JP6131001B2 - 3D pattern for camera calibration - Google Patents

Description

  The present invention relates to a three-dimensional pattern for camera calibration used for camera calibration required for three-dimensional image measurement using a camera.

以上により、透視投影行列あるいは画像の歪みパラメータを含めた１２個のパラメータを求めることができれば、画像中の画像座標から対象物体の３次元的な情報を得ることができる。
この透視投影行列あるいは１２個のパラメータを得る作業がカメラキャリブレーションと呼ばれている。 In general, image measurement for recognizing the shape of a target object in a three-dimensional space is performed using a camera. In this type of image measurement, the three-dimensional coordinates of the target object are measured using the image coordinates in the captured image.
The relationship between the three-dimensional coordinates and the image coordinates obtained from the captured image is as follows.

As described above, if 12 parameters including the perspective projection matrix or the distortion parameter of the image can be obtained, the three-dimensional information of the target object can be obtained from the image coordinates in the image.
The operation of obtaining this perspective projection matrix or 12 parameters is called camera calibration.

  As described above, in image measurement, it is indispensable to obtain an external parameter that represents the relationship between the camera coordinate system and the world coordinate system and an internal parameter that represents the relationship between the camera coordinate system and the image coordinate system. These external parameters and internal parameters can be obtained by measuring the position and orientation of the camera or actually measuring the focal length of the lens based on information on the camera dimensions and installation position. Since accurate measurement is difficult and requires a lot of time, in actual operation, a calibration board with a calibration pattern such as a checkerboard pattern is photographed with a camera, and the lattice points are feature points. The three-dimensional coordinates and the coordinates of the points obtained by projecting the points onto the two-dimensional image are obtained and calculated using such feature points.

  Various types of camera calibration using such a calibration pattern have been proposed, and a method using a three-dimensional pattern and a method using a two-dimensional pattern are well known.

The three-dimensional pattern is exemplified in Patent Document 1, for example. As shown in FIG. 17, this pattern includes an xy plane, a yz plane, and a zx plane, and each plane is marked with a known coordinate position.
For example, Non-Patent Document 1 proposes camera calibration using such a three-dimensional pattern. In the method of this document 1, a single image is photographed so that a three-dimensional pattern with known three-dimensional information is included in a part of the photographed image, and a three-dimensional coordinate based on a certain point and a two-dimensional image in the photographed image. Camera parameters are obtained by calculating a perspective projection matrix that associates coordinates. In the case of this method, the external parameters and internal parameters of the camera can be obtained by one shooting.

The two-dimensional pattern is exemplified in Patent Document 2, for example. As shown in FIG. 18, this pattern is a grid-like plane pattern that is arranged so that the colors in the grids are alternately inverted. In this case, the white and black grids are alternately grid-shaped. It is a checkered pattern.
For example, Non-Patent Document 2 proposes camera calibration using such a two-dimensional pattern. In the method of this document 2, a two-dimensional pattern is photographed from multiple directions with a camera, a calculation image is calculated from the positional relationship between the camera and the two-dimensional pattern and the information of the camera model simulated in the calculation, Compare the actual captured image with the position of the two-dimensional pattern in the calculated image, and use the displacement amount of both positions as an evaluation target so that the sum of squares of the displacement amount is minimized. Non-linear optimization is performed on the parameter to obtain an optimum value. In the case of this method, it is possible to calculate a parameter for correcting image distortion.

JP 2001-82941 A JP2012-7980 Masatomi Okutomi, “Digital Image Processing”, CG-ARTS Association, 2006 Z. Zhang, "A flexible new technique for camera calibration", IEEE Transactions on Pattern Analysis and Machine Intelligence, 22 (11): 1330-1334, 2000.

  By the way, it is known that an image taken by a digital camera using an optical lens such as a CCD camera has distortion due to distortion of the lens, and the distortion is larger toward the periphery of the image. On the other hand, the conventional method using the three-dimensional pattern cannot correct the distortion generated in the image, and as a result, there is a problem that the accuracy of image measurement may be deteriorated. Further, although the above-described conventional method using a two-dimensional pattern can correct image distortion, there is a problem in that it takes a lot of time for image acquisition processing because it is necessary to acquire a plurality of images. is there.

