JP2010181325A - Three-dimensional coordinate measuring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a means for removing an influence of background light, mercury lamp light, or strobe light reflected by a measuring object, in a three-dimensional coordinate measuring device for measuring a three-dimensional coordinate of the measuring object from a plurality of images obtained by photographing the measuring object from different angles. <P>SOLUTION: The three-dimensional coordinate measuring device 1 includes: a target plate 2 provided with reflecting materials 14, 15 for reflecting light, and mounted on a vehicle S; a plurality of imaging devices 3 for photographing an image of the vehicle S; a stroboscopic device 4 for irradiating light to the vehicle S; and an image processing device 5 for calculating a three-dimensional coordinate of the vehicle S based on a plurality of images obtained by photographing the same target plate 2 from different angles. Color filters 16, 17 for transmitting only light having a specific color in light emitted from the stroboscopic device 4 are provided at least on the surface of the reflecting materials 14, 15 on the target plate 2. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a three-dimensional coordinate measuring apparatus that takes an image of an object to be measured and measures its three-dimensional coordinates. In particular, the influence of background light, light from a mercury lamp, or strobe light that irradiates the object to be measured at the time of photographing. The present invention relates to a three-dimensional coordinate measuring apparatus that can be eliminated.

  In an automobile inspection called a so-called vehicle inspection, each part of the vehicle is measured in order to inspect whether a vehicle to be inspected (hereinafter simply referred to as “vehicle”) satisfies a statutory standard. And as this measuring means, the three-dimensional coordinate measuring apparatus which measures the three-dimensional coordinate of a vehicle based on the several image which image | photographed the vehicle from a different angle is used. In this three-dimensional coordinate measuring apparatus, a plurality of image pickup devices are installed around the vehicle, and each image pickup device takes an image of the vehicle while firing a strobe. At this time, a member called a target plate is attached to each measurement point of the vehicle, and a retroreflecting material is provided on the surface of each target plate. As a result, strobe light reflected by the retroreflecting material appears whitish in each photographed image. Then, for each image, an area in which strobe light is projected whitish is extracted as a feature point of the image, and feature points are associated with each other for a plurality of images obtained by photographing the same target plate from different angles. Thereby, the three-dimensional coordinates of the retroreflecting material can be specified for each target plate, and the three-dimensional coordinates of the vehicle can be calculated based on the three-dimensional coordinates (see Patent Document 1).

Japanese Patent No. 3637416

  However, in the conventional three-dimensional coordinate measuring apparatus, the three-dimensional coordinates of the retroreflecting material are erroneously specified, and the three-dimensional coordinates of the vehicle may not be calculated correctly. In other words, for each photographed image, an area where the strobe light reflected by the retroreflecting material is projected as whitish should be extracted as a feature point, but another whitish area existing on the image is erroneously extracted as a feature point. There is a case. In this case, when the feature points are associated with each other for a plurality of images, a point called a ghost is generated by specifying the three-dimensional coordinates of the retroreflecting material at a position different from the actual position.

  Here, as a whitish area that is erroneously extracted as a feature point in each image, an area in which background light such as sunlight is projected, an area in which light from a mercury lamp is reflected on a vehicle body or a glass surface, or an image For example, an area where the light of a strobe flashed at the time of shooting is reflected on the vehicle body or glass surface.

  The present invention has been made in view of such problems, and in a three-dimensional coordinate measuring apparatus for measuring three-dimensional coordinates of a vehicle from a plurality of images obtained by photographing the vehicle from different angles during vehicle inspection, a background light, a mercury lamp It is possible to provide a means for eliminating the influence of the light of the stroboscope light or the strobe light reflected from the vehicle body or the glass surface.

  In order to achieve the above object, a three-dimensional coordinate measuring apparatus according to the present invention includes a target plate provided with a reflecting material that reflects light, and a plurality of images of the object to be measured from different angles. A plurality of images taken by the imaging device from different angles of the same target plate and a strobe device that irradiates light to the object to be measured; An image processing device that extracts regions where light reflected by the reflecting material is projected as feature points of the respective images, and associates the feature points of the respective images with each other to measure the three-dimensional coordinates of the object to be measured; , And transmits only light of a specific color out of the light emitted from the strobe device to at least the surface of the reflecting material of the target plate. One in which color filter is provided.

