JP6247724B2 - Measuring device - Google Patents

Description

  The present invention relates to a measurement device, a control method for the measurement device, and a program.

  Several methods have been proposed as a three-dimensional shape measurement method used in a three-dimensional shape measurement apparatus. There are known a passive method in which shape measurement is performed only by an imaging device without using a projection device, and an active method in which a projection device and an imaging device are used in combination. In the active method, the three-dimensional shape of an object is measured from an image obtained by photographing the projected object. Since the object has a three-dimensional shape, the three-dimensional shape measurement apparatus is required to satisfy the accuracy necessary for shape measurement in the depth direction.

  Patent Documents 1 and 2 are disclosed as examples of such an active three-dimensional shape measuring apparatus. Patent Document 1 discloses a technique for irradiating an object with a slit-like projection, controlling the light source so that the integrated irradiation intensity distribution has a triangular wave shape, and performing three-dimensional shape measurement using the principle of the phase shift method. Has been. Patent Document 2 discloses a technique for making a sine wave pattern by defocusing a projection pattern of digital gradation values and performing three-dimensional shape measurement using the principle of the phase shift method as in Patent Document 1. .

Japanese Patent Laid-Open No. 11-118443 JP 2007-85862 A

  However, in the three-dimensional shape measuring apparatus described in Patent Document 1, it is difficult to satisfy the required accuracy in the entire depth direction of the object on the measurement reference plane. Similarly, in the three-dimensional shape measuring apparatus described in Patent Document 2, it is difficult to satisfy the required accuracy in the entire area in the depth direction of the object. This is because an image obtained by photographing an object is deteriorated in contrast with defocusing from the focus surface of the photographing optical system, and the accuracy of the three-dimensional shape calculated from the image having deteriorated contrast is deteriorated.

  Specifically, when the measurement reference plane is the focus plane of the photographing optical system as in Patent Document 1, the contrast of the photographed image decreases as the object placed on the measurement reference plane moves away from the measurement reference plane. Measurement accuracy deteriorates. For this reason, there is a problem that the measurement accuracy on the surface closest to the photographing apparatus is greatly deteriorated with respect to the measurement accuracy of the object on the measurement reference surface, and it is difficult to satisfy the required accuracy in the entire region in the depth direction.

  Further, as in Patent Document 2, when the focus surface of the projection pattern is outside the region where the object exists, the contrast of the projection pattern is directed toward a surface far from the surface of the object close to the focus surface of the projection pattern. descend. As a result, the contrast of the captured image is lowered, so that the measurement accuracy is deteriorated, and there is a problem that it is difficult to satisfy the necessary accuracy in the entire area in the depth direction as in Patent Document 1.

  In view of the above-described problems, an object of the present invention is to suppress a decrease in measurement accuracy in the depth direction and obtain good measurement accuracy in the entire measurement space.

The measuring device according to the present invention that achieves the above object is as follows.
Projection means for projecting a pattern including a bright part and a dark part onto an object;
Imaging means for imaging the object while a pattern is projected by the projection means;
Detecting means for detecting an edge position indicating a boundary between a bright part and a dark part of the pattern from an image picked up by the image pickup means;
Measuring means for measuring the three-dimensional shape of the object based on the detected edge position;
The focal position of the imaging means is a measurement including a position determined based on an axis passing through the center position of the projection range of the projection means and an axis passing through the center position of the imaging range of the imaging means when viewed from the imaging means. It is set behind the reference plane,
The focal position of the projection means is set on the measurement reference plane ,
The contrast value between the bright part and the dark part in the image has a maximum value in a region deeper than the measurement reference plane .

  According to the present invention, it is possible to suppress a decrease in measurement accuracy in the depth direction and to obtain good measurement accuracy in the entire measurement space.