Therefore, the inventor of the present application pays attention to a three-dimensional pattern having an advantage that can be taken only once, and as a result of extensive research on correcting the distortion of the three-dimensional pattern and the image, a structure capable of correcting the distortion of the image is obtained. The inventors have found a three-dimensional pattern and have proposed the present invention.
According to the present invention, in this kind of three-dimensional pattern for camera calibration, it is possible to perform camera calibration easily and with high accuracy by greatly reducing the execution time, and contribute to high-accuracy image measurement. Objective.

In order to achieve the above object, the present invention provides:
A camera calibration 3D pattern for measuring camera parameters necessary for 3D image measurement using a camera,
In the same vertical plane or horizontal plane, a plane having a minimum or maximum height as a reference plane at any position including the center, radially around the reference plane from the reference plane to the periphery, and A plurality of surfaces that increase or decrease in height as they move away from the reference surface in the circumferential direction are formed, and four independent regions each including each corner of the outermost four corners away from the reference surface have heights The largest or smallest surface is formed,
Each of the plurality of surfaces including the surface having the maximum or minimum height includes feature points with known three-dimensional coordinates with respect to the arbitrary surface.
This is the gist.

Further, this three-dimensional pattern is embodied as follows.
(1) All or some of the plurality of surfaces are formed in parallel or non-parallel to the same vertical surface or horizontal surface .
(2) All or some of the plurality of surfaces are formed in a planar shape or a non-planar shape .
(3) The stepped portions of the plurality of surfaces are all or partially formed at right angles or non-right angles with respect to the same vertical surface or horizontal surface .
(4) The feature points are regularly or irregularly arranged on a plurality of surfaces .
(5) The plurality of surfaces are formed on one surface of a rectangular parallelepiped or cubic block or a rectangular board .
(6) A plurality of surfaces can be separated at a predetermined position, and a block or board can be divided into a plurality of small blocks or small boards, and the plurality of surfaces can be expanded and contracted two-dimensionally or three-dimensionally. Composed .

In the three-dimensional pattern for camera calibration of the present invention, a surface having a minimum or maximum height as a reference surface at an arbitrary position including the center in the same vertical plane or horizontal plane, and a reference around the reference plane A plurality of surfaces are formed that increase or decrease in height radially from the surface toward the periphery and away from the reference surface in the circumferential direction, and include four corners each including the four corners of the outermost periphery away from the reference surface . A surface having the maximum or minimum height is formed in an independent area, and each of a plurality of surfaces including the surface having the maximum or minimum height has a feature point whose three-dimensional coordinates are known on the basis of an arbitrary surface. Therefore, by extracting a feature point from each surface with different heights in the same vertical plane or horizontal plane in one shooting with the camera for this three-dimensional pattern, the three-dimensional coordinates of the feature point and On the corresponding 2D image It is possible to obtain a large number of coordinates, which makes it possible to perform camera calibration easily, greatly shortening the execution time, accurately, and contribute to highly accurate three-dimensional image measurement. Has a special effect.

The figure which shows the three-dimensional pattern for camera calibration in 1st Embodiment by this invention The figure which shows the feature point employ | adopted for the same three-dimensional pattern ((a) is the figure seen from the front, (b) is the figure which shows the distance from the center of a pattern to each feature point, and the height of a feature point) The figure which shows the condition of the image of the feature point of four corners when the feature point employ | adopted for the same three-dimensional pattern was imaged by the camera The figure which shows the camera calibration using the same three-dimensional pattern The figure which shows the 1st example of a change of the same three-dimensional pattern The figure which shows the 2nd example of a change of the same three-dimensional pattern The figure which shows the 3rd example of a change of the same three-dimensional pattern The figure which shows the 4th example of a change of the same three-dimensional pattern The figure which shows the 5th example of a change of the same three-dimensional pattern The figure which shows the 6th example of a change of the same three-dimensional pattern The figure which shows the 7th example of a change of the same three-dimensional pattern The figure which shows the 8th example of a change of the same three-dimensional pattern The figure which shows the three-dimensional pattern for camera calibration in 2nd Embodiment by this invention The figure which shows the three-dimensional pattern for camera calibration in 3rd Embodiment by this invention The figure which shows the example of a change of the feature point employ | adopted as a three-dimensional pattern in each embodiment The figure which shows the example of a change of the several surface employ | adopted as a three-dimensional pattern in each embodiment ((a) shows the state which shrunk a several surface, (b) shows the state which expanded the several surface. Figure showing The figure which shows an example of the three-dimensional pattern used for the conventional camera calibration The figure which shows an example of the two-dimensional pattern used for the conventional camera calibration