  In the three-dimensional coordinate measuring apparatus according to the present invention, each imaging device captures an image of the object to be measured in both a state where light is emitted from the strobe device and a state where light is not emitted. The image processing device creates a difference image from an image shot in a state where light is irradiated to the object to be measured and an image shot in a state where light is not irradiated, and the measured object is based on the difference image It measures the three-dimensional coordinates of an object.

  In the three-dimensional coordinate measuring apparatus according to the present invention, each of the imaging devices is in a state in which the target plate is attached to the object to be measured and a state in which the target plate is not attached. Each of the images is taken, and the image processing device creates a difference image from an image taken with the target plate attached to the object to be measured and an image taken with the target plate not attached. The three-dimensional coordinates of the object to be measured are measured based on the image.

  In the three-dimensional coordinate measuring apparatus according to the present invention, the reflector is provided on both the front and back surfaces of the target plate so that the center positions thereof coincide with each other in plan view.

  According to the three-dimensional coordinate measuring apparatus according to the present invention, since the color filter that transmits only the light of a specific color is provided on the surface of the reflecting material, the light of the strobe device reflected by the reflecting material is the difference image. It appears as a red area. On the other hand, the light of the strobe device reflected by the vehicle body or the glass surface is projected as a whitish area in the difference image. Therefore, the region where the light of the strobe device reflected by the vehicle body or the glass surface is projected is not erroneously extracted as a feature point, and the three-dimensional coordinates of the object to be measured can be calculated more accurately.

  Further, according to the three-dimensional coordinate measuring apparatus according to the present invention, a difference image is created from an image photographed in a state in which light is irradiated on the object to be measured and an image photographed in a state in which light is not irradiated. Based on the image, three-dimensional coordinates of the object to be measured are calculated. Here, the light constantly irradiating the object to be measured, such as background light or light from a mercury lamp, is displayed in an image captured in any state, and thus is not displayed in a difference image created from both images. Therefore, the region where the background light or the light from the mercury lamp is projected is not erroneously extracted as a feature point, and the three-dimensional coordinates of the object to be measured can be calculated more accurately.

  Further, according to the three-dimensional coordinate measuring apparatus according to the present invention, a difference image is created from an image photographed with the target plate attached to the object to be measured and an image photographed without the target plate attached. Based on the image, three-dimensional coordinates of the object to be measured are calculated. Here, since the light other than the strobe light reflected by the reflecting material of the target plate is displayed in the image captured in any state, it is not displayed in the difference image created from both images. Therefore, a region where light other than the strobe light reflected by the reflecting material is projected is not erroneously extracted as a feature point, and the three-dimensional coordinates of the object to be measured can be calculated more accurately.

  Further, according to the three-dimensional coordinate measuring apparatus according to the present invention, the reflecting material is provided on both the front and back surfaces of the target plate so that the center positions thereof coincide with each other in plan view. Whichever side of the image is taken by the imaging device, the light of the strobe device reflected by the reflecting material is projected in the image, and the three-dimensional coordinates of the reflecting material can be specified. Thereby, an imaging device can be installed in a wider range.

The schematic diagram which showed the whole structure of the three-dimensional coordinate measuring apparatus which concerns on the Example of this invention in bird's-eye view. The schematic perspective view which looked at the target board from the surface side. The schematic perspective view which looked at the target board from the back side. The schematic longitudinal cross-sectional view which shows the AA cross section in FIG. The schematic perspective view which shows an example of the attachment state to the vehicle of a target board. FIG. 2 is a schematic perspective view illustrating configurations of an imaging device and a strobe device.

  First, the configuration of a three-dimensional coordinate measuring apparatus according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram showing an overview of the overall configuration of the three-dimensional coordinate measuring apparatus 1 according to the present embodiment. The three-dimensional coordinate measuring apparatus 1 includes a plurality of target plates 2 attached to predetermined locations of a vehicle S to be subjected to automobile inspection, four imaging devices 3 installed around the vehicle S, and each imaging device 3. And four strobe devices 4 installed at positions close to each other, and an image processing device 5 connected to each imaging device 3. In FIG. 1, the measurement space K is indicated by a one-dot chain line.

  The target plate 2 serves as a mark indicating a measurement point when measuring the three-dimensional coordinates of the vehicle S. 2 to 4 are diagrams showing the configuration of the target plate 2. FIG. 2 is a schematic perspective view seen from the front surface side, FIG. 3 is a schematic perspective view seen from the back surface side, and FIG. It is a schematic longitudinal cross-sectional view which shows an AA cross section. The target plate 2 includes a main body portion 6 having a substantially arc shape in plan view, reflecting portions 7 and 8 provided at a substantially central position of the main body portion 6, and a vehicle attachment portion 9 provided at a side end of the main body portion 6. have.