The lineblock diagram of the three-dimensional shape measuring device concerning a 1st embodiment. The figure which shows the measurement reference plane and measurement space which concern on 1st Embodiment. The figure which shows the projection pattern which concerns on 1st Embodiment. 1 is a schematic diagram of an optical system according to a first embodiment. 1 is a schematic diagram of an optical system according to a first embodiment. The block diagram of the three-dimensional shape measuring apparatus which concerns on 2nd Embodiment. The figure which shows the measurement reference plane and measurement space which concern on 2nd Embodiment. The schematic diagram of the optical system which concerns on 2nd Embodiment. The schematic diagram of the optical system which concerns on 2nd Embodiment. The block diagram of the three-dimensional shape measuring apparatus which concerns on 3rd Embodiment. The figure which shows the measurement reference plane and measurement space which concern on 3rd Embodiment. The schematic diagram of the optical system which concerns on 3rd Embodiment. The figure which shows the relationship between the shooting distance and contrast which concern on 1st Embodiment, or the relationship between a shooting distance and the brightness of a picked-up image. The figure which shows the relationship between the imaging distance which concerns on 1st Embodiment, and a measurement error.

(First embodiment)
With reference to FIG. 1, the structure of the three-dimensional shape measuring apparatus according to the first embodiment will be described. The three-dimensional shape measurement apparatus includes a projection unit 101, an imaging unit 102, and a control unit 103.

  The projection unit 101 is a projector that performs a projection operation of projecting pattern light onto the object 104. The projection unit 101 can project into the space indicated by the projection range 105. Assume that the projection unit 101 does not coincide with the projection axis and the center of the projection image, like a projector used for upward projection in a conference room or the like. Here, the projection axis is an optical axis toward the projection center.

  The imaging unit 102 is a camera that captures an object 104 onto which pattern light is projected. The photographing unit 102 can photograph the space indicated by the photographing range 106. The control unit 103 is a personal computer, for example, and controls operations of the projection unit 101 and the photographing unit 102. The control unit 103 also executes processing for measuring the three-dimensional shape of the object 104.

  Next, the measurement reference plane and the measurement space according to the first embodiment will be described with reference to FIG. The optical axis 107 is an optical axis from the projection unit 101 toward the center of the projection image, and does not coincide with the projection axis. The optical axis 108 is the optical axis of the imaging unit 102 (imaging axis toward the imaging center). The measurement reference plane 109 is a plane including a point where the optical axis 107 and the optical axis 108 intersect. The measurement space 110 is a space that is included in both the projection range 105 and the imaging range 106 and is defined by the projection range 105 and the imaging range 106. In the present embodiment, the measurement reference plane 109 is included in the measurement space, and is arranged so as to bisect the depth direction distance of the measurement space 110 when observed from the imaging unit 102. The measurement surface 116 is the measurement surface closest to the projection unit 101 and the imaging unit 102 in the measurement space 110. The measurement surface 117 is the measurement surface farthest from the projection unit 101 and the imaging unit 102 in the measurement space 110. In the present embodiment, the measurement reference plane 109 is set inside the measurement space 110, but is not necessarily limited to the inside and may be outside.

  The three-dimensional shape measurement apparatus according to the present embodiment performs shape measurement by a spatial encoding method. First, the projection unit 101 projects a light and dark pattern 111 as shown in FIG. Then, the photographing unit 102 photographs the object 104 on which the light and dark pattern 111 is projected. The control unit 103 processes the image photographed by the photographing unit 102 and measures the three-dimensional shape of the object 104. More specifically, the light / dark edge position of the light / dark pattern 111 is detected, and projection is performed based on the principle of triangulation based on the angle formed by the projection axis of the projection unit 101 and the imaging axis of the imaging unit 102 corresponding to the edge position. The distance from the part 101 and the photographing part 102 to the object 104 is calculated.

  In the present embodiment, a negative / positive intersection detection method is used as a method for detecting the edge position of the light / dark pattern 111. The negative / positive intersection detection method is a method in which the projection unit 101 continuously projects a pattern in which the light / dark position of the light / dark pattern 111 is switched, and the intersection of the intensity distribution of the image captured by the image capturing unit 102 is used as the edge position.