Next, embodiments for carrying out the present invention will be described with reference to the drawings.
FIGS. 1 to 16 each illustrate a camera calibration three-dimensional pattern (hereinafter simply referred to as a three-dimensional pattern) for measuring camera parameters necessary for three-dimensional image measurement using a camera.
In each of these three-dimensional patterns, a plurality of surfaces 1 and 2 are formed with steps in the same vertical plane or horizontal plane. It is basically provided with a feature point 3 whose dimensional coordinates are known.

  Each of these three-dimensional patterns is provided on one surface of a rectangular parallelepiped block or rectangular board having the same size (vertical and horizontal dimensions) as the measurement target area of the object that is the target of the three-dimensional image measurement. The surface is formed. In this case, it is desirable that the block or board is formed of a material that does not expand or contract due to temperature change. Here, a rectangular parallelepiped block B that does not expand or contract due to temperature change is adopted, and the vertical plane of the block is used. A plurality of stepped portions are formed in a concavo-convex shape in a front rectangular surface B1 that forms the shape, and the tips of these stepped portions form a plurality of surfaces 1 and 2. In addition, the back surface and other surfaces of the block B are flat. In the following description, the front surface B1 is referred to as the same vertical surface B1.

FIG. 1 shows a first embodiment. As shown in FIG. 1, in this three-dimensional pattern P1, in particular, the same vertical surface B1 has a surface 1 having a minimum height as a reference surface at the center, and the reference surface 1 around the reference surface 1 A plurality of surfaces whose height is higher than the reference surface 1, in this case, four surfaces 2 (21, 22, 23, 24) are formed radially from the periphery to the periphery.
In this case, the central reference surface 1 is formed in a rectangular shape, and three surfaces 21, 22, and 23 are formed around the reference surface 1 in a rectangular frame shape along the periphery of the reference surface 1. height farther in the circumferential direction are formed stepwise increase from formation same surface 24 height at four corners is the largest of the vertical plane B1 within striking the four corners third stage of surface 23 is in a rectangular shape in each corner Is done.
Further, in this case, the central reference surface 1 and the four surfaces 21, 22, 23, 24 are all formed in a plane and parallel to the same vertical surface B1. Further, the step portions of these four surfaces 21, 22, 23, and 24 (the inner rule surfaces 21S, 22S, 23S, and 24S of the surfaces 21, 22, 23, and 24) are all perpendicular to the same vertical surface B1. Formed.
In this way, each of the plurality of surfaces 1 and 2 has a three-dimensional shape of a step structure that does not shield other surfaces in front view, that is, a surface with a large step does not shield a surface with a small step due to its height. Composed.
The center reference surface 1 and the surrounding surfaces 21, 22, 23, and 24 are respectively arbitrary surfaces, in this case, feature points 3 whose three-dimensional coordinates are known with reference to the center point of the center reference surface 1. Are regularly added. In this case, the feature point 3 is represented by a checkered pattern, and here, a plurality of small check pattern diagrams in which white and black squares are alternately arranged in one square frame are respectively shown on the central reference plane 1. The same vertical plane B1 at a central location, a plurality of locations symmetrically with the center of the central plane 11 as the center of symmetry on each of the surrounding first, third, and fourth sections 21, 22, 23, and 24 of the center. When viewed as a whole, the check marks are regularly assigned in a plurality of arrangements in the vertical direction and the horizontal direction. The number of the feature points 3 may be six or more, but as many as possible are preferable as illustrated.
In this way, the checkered patterns that are the plurality of feature points 3 are attached at different heights. As shown in FIG. 2, the height in the depth direction of the central checkered pattern is the smallest. Comparing the height of any two checkered patterns in the depth direction, the height of the checkered pattern increases as the distance from the center in the radial direction increases. All checkers meet this condition. When this condition is satisfied, the heights of the four corners of the three-dimensional pattern P1 are the highest, and when such a pattern is photographed, an image in which the four corners of the pattern protrude radially as shown in FIG. . Even in such a case, the height of the pattern is limited so that the checkered pattern at the four corners of the pattern has a height that can be included in the image.

