resolution of the shape measurement of the three-dimensional shape can be improved with a simple configuration.

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

FIG. 1 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, a three-dimensional shape measuring apparatus (hereinafter simply referred to as “measuring apparatus” as appropriate) 10 according to an example of an embodiment of the present invention includes a central processing unit (CPU) 12b connected via a bus 12a, A read only memory (ROM) 12c storing a program executed by the CPU 12b, a buffer memory for temporarily storing data signals, and a random access memory (RAM) as a working area in which various registers necessary for executing a program by the CPU 12b are set. ) 12d, which is configured to control the overall operation by a computer 12 having various input devices 12e such as a keyboard and a mouse and a display device 12f that outputs and displays the processing results of the CPU 12b. To the measuring object 14 under the control of the computer 12 A projector 16 for projecting a binary projection pattern number, is configured to include an imaging device 18 for photographing a measuring object 14 by the projector 16 is projected binarization projection pattern.

  That is, in the measuring apparatus 10, the projector 16 is connected to the computer 12 and is arranged so that various binary projection patterns generated by the computer 12 can be projected onto the surface of the measurement object 14. Has been. 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.

Here, FIGS. 2A, 2B, 2C, and 2D show examples of various binary projection patterns generated by the computer 12. FIG.

  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. 2A, 2B, 2C, and 2D, the binarized projection pattern having the narrowest width W is as 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.

Next, FIG. 3 shows a block configuration explanatory diagram of a control system of the 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 projecting means 20 includes a binarized projection pattern generation unit 20a that generates a binarized projection pattern as shown in FIG. 2 and 2 generated by the binarized projection pattern generation unit 20a. A binarized projection pattern projection control unit 20b that controls the projector 16 so as to project the binarized projection pattern 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.

  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 for each pattern is sent from the image input means 22, and a spatial code for performing spatial code image processing for generating an image obtained by synthesizing the sent image (hereinafter referred to as "spatial code image" as appropriate). The measuring object 1 while sequentially shifting any one of the binarized projection patterns generated by the image generating unit 24a and the binarized projection pattern generating unit 20a by a predetermined amount of movement in the width W direction. An image obtained by photographing the surface of the measuring object 14 onto which the binary projection pattern is projected by the photographing device 18 is sent from the image input means 22 and the sent images are synthesized. Phase shift image generation means 24b for performing phase shift image generation processing for generating an image (hereinafter referred to as "phase shift image" as appropriate), and a 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, a phase shift space code image generation means 24c for generating a phase shift space code image as an image, and a phase shift space code image generation 3D shape information acquisition means for obtaining 3D shape information of the measurement object 14 from the phase shift space code image obtained by the means 24c It is configured to have a 4d.

  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 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 measurement apparatus 10, first, in order to code the space, a plurality of binarized projection patterns having different predetermined widths W are generated (steps). S402).

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 S402 is selected, and phase shift image generation processing for generating a phase shift image is performed (step S404). 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 for each shift is sent from the image input means 22, and the sent images are combined to generate a phase shift image.

  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-shifted image is generated by synthesizing images obtained by capturing the surface of the measurement object 14 for each shift, each image captured for each shift may be weighted (or may have the same weight). .) By adding, a phase-shifted image that is 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 S404 is completed, the process proceeds to step S406, 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 S402. 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 for each of the plurality of different binarized projection patterns are sent from the image input means 22, and the sent images are combined to generate a spatial code image.

  That is, in the spatial code image generation process, for example, if an LSB pattern is selected as a shift pattern, a binarized projection pattern including the LSB pattern before the shift is projected onto the surface of the measurement object 14. A known so-called spatial code image is generated.

  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 combining the phase shift image generated in step S404 and the spatial code image generated in step S406 is performed (step S408). 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 S408 is completed, the process proceeds to the process of step S410, and a three-dimensional shape information acquisition process for acquiring the three-dimensional shape information of the measurement object 14 based on the phase shift space code image generated in step S408. Do. 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 S410 is output to the display device 12f and the like for use in various ways.