  In the negative / positive intersection detection method, it is generally known that the higher the contrast of a light and dark pattern photographed by the photographing unit 102, the higher the edge position detection accuracy. Further, the SN (ratio of signal to noise) of the photographing unit 102 is improved when the brightness of the image photographed by the photographing unit 102 is high. Therefore, the projection from the projection unit 101 has higher edge position detection accuracy when the brightness is higher.

  In the three-dimensional shape measurement apparatus according to the present embodiment, it is necessary to measure the shape with a precision higher than necessary over the entire measurement space 110. However, as shown in FIG. 13A, the image captured by the imaging unit 102 has a high contrast at the focus position, but the contrast decreases when the image deviates from the focus position. Further, as shown in FIG. 13B, when the distance from the photographing unit 102 is short, the capture angle becomes large and the image becomes bright, but when the distance from the photographing unit 102 is long, the capture angle becomes small and the image becomes small. Becomes darker.

  Therefore, when the focus position of the photographing unit 102 is set to the measurement reference surface 109, the contrast on the measurement surface 116 decreases due to defocusing, but the photographed image is bright because the measurement surface 116 is close to the photographing unit 102. On the other hand, on the measurement surface 117, the contrast is reduced due to defocusing, and the captured image is also dark because the measurement surface 117 is far from the imaging unit 102. Therefore, the relationship between the shooting distance and the measurement error is as shown in FIG. 14A, and the measurement accuracy on the measurement surface 117 is lower than that on the measurement surface 116.

  Therefore, in the present embodiment, the focus position of the projection unit 101 is adjusted to the measurement reference plane 109, and the focus position of the imaging unit 102 is adjusted from the imaging unit 102 to the back side of the measurement reference plane 109.

  FIG. 4 shows the state of the focus position of the projection unit 101. The lens 112 schematically represents the projection optical system of the projection unit 101 as a single lens, and the display element 113 displays a light / dark pattern. As shown in FIG. 4, the focus position of the projection unit 101 is aligned with the measurement reference plane 109.

  On the other hand, FIG. 5 shows a state of the focus position of the photographing unit 102. The lens 114 schematically represents the photographing optical system of the photographing unit 102 as one lens, and the photographing element 115 converts the light that has entered from the lens 114 into an electrical signal. As shown in FIG. 5, the focus position of the photographing unit 102 is set to the back side with respect to the measurement reference plane 109.

  With the configuration shown in FIGS. 4 and 5, as shown in FIG. 13C, the contrast reduction due to the defocus of the imaging unit 102 on the measurement surface 116 is caused by the contrast reduction on the measurement surface 117. Bigger than. Accordingly, the relationship between the shooting distance and the measurement error is as shown in FIG. 14B, and when combined with the change in brightness of the shot image according to the distance from the shooting unit 102, the measurement accuracy of the measurement surface 116 is measured. The measurement accuracy of the measurement surface 117 is about the same. In addition, since the focus position of the photographing unit 102 is behind the measurement reference plane 109, the reduction in contrast on the measurement plane 117 is smaller than when the focus position is on the measurement reference plane 109. Therefore, the measurement accuracy on the measurement surface 117 is improved as compared with the case where the focus position is on the measurement reference surface 109. That is, the measurement error is within a certain range over the entire photographing distance, and the accuracy is not drastically reduced, and a certain measurement accuracy can be obtained as a whole.

  As described above, by setting the focus position of the photographing unit 102 behind the measurement reference plane 109, it is possible to obtain a certain measurement accuracy in the entire measurement space 110. When the focus position of the photographing unit 102 is set to the measurement reference plane 109, in order to obtain the same measurement accuracy as the present embodiment in the entire measurement space 110, the imaging performance of the photographing unit 102 is increased and the contrast of the photographed image is increased. Or the amount of light projected from the projection unit 101 needs to be increased. However, since this is not necessary in the present embodiment, it is not necessary to increase the imaging performance of the photographing unit 102 more than necessary, and the number of lenses constituting the photographing unit 102 can be reduced, leading to cost reduction as a whole. In addition, by reducing the output of the light source of the projection unit 101, the power consumption is reduced, and the heat generated from the light source is reduced, so that the cooling system can be made smaller, leading to miniaturization.