  As shown in FIGS. 2 to 4, the main body 6 is formed by bonding a front plate 10 and a back plate 11 having the same shape in a plan view, and a substantially central position between the front plate 10 and the back plate 11. Are formed with concave grooves 12 and 13 each having a substantially circular shape in plan view. The reflecting portions 7 and 8 are provided inside the concave grooves 12 and 13, respectively. Note that the shape of the main body 6 in plan view is not limited to the present embodiment, and the design can be changed as appropriate. Further, in the present embodiment, the main body portion 6 is configured by bonding the front side plate 10 and the back side plate 11, but the main body portion 6 can also be configured by a single thick plate. Furthermore, the shape of the concave grooves 12 and 13 in a plan view and the positions where they are formed are not limited to the present embodiment, and can be appropriately changed in design. Further, the reflecting portions 7 and 8 may be provided on the flat surfaces of the front side plate 10 and the back side plate 11 without forming the concave grooves 12 and 13.

  The reflectors 7 and 8 are for reflecting the strobe light emitted from the strobe device 4 toward the image pickup device 3. As shown in FIG. 4, the reflecting portions 7 and 8 are provided on both the front and back surfaces of the target plate 2 by being provided inside the groove 12 of the front plate 10 and the groove 13 of the back plate 11, respectively. . Each of the reflecting portions 7 and 8 is composed of reflecting materials 14 and 15 provided at the bottom of the concave grooves 12 and 13 and color filters 16 and 17 provided so as to cover the surfaces of the reflecting materials 14 and 15. Has been.

  The reflectors 14 and 15 are retroreflectors that always reflect the light incident from any direction in the incident direction, and are formed in a circular shape having substantially the same diameter as the concave grooves 12 and 13 in plan view. As shown in FIG. 4, the reflecting material 14 provided on the surface of the target plate 2 and the reflecting material 15 provided on the back surface are provided so as to be substantially concentric in a plan view. Thereby, even if the imaging device 3 takes an image from either the front surface side or the back surface side of one target plate 2, strobe light reflected by the reflectors 14 and 15 of the target plate 2 in each captured image. Since these are projected and they can be regarded as light reflected by the same reflector, the three-dimensional coordinates of the reflectors 14 and 15 can be specified by performing image processing on these captured images. In this embodiment, as the retroreflective material, a so-called exposure lens type, which has a high reflection efficiency, is used. Instead, an encapsulated lens type, a capsule lens type, a filter pasting type, and a microprism type are used. It is also possible to use a retroreflecting material such as. Moreover, the material of the reflectors 14 and 15 is sufficient as long as it can reflect the light emitted from the strobe light toward the imaging device 3, and is not limited to the retroreflector. In addition, the shape of the reflectors 14 and 15 can be changed as appropriate according to the shape of the concave grooves 12 and 13.

  On the other hand, the color filters 16 and 17 are for extracting only light of a specific color from the strobe light. The color filters 16 and 17 are sheet-like members formed in a circular shape having substantially the same diameter as the concave grooves 12 and 13 in plan view, and have a characteristic of transmitting only red light. Note that the color of light transmitted through the color filters 16 and 17 is not limited to red, and may be, for example, blue, green, yellow, or gray. However, as will be described later, the light emitted from the strobe device 4 and reflected by the reflecting portions 7 and 8 of the target plate 2 in the image photographed by the image pickup device 3 is also emitted from the strobe device 4 and the vehicle body. And the color filters 16 and 17 that transmit only red light, or the color filters 16 and 17 that transmit only blue light, as in this embodiment, are the most suitable for distinguishing from the light reflected from the glass surface. It is. This is because the light reflected by the vehicle body or the glass surface appears whitish in the photographed image, so that the light reflected by the reflecting portions 7 and 8 of the target plate 2 is taken into consideration when it is easy to distinguish it from the photographed image. The color when projected inside is preferably a color in which the luminance ratio between the highest luminance and the lowest luminance among the three primary colors of light is large and the maximum luminance of the three primary colors is as large as possible. The two conditions are satisfied because the color filters 16 and 17 transmit only red light or only blue light. The color filters 16 and 17 that transmit only green light have a characteristic that the maximum luminance is lower than that of red or blue, although the condition of the luminance ratio is satisfied.