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. 5A, 5B, and 5C, the light non-transmission region (the region indicated by hatching in FIG. 5) is obtained by shifting the shift pattern from the left side to the right side with a shift pitch width divided into 16 parts. The shift state of each shift pattern and the code value corresponding to each shift pitch when the light transmission region (the non-hatched region in FIG. 5) and the light non-transmission region are shifted to the reverse position are shown. Yes. In FIGS. 5A, 5B, and 5C, black 1 to n indicate how many times the light non-transmission region includes the shift pattern by shifting the shift pattern.

  Here, FIG. 5A 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. 5B, if the shift pattern is divided into two in advance, the number of shifts is halved, and the number of shots and the shooting time are both halved.

  Similarly, as shown in FIG. 5C, if the shift pattern is divided into four, the number of shifts is reduced to ¼, and if further divided, the number of shots is reduced and the shooting time is shortened. Can do.

  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. 5B and 5C, 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. 5C, 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 spatial code image has a resolution of the stripe width of the LSB pattern. Absolute code value.

  That is, as shown in FIG. 6, the shooting space is uniquely coded such that “right light transmissive area” of the shift pattern is “space code 0” and “left light non-transmissive area” is “space code 3”. it can.

  Therefore, as shown in FIG. 7, 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.

  As a result, for example, when the space is divided into 16, the number of shots can be reduced without performing 16 shifts or shooting, 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. 8 shows the result of processing a phase shift space code image using a known spreadsheet software using a binarized projection pattern expressed in Gray code.

  In FIG. 8, 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. 10, 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 measuring apparatus 10 uses the configuration used in the conventional spatial coding method without requiring any special configuration other than the function of shifting the shift pattern and the function of synthesizing the phase shift image and the spatial code image. Thus, a high-resolution spatial code image can be generated only by synthesizing the photographed image, whereby the resolution of the three-dimensional shape measurement of the measurement object 14 can be improved.

  In the measurement apparatus 10 described above, 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 camera 18, the width of the LSB pattern stripes can be identified.

The embodiment described above may be modified as described in the following (1) to (3).

  (1) 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.

  (2) 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.

  (3) You may make it combine the above-mentioned embodiment and the modification shown in said (1) thru | or (2) suitably.

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

FIG. 1 is a schematic configuration explanatory diagram showing an example of an embodiment of a three-dimensional shape measuring apparatus according to the present invention. 2A, 2B, 2C, and 2D are explanatory diagrams showing examples of various binarized projection patterns. FIG. 3 is a block diagram illustrating the control system of the three-dimensional shape measuring apparatus according to the present invention. FIG. 4 is a flowchart showing the operation of the three-dimensional shape measuring apparatus according to the present invention. 5 (a), 5 (b), and 5 (c) are explanatory views showing the operation principle of the three-dimensional shape measuring apparatus according to the present invention. FIG. 6 is an explanatory diagram showing the operating principle of the three-dimensional shape measuring apparatus according to the present invention. FIG. 7 is an explanatory diagram showing the operating principle of the three-dimensional shape measuring apparatus according to the present invention. FIG. 8 is a table showing the result of processing a phase-shift space code image using a known spreadsheet software using a binary projection pattern expressed in Gray code. FIG. 9 shows the calculation contents of the Bit calculation. FIG. 10 is a graph showing a phase shift spatial code image obtained by synthesizing a phase shift image converted from a Gray code to a binary code by a Bit operation and a spatial code image generated from the binary code.