  Here, when the depth of the measurement space is large and the distance between the measurement surface 116 and the measurement surface 117 is further away, the difference between the brightness of the captured image on the measurement surface 116 and the brightness of the captured image on the measurement surface 117 is larger. Therefore, the focus position of the photographing unit 102 is set to a position closer to the measurement surface 117. As a result, a decrease in contrast due to defocus on the measurement surface 117 is reduced, and a decrease in accuracy on the measurement surface 117 can be further reduced.

  When the contrast reduction due to the defocus of the lens 114 of the photographing unit 102 is large, the focus position of the photographing unit 102 is set to a position close to the measurement reference plane 109. As a result, a decrease in contrast due to defocus on the measurement surface 116 is reduced, and a decrease in accuracy on the measurement surface 116 can be further reduced.

  Note that, as a method of adjusting the focus position of the photographing unit 102 behind the measurement reference plane 109, the focus position may be set behind the measurement reference plane 109 when designing the photographing optical system of the photographing unit 102. Further, when the photographing unit 102 has an autofocus function, a focus adjustment chart is arranged by placing a focus adjustment chart at a position to be focused, or focus adjustment is performed after focusing on the measurement reference plane 109. A method of focusing on the back side using a special lens may be used. In addition, when the focus position is too deep, a portion where the measurement accuracy is lowered appears. Therefore, the focus position may be set to an appropriate position depending on the relationship between the contrast and the brightness of the image.

  In this embodiment, three-dimensional shape measurement is performed by a spatial encoding method, and a negative / positive intersection detection method is used as a method for detecting an edge position. However, the method is not limited to the negative / positive intersection detection method, and a method of detecting an edge position using a differential filter or detecting the center of gravity of an intensity distribution may be used. Further, the three-dimensional shape measurement method is not limited to the spatial encoding method, and a phase shift method or a light cutting method for projecting a sine wave pattern may be used.

(Second Embodiment)
With reference to FIG. 6, the structure of the three-dimensional shape measuring apparatus which concerns on 2nd Embodiment is demonstrated. The three-dimensional shape measurement apparatus includes a projection unit 201, an imaging unit 202, and a control unit 203.

  The projection unit 201 is a projector that performs a projection operation of projecting pattern light onto the object 204. The projection unit 201 can project into the space indicated by the projection range 205. Unlike the first embodiment, the projection unit 201 assumes that the projection axis coincides with the center of the projection image.

  The imaging unit 202 is a camera that captures an object 204 onto which pattern light is projected. The photographing unit 202 can photograph the space indicated by the photographing range 206. The control unit 203 is a personal computer, for example, and controls operations of the projection unit 201 and the imaging unit 202. The control unit 203 also executes processing for measuring the three-dimensional shape of the object 204.

  Next, a measurement reference plane and a measurement space according to the second embodiment will be described with reference to FIG. The optical axis 207 is an optical axis from the projection unit 201 toward the center of the projection image, and coincides with the projection axis. An optical axis 208 is an optical axis of the imaging unit 202 (imaging axis toward the imaging center). The measurement reference plane 209 is a plane including a point where the optical axis 207 and the optical axis 208 intersect. The measurement space 210 is a space that is included in both the projection range 205 and the imaging range 206 and is defined by the projection range 105 and the imaging range 106. In the present embodiment, the measurement reference plane 209 is included in the measurement space and is arranged so as to bisect the depth direction distance of the measurement space 210 when observed from the imaging unit 202. The measurement surface 216 is the measurement surface closest to the projection unit 201 and the imaging unit 202 in the measurement space 210. The measurement surface 217 is the measurement surface farthest from the projection unit 201 and the imaging unit 202 in the measurement space 210. In the present embodiment, the measurement reference plane 209 is set inside the measurement space 210, but is not necessarily limited to the inside and may be outside.