  The color filters 16 and 17 may be provided so as to cover at least the surfaces of the reflectors 14 and 15. For example, the color filters 16 and 17 may be provided so as to cover the entire surface of the main body 6. Further, the color filters 16 and 17 are not necessarily provided in close contact with the reflecting materials 14 and 15, and may be provided at positions separated from the reflecting materials 14 and 15 by a predetermined distance.

  The vehicle attachment portion 9 is for attaching the target plate 2 to the vehicle S. As shown in FIGS. 2 and 3, the vehicle attachment portion 9 is a longitudinal member having a rectangular longitudinal section made of a permanent magnet, and one side surface thereof is fixed to the main body portion 6. In addition, the shape of the vehicle mounting portion 9, the position of fixing to the main body portion 6, the number, and the like are not limited to the present embodiment and can be appropriately changed in design. The means for attaching the target plate 2 to the vehicle S is not limited to the magnetizing force of the permanent magnet. For example, the vehicle attachment portion 9 is made of an adhesive sheet, and the vehicle attachment portion 9 is affixed to the vehicle body or the glass surface. 2 may be attached to the vehicle S.

  The target plate 2 configured as described above is attached to a predetermined measurement point in the vehicle S according to the item to be measured. FIG. 5 is a schematic perspective view showing an example of a state in which the target plate 2 is attached to the vehicle S. In this embodiment, the target plate 2 for measuring the vehicle width is attached to the left and right side surfaces Sa of the vehicle S, and the target plate 2 for measuring the vehicle height is attached to the roof surface Sb and the bonnet upper surface Sc. . Of course, the attachment position of the target plate 2 to the vehicle S can be changed to an arbitrary position corresponding to the measurement item within the range that can be imaged by the imaging device 3.

  The imaging device 3 is for acquiring an image of the vehicle S, and for example, a digital camera, a silver salt camera, a video camera, or the like can be used. Here, FIG. 6 is a schematic perspective view showing configurations of the imaging device 3 and the strobe device 4. The imaging device 3 includes a camera body 18, a support arm 19 that supports the camera body 18, and a base plate 20 that is fixed to the base end of the support arm 19. The base plate 20 is slidable in the vertical direction along the two guide rails 21 laid on the wall surface, and the position of the camera body 18 can be adjusted in the vertical direction. Further, the support arm 19 supports the camera body 18 so as to be rotatable, and the tilt angle of the camera body 18 can be adjusted. Note that the number of installed image pickup apparatuses 3 is not limited to four in the present embodiment, and may be any number. Further, the imaging device 3 may be used by being held by the user in addition to being fixed to the wall surface as in the present embodiment.

  The strobe device 4 is for irradiating light toward the target plate 2 during photographing by the imaging device 3. As shown in FIG. 6, the strobe device 4 includes a strobe body 22, a support arm 23 that supports the strobe body 22, and a base plate 24 that is fixed to the base end of the support arm 23. . The base plate 24 of the strobe device 4 is slidable in the vertical direction along the two guide rails 21 at a position above the base plate 20 of the image pickup device 3. Can be adjusted vertically. Further, the support arm 23 of the strobe device 4 also supports the strobe body 22 so as to be rotatable, and the inclination angle of the strobe body 22 can be adjusted.

  The image processing device 5 calculates the three-dimensional coordinates of the vehicle S based on a plurality of images taken by the imaging device 3. More specifically, when a plurality of pieces of image data obtained by photographing the same target plate 2 from different angles are input from the imaging device 3, the image processing device 5 reflects on the reflecting materials 14 and 15 of the target plate 2. The position where the strobe light is projected in each image is extracted as a feature point of each image. Thereafter, the image processing device 5 identifies the three-dimensional coordinates of the reflectors 14 and 15 by associating the feature points of each image. Here, the association between feature points is based on the conventionally known triangulation principle, and a straight line is drawn from the focus of each imaging device 3 to the feature point of each image, and the same target plate 2 is photographed. It means that the intersection where the straight lines drawn in each image intersect is set as the position where the reflectors 14 and 15 exist. Then, the image processing device 5 calculates the three-dimensional coordinates of the vehicle S based on the three-dimensional coordinates specified for the reflectors 14 and 15 of each target plate 2. In this embodiment, as shown in FIG. 1, the image processing device 5 is connected to the imaging device 3 and image data is directly input from the imaging device 3 to the image processing device 5. When 3 is a silver salt camera, the captured image may be converted into digital data using a scanner (not shown) or the like, and then image data may be input to the image processing apparatus 5 from the scanner.