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 spatial code image generation means 24d Three-dimensional shape information acquisition means

Claims (8)

A three-dimensional shape measuring method for projecting a binary projection pattern onto a measurement object and measuring a three-dimensional shape of the measurement object based on an image of the measurement object onto which the binary projection pattern is projected In
A predetermined binarized projection pattern having a stripe shape whose width does not reach the thinness limit and is not affected by the resolution is used as the predetermined binarized projection pattern. Shifting a plurality of times within a predetermined period of the predetermined binarized projection pattern with a predetermined movement amount that shifts to a half-phase inversion range where the positions of the light transmitting region and the light non-transmitting region are switched. Then, the first type of image is phase- synthesized by combining all images obtained by sequentially projecting onto the measurement object and photographing the surface of the measurement object on which the predetermined binarized projection pattern is projected for each shift. As a shift code value ,
A plurality of binarized projection patterns each having a different pattern width including the predetermined binarized projection pattern are respectively projected onto the measurement object, and each of the plurality of different binarized projection patterns is projected. For each, a second type of image is obtained as a first spatial code value by synthesizing all images obtained by imaging the surface of the measurement object onto which the plurality of different binary projection patterns are projected. ,
Synthesizing the first type image and the second type image, obtaining a third type image as a second spatial code value subdivided from the first spatial code value; The three-dimensional shape measurement method, wherein the three-dimensional shape of the measurement object is acquired using the second spatial code value . The method for measuring a three-dimensional shape according to claim 1,
The binarized projection pattern is a pattern in which a light transmission region and a light non-transmission region having a certain width and extending in a predetermined direction orthogonal to the width direction are alternately formed in a stripe shape. A method for measuring a three-dimensional shape. The three-dimensional shape measuring method according to claim 2,
The method of measuring a three-dimensional shape, wherein a direction in which the predetermined binarized projection pattern is shifted with respect to the measurement object is the width direction. In the measuring method of the three-dimensional shape of any one of Claim 2 or 3,
The three-dimensional shape measuring method, wherein the predetermined binarized projection pattern is a binarized projection pattern having the narrowest width among the plurality of different binarized projection patterns. A three-dimensional shape measuring apparatus that projects a binarized projection pattern onto a measurement object and measures the three-dimensional shape of the measurement object based on the image of the measurement object onto which the binary projection pattern is projected. In
A predetermined binarized projection pattern having a stripe shape whose width does not reach the thinness limit and is not affected by the resolution is used as the predetermined binarized projection pattern. Shifting a plurality of times within a predetermined period of the predetermined binarized projection pattern with a predetermined movement amount that shifts to a half-phase inversion range where the positions of the light transmitting region and the light non-transmitting region are switched. Then, the first type of image is phase- synthesized by combining all images obtained by sequentially projecting onto the measurement object and photographing the surface of the measurement object on which the predetermined binarized projection pattern is projected for each shift. First image acquisition means for acquiring a shift code value ;
A plurality of binarized projection patterns each having a different pattern width including the predetermined binarized projection pattern are respectively projected onto the measurement object, and each of the plurality of different binarized projection patterns is projected. Each time, a second type of image is obtained as a first spatial code value by synthesizing all images obtained by photographing the surface of the measurement object onto which the plurality of different binary projection patterns are projected. A second image acquisition means;
The first type of image acquired by the first image acquisition unit and the second type of image acquired by the second image acquisition unit are combined, and from the first spatial code value Combining means for obtaining a third type of image as a second spatial code value that is also subdivided ;
Three-dimensional shape acquisition means for acquiring a three-dimensional shape of the measurement object based on the second spatial code value which is a synthesis result synthesized by the synthesis means. measuring device. The three-dimensional shape measuring apparatus according to claim 5 ,
The binarized projection pattern is a pattern in which a light transmission region and a light non-transmission region having a certain width and extending in a predetermined direction orthogonal to the width direction are alternately formed in a stripe shape. A three-dimensional shape measuring apparatus. The three-dimensional shape measuring apparatus according to claim 6 ,
The direction in which the predetermined binarized projection pattern is shifted with respect to the measurement object is the width direction. The three-dimensional shape measuring apparatus according to any one of claims 6 and 7 ,
The three-dimensional shape measuring apparatus, wherein the predetermined binarized projection pattern is a binarized projection pattern having the narrowest width among the plurality of different binarized projection patterns.

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