  Similar to the first embodiment, the three-dimensional shape measurement apparatus according to the present embodiment performs shape measurement by the spatial encoding method, and uses the negative / positive intersection detection method as the edge position detection method.

  Also in this embodiment, the focus position of the projection unit 201 is adjusted to the measurement reference plane 209, and the focus position of the imaging unit 202 is adjusted to the back side of the measurement reference plane 209.

  FIG. 8 shows the focus position of the projection unit 201. The lens 212 schematically represents the projection optical system of the projection unit 201 as one lens, and the display element 213 displays a light / dark pattern. As shown in FIG. 8, the focus position of the projection unit 201 is aligned with the measurement reference plane 209.

  On the other hand, FIG. 9 shows a state of the focus position of the photographing unit 202. The lens 214 schematically represents the photographing optical system of the photographing unit 202 as one lens, and the photographing element 215 converts light that has entered from the lens 214 into an electrical signal. As shown in FIG. 9, the focus position of the photographing unit 202 is set to the back side with respect to the measurement reference plane 209.

  With the configuration shown in FIGS. 8 and 9, the contrast reduction due to the defocusing of the imaging unit 202 on the measurement surface 216 is larger than the contrast reduction on the measurement surface 217. Therefore, the measurement accuracy of the measurement surface 216 and the measurement accuracy of the measurement surface 217 are comparable when combined with the change in brightness of the captured image due to the distance from the imaging unit 202. In addition, since the focus position of the photographing unit 202 is behind the measurement reference plane 209, the contrast reduction on the measurement plane 217 is small as compared with the case where the focus position is on the measurement reference plane 209. Therefore, the measurement accuracy on the measurement surface 217 is improved as compared with the case where the focus position is on the measurement reference surface 209. That is, the measurement error is within a certain range over the entire photographing distance, and the accuracy is not drastically reduced, and a certain measurement accuracy can be obtained as a whole.

  As described above, by setting the focus position of the imaging unit 202 behind the measurement reference plane 209, it is possible to obtain a certain measurement accuracy in the entire measurement space 210. When the focus position of the imaging unit 202 is adjusted to the measurement reference plane 209, in order to obtain the same measurement accuracy as the present embodiment in the entire measurement space 210, the imaging performance of the imaging unit 202 is increased and the contrast of the captured image is increased. Or the amount of light projected from the projection unit 101 needs to be increased. However, since this is not necessary in the present embodiment, it is not necessary to increase the imaging performance of the photographing unit 202 more than necessary, and the number of lenses constituting the photographing unit 202 can be reduced, leading to cost reduction as a whole. Further, by reducing the output of the light source of the projection unit 201, the power consumption is reduced, and the heat generated from the light source is reduced, so that the cooling system can be made smaller, leading to miniaturization.

(Third embodiment)
With reference to FIG. 6, the structure of the three-dimensional shape measuring apparatus which concerns on 3rd Embodiment is demonstrated. The three-dimensional shape measurement apparatus includes a projection unit 301, an imaging unit 302, an imaging unit 303 (second imaging unit), and a control unit 304.

  Since the projection unit 301 uses the active stereo method in this embodiment, the projection unit 301 projects a solid image on the object 305 or performs a projection operation of irradiating a light source. The projection unit 301 can project into the space indicated by the projection range 306.

  The photographing unit 302 and the photographing unit 303 are cameras that photograph the object 305 projected by the projection unit 301. The photographing unit 302 can photograph the space indicated by the photographing range 307. The photographing unit 303 can photograph the space indicated by the photographing range 308. That is, the shooting unit 302 and the shooting unit 303 have different shooting directions. The control unit 304 is a personal computer, for example, and controls each operation of the projection unit 301, the imaging unit 302, and the imaging unit 303. The control unit 304 also executes processing for measuring the three-dimensional shape of the object 305.