  Next, the three-dimensional coordinate measuring procedure of the vehicle S by the three-dimensional coordinate measuring apparatus 1 and the operation and effect thereof will be described. First, the imaging device 3 and the strobe device 4 are positioned. Specifically, although not shown in detail in the figure, a plurality of target plates 2 are arranged at predetermined intervals on the floor surface where the vehicle S is not yet arranged. Then, each target plate 2 is photographed from different angles using the imaging device 3, and the image data is input to the image processing device 5 to calculate the interval between the target plates 2. Then, by comparing the calculation result with the actual distance between the target plates 2, the vertical position and the tilt angle of the camera body 18 constituting the imaging device 3 are appropriately adjusted. Also, with respect to the strobe device 4, the vertical position and inclination angle of the strobe body 22 constituting the strobe device 4 are appropriately adjusted so that the strobe light reflected by the target plate 2 is projected with a sufficiently high brightness in the captured image. .

  Next, vehicle photographing by the imaging device 3 is performed. At this time, each imaging device 3 first photographs the vehicle S by operating the strobe device 4 and irradiating light in a state where the target plate 2 is not attached to the vehicle S. Next, in a state in which the target plate 2 is attached to the vehicle S, each imaging device 3 operates the strobe device 4 to irradiate light and photograph the vehicle S. Finally, each imaging device 3 photographs the vehicle S without operating the strobe device 4 and irradiating light with the target plate 2 attached to the vehicle S. Each imaging device 3 inputs image data captured in each state to the image processing device 5.

  Next, the three-dimensional coordinates of the vehicle S are calculated by the image processing device 5. More specifically, the image processing device 5 first calculates a difference based on both image data of an image photographed with light from the strobe device 4 and an image photographed without light from the strobe device 4. Create an image. Here, the background light such as sunlight and the light from the mercury lamp are always radiated to the vehicle S, so that they are always projected in the photographed image regardless of whether the stroboscopic device 4 irradiates light. Therefore, the background light and the light from the mercury lamp are not projected on the difference image.

  Then, the image processing device 5 extracts feature points for each created difference image. That is, as described above, the position where the strobe light reflected by the reflectors 14 and 15 of the target plate 2 is projected in the difference image is extracted as the feature point of the difference image. At this time, since the background light and the light from the mercury lamp are not projected in the difference image, the image processing apparatus 5 does not erroneously extract these lights as feature points. Further, as described above, since the surfaces of the reflectors 14 and 15 are covered with the color filters 16 and 17 that transmit only red light, the strobe light reflected by the reflectors 14 and 15 is red in the difference image. It is projected as the area. On the other hand, the strobe light reflected from the vehicle body or the glass surface is projected as a whitish region in the difference image. Therefore, the image processing apparatus 5 does not mistake the strobe light reflected by the vehicle body or the glass surface as the strobe light reflected by the reflectors 14 and 15 and extract it as a feature point. In this way, when extracting feature points for each difference image, accurate extraction is possible by eliminating the influence of background light, mercury lamp light, and strobe light reflected from the vehicle body or glass surface.

  Thereafter, as described above, the image processing device 5 identifies the three-dimensional coordinates of the reflecting materials 14 and 15 by associating the feature points of each difference image, and identifies the reflecting materials 14 and 15 of each target plate 2. Based on the three-dimensional coordinates, the three-dimensional coordinates of the vehicle S are calculated.

  Further, the image processing device 5 creates a difference image based on both image data of an image taken with the target plate 2 attached to the vehicle S and an image taken without the target plate 2 attached. Here, light other than the strobe light reflected by the reflectors 14 and 15 of the target plate 2 is displayed in the image captured in any state, and thus is not displayed in the difference image created from both images. And the image processing apparatus 5 extracts the feature point about each produced difference image similarly to the above-mentioned. At this time, since the light other than the strobe light reflected by the reflectors 14 and 15 is not projected in the difference image, the image processing apparatus 5 does not erroneously extract these lights as feature points. Can be extracted accurately. Thereafter, as described above, the image processing apparatus 5 specifies the three-dimensional coordinates of the reflecting materials 14 and 15 by associating the feature points of each difference image, and specifies the reflecting materials 14 and 15 of each target plate 2. Based on the three-dimensional coordinates, the three-dimensional coordinates of the vehicle S are calculated.