  Next, a measurement reference plane and a measurement space according to the third embodiment will be described with reference to FIG. An optical axis 309 is an optical axis of the imaging unit 302 (imaging axis toward the imaging center). An optical axis 310 is an optical axis of the imaging unit 303 (imaging axis toward the imaging center). The measurement reference plane 311 is a plane including a point where the projection axis of the projection unit 301 intersects with the optical axis 309 and the optical axis 310. The measurement space 312 is a space that is included in the projection range 306, the shooting range 307, and the shooting range 308 and is defined by the projection range, the shooting range 307, and the shooting range 308. In the present embodiment, the measurement reference plane 311 is included in the measurement space, and is arranged so as to bisect the depth direction distance of the measurement space 312 when observed from the imaging unit 302. The measurement surface 313 is the measurement surface closest to the projection unit 301, the imaging unit 302, and the imaging unit 303 in the measurement space 312. The measurement surface 314 is the measurement surface farthest from the projection unit 301, the imaging unit 302, and the imaging unit 303 in the measurement space 312. In the present embodiment, the measurement reference plane 311 is set inside the measurement space 312, but is not necessarily limited to the inside and may be outside.

  In the three-dimensional shape measurement apparatus according to this embodiment, unlike the first and second embodiments, the object 305 projected by the projection unit 301 is obtained from each image photographed by the photographing unit 302 and the photographing unit 303. An active stereo method (stereo method) that calculates the distance to the object 305 using the principle of triangulation is adopted. Therefore, unlike the first and second embodiments, there is no need to project a pattern from the projection unit 301, so a solid image may be projected from the projection unit 301. Furthermore, the projection unit 301 may be an illumination unit such as a light bulb.

  In the active stereo method, a feature amount such as an edge of the object 305 is detected from a photographed image, and triangulation is performed by associating the images photographed by the photographing unit 302 and the photographing unit 303 with each other. Therefore, the higher the contrast of the edge of the object 305 photographed by the photographing unit 302 and the photographing unit 303, the higher the edge position detection accuracy. Further, the SN of the photographing unit 302 and the photographing unit 303 is improved when the brightness of the images photographed by the photographing unit 302 and the photographing unit 303 is high. Therefore, the projection from the projection unit 301 has higher edge position detection accuracy when the brightness is higher.

  Therefore, in the present embodiment as well, as in the first and second embodiments, the focus positions of the photographing unit 302 and the photographing unit 303 are set to the back side with respect to the measurement reference plane 311.

  FIG. 12 shows the focus positions of the photographing unit 302 and the photographing unit 303. The lens 315 schematically represents the photographing optical system of the photographing unit 302 with one lens. The lens 317 schematically represents the photographing optical system of the photographing unit 303 with a single lens. The imaging element 316 and the imaging element 318 convert light entering from the lens 315 and the lens 317, respectively, into an electrical signal.

  With the configuration shown in FIG. 12, the contrast reduction due to defocusing of the imaging unit 302 and the imaging unit 303 on the measurement surface 313 is larger than the contrast reduction on the measurement surface 314. Therefore, the measurement accuracy of the measurement surface 313 and the measurement accuracy of the measurement surface 314 are comparable when combined with the change in brightness of the captured image depending on the distance from the imaging unit 302 and the imaging unit 303. In addition, since the focus positions of the imaging unit 302 and the imaging unit 303 are behind the measurement reference plane 311, the contrast reduction on the measurement plane 314 is smaller than when the focus position is on the measurement reference plane 311. Therefore, the measurement accuracy on the measurement surface 314 is improved as compared with the case where the focus position is on the measurement reference surface 311. That is, the measurement error is within a certain range over the entire photographing distance, and the accuracy is not drastically reduced, and a certain measurement accuracy can be obtained as a whole.

  As described above, by setting the focus positions of the imaging unit 302 and the imaging unit 303 behind the measurement reference plane 311, it is possible to obtain a certain measurement accuracy in the entire measurement space 312. When the focus positions of the imaging unit 302 and the imaging unit 303 are aligned with the measurement reference plane 311, the imaging of the imaging unit 302 and the imaging unit 303 is obtained in order to obtain the same measurement accuracy as the present embodiment over the entire measurement space 312. It is necessary to improve the contrast of the captured image by improving the performance or to increase the amount of light projected from the projection unit 301. However, since this is not necessary in the present embodiment, it is not necessary to increase the imaging performance of the photographing unit 302 and the photographing unit 303 more than necessary, and the number of lenses constituting the photographing unit 302 and the photographing unit 303 can be reduced. As a whole, it leads to cost reduction. Further, by reducing the output of the light source of the projection unit 301, the power consumption can be reduced, and the heat generated from the light source can be reduced, so that the cooling system can be reduced, leading to miniaturization.

(Other embodiments)
The present invention can also be realized by executing the following processing. That is, software (program) that realizes the functions of the above-described embodiments is supplied to a system or apparatus via a network or various storage media, and a computer (or CPU, MPU, or the like) of the system or apparatus reads the program. It is a process to be executed.

  101: Projection unit, 102: Imaging unit, 103: Control unit, 104: Object, 105: Projection range, 106: Imaging range, 107, 108: Optical axis, 109: Measurement reference plane, 110: Measurement space, 111: Light / dark pattern, 112, 114: lens, 113: display element, 115: imaging element, 116, 117: measurement surface

Claims (7)

Projection means for projecting a pattern including a bright part and a dark part onto an object;
Imaging means for imaging the object while a pattern is projected by the projection means;
Detecting means for detecting an edge position indicating a boundary between a bright part and a dark part of the pattern from an image picked up by the image pickup means;
Measuring means for measuring the three-dimensional shape of the object based on the detected edge position;
The focal position of the imaging means is a measurement including a position determined based on an axis passing through the center position of the projection range of the projection means and an axis passing through the center position of the imaging range of the imaging means when viewed from the imaging means. It is set behind the reference plane,
The focal position of the projection means is set on the measurement reference plane ,
The contrast device between the bright part and the dark part in the image has a maximum value in a region deeper than the measurement reference plane . The position determined based on the axis passing through the center position of the projection range of the projection means and the axis passing through the center position of the imaging range of the imaging means as viewed from the projection means is the center position of the projection range of the projection means The measuring apparatus according to claim 1, wherein the measuring device is an intersection position between an axis passing through and an axis passing through a center position of an imaging range of the imaging means. It said measuring means, measuring device according to claim 1 or 2, characterized in that to measure the three-dimensional shape of the object by a spatial encoding method. It said measuring means, measuring device according to claim 1 or 2, characterized in that to measure the three-dimensional shape of the object by the phase shift method. Focus position of the projection means, measuring device according to any one of claims 1 to 4, characterized in that it is fixed. Measurement apparatus according to any one of claims 1 to 5, wherein the imaging element of the imaging means is one. Projection means for projecting a pattern including a bright part and a dark part onto an object;
Imaging means for imaging the object while a pattern is projected by the projection means;
Detecting means for detecting an edge position indicating a boundary between a bright part and a dark part of the pattern from an image picked up by the image pickup means;
Measuring means for measuring the three-dimensional shape of the object based on the detected edge position;
The focal position of the imaging means is a measurement including a position determined based on an axis passing through the center position of the projection range of the projection means and an axis passing through the center position of the imaging range of the imaging means when viewed from the imaging means. It is set behind the reference plane,
The focal position of the projection means is set on the measurement reference plane,
The position determined based on the axis passing through the center position of the projection range of the projection means and the axis passing through the center position of the imaging range of the imaging means as viewed from the projection means is the center position of the projection range of the projection means A measuring device characterized by being an intersection position of an axis passing through and an axis passing through the center position of the imaging range of the imaging means.

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