  The three-dimensional coordinate measuring apparatus according to the present invention can be used not only for continuous inspection called so-called vehicle inspection, but also for structural inspection and street inspection. In the present embodiment, the vehicle inspection has been described as an example of the vehicle inspection. However, the vehicle inspection can also be used for inspection of a motorcycle, a motorbike and the like.

DESCRIPTION OF SYMBOLS 1 3D coordinate measuring device 2 Target board 3 Imaging device 4 Strobe device 5 Image processing device 14, 15 Reflective material 16, 17 Color filter S Vehicle (measurement object)

Claims (7)

A target plate that is provided with a reflective material that reflects light and is attached to an object to be measured;
A plurality of imaging devices for capturing images of the object to be measured from different angles;
A strobe device that emits light to the object to be measured;
With respect to a plurality of images taken by the imaging device from the same target plate from different angles, regions where light emitted from the strobe device and reflected by the reflecting material is projected are used as feature points of the images, respectively. An image processing apparatus that extracts and measures the three-dimensional coordinates of the object to be measured by associating the feature points of each image
A three-dimensional coordinate measuring apparatus comprising:
3. A three-dimensional coordinate measuring apparatus, wherein a color filter that transmits only light of a specific color out of light emitted from the strobe device is provided on at least a surface of a reflective material of the target plate. Each of the imaging devices takes an image of the object to be measured in both a state where light is emitted from the strobe device and a state where light is not emitted,
The image processing apparatus creates a difference image from an image shot in a state where light is irradiated on the object to be measured and an image shot in a state where light is not irradiated, and the object to be measured is based on the difference image The three-dimensional coordinate measuring apparatus according to claim 1, wherein the three-dimensional coordinate is measured. Each of the imaging devices takes an image of the object to be measured in both the state in which the target plate is attached to the object to be measured and the state in which the target plate is not attached,
The image processing device creates a difference image from an image taken with the target plate attached to the object to be measured and an image taken without the target plate attached, and based on the difference image, the object to be measured The three-dimensional coordinate measuring apparatus according to claim 1, wherein the three-dimensional coordinate of the measurement object is measured. A target plate that is provided with a reflective material that reflects light and is attached to an object to be measured;
A plurality of imaging devices for capturing images of the object to be measured from different angles;
A strobe device that emits light to the object to be measured;
With respect to a plurality of images taken by the imaging device from the same target plate from different angles, areas where light emitted from the strobe device and reflected by the reflecting material are projected are used as feature points of the images, respectively. An image processing apparatus that extracts and measures the three-dimensional coordinates of the object to be measured by associating the feature points of each image
A three-dimensional coordinate measuring apparatus comprising:
Each of the imaging devices takes an image of the object to be measured in both a state where light is emitted from the strobe device and a state where light is not emitted,
The image processing device creates a difference image from an image shot in a state of irradiating light on the object to be measured and an image shot in a state of not irradiating light, and the object to be measured is based on the difference image A three-dimensional coordinate measuring apparatus characterized by measuring the three-dimensional coordinates. Each of the imaging devices takes an image of the object to be measured in both the state in which the target plate is attached to the object to be measured and the state in which the target plate is not attached,
The image processing apparatus creates a difference image from an image taken with the target plate attached to the object to be measured and an image taken without the target plate attached, and based on the difference image, The three-dimensional coordinate measuring apparatus according to claim 4, wherein the three-dimensional coordinate of the measurement object is measured. A target plate that is provided with a reflective material that reflects light and is attached to an object to be measured;
A plurality of imaging devices for capturing images of the object to be measured from different angles;
A strobe device that emits light to the object to be measured;
With respect to a plurality of images taken by the imaging device from the same target plate from different angles, regions where light emitted from the strobe device and reflected by the reflecting material is projected are used as feature points of the images, respectively. An image processing device that extracts and measures the three-dimensional coordinates of the object to be measured by associating the feature points of each image;
A three-dimensional coordinate measuring apparatus comprising:
Each of the imaging devices takes an image of the object to be measured in both the state in which the target plate is attached to the object to be measured and the state in which the target plate is not attached,
The image processing device creates a difference image from an image taken with the target plate attached to the object to be measured and an image taken without the target plate attached, and based on the difference image, the object to be measured A three-dimensional coordinate measuring apparatus for measuring a three-dimensional coordinate of a measurement object.   The three-dimensional coordinate measuring apparatus according to any one of claims 1 to 6, wherein the reflecting material is provided on both the front and back surfaces of the target plate so that the center positions thereof coincide with each other in a plan view.

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