FIG. 4 shows camera calibration using the three-dimensional pattern P1. As shown in FIG. 4, even in the camera calibration using the three-dimensional pattern, the CCD camera C is fixed to the shooting site via a frame or the like in the same manner as a general method, and the front of the CCD camera C is displayed. A three-dimensional pattern, in this case, for example, a three-dimensional pattern P1 is installed in front.
In this way, first, the same vertical plane B1 of the three-dimensional pattern P1 is imaged only once by the CCD camera C to generate two-dimensional image data. Next, based on the generated two-dimensional image data, the feature point 3 of the three-dimensional pattern P1, that is, each lattice point of the checkered pattern is extracted, and the two-dimensional coordinates are calculated. In this case, as described above, the three-dimensional pattern P1 has the surface 1 having the minimum height as the reference surface in the center of the same vertical surface B1, and the reference surface 1 is directed around the reference surface 1 from the reference surface 1 to the periphery. A three-dimensional shape with four surfaces 2 (21, 22, 23, 24) that are stepped with respect to the central surface 1 and have a height that is higher than the reference surface 1. Since each of the surfaces 1 and 2 (21, 22, 23, 24) has a feature point 3 with known three-dimensional coordinates with respect to the central surface 1, the same surface of the three-dimensional pattern P1 A large number of feature points from each of the surfaces 1 and 2 (21, 22, 23, 24) having different three-dimensional shapes on the same vertical plane B1, that is, different heights in one shooting with the CCD camera C for B1 3 can be extracted, the 3D coordinates of the feature point 3 and the corresponding 2D image It can be obtained a large number of coordinates. In this case, it is only necessary to obtain image coordinates of at least six feature points 3 that are not on the same plane, but it goes without saying that accurate calibration can be performed with as many as possible. Then, based on the calculated two-dimensional coordinates of each feature point 3 and the three-dimensional position in the world coordinate system known in advance, that is, the three-dimensional coordinates of each feature point 3 in the installation space of the three-dimensional pattern P1. Using a nonlinear least square method program using the Laneburg-Markert method, the internal and external parameters of the CCD camera C and parameters for correcting image distortion are calculated and estimated. The parameters obtained in this way are stored in the CCD camera C or a computer for image analysis.
Usually, in three-dimensional image measurement, a target object is photographed by a camera such as a CCD camera, and three-dimensional analysis of the photographed image is performed based on each parameter of the camera. When this image measurement is performed using the CCD camera C that has been subjected to camera calibration using, for example, the three-dimensional pattern P1, the internal and external parameters of the camera C and parameters for correcting image distortion are used. In addition, the distortion of the image is greatly reduced, and an accurate captured image of the target object with little distortion can be obtained, and accurate three-dimensional analysis of the target object can be performed from the captured image.

As described above, in the three-dimensional pattern P1, a plurality of surfaces 1 and 2 (21, 22, 23, 24) are formed with a step in the same vertical surface B1, and in this case, particularly in the center. Four surfaces 21, 22, having a surface 1 having a minimum height as a reference surface, and radially increasing from the reference surface 1 to the periphery around the reference surface, the height of which increases stepwise from the reference surface 1. 23, 24 is formed as a three-dimensional shape, and the three-dimensional coordinates are known on the central reference surface 1 and the surrounding surfaces 21, 22, 23, 24, respectively, with the central reference surface 1 as a reference. Since the feature point 3 is attached, many features from the surfaces 1, 2, 22, 23, 24 having different heights in the same vertical plane B1 can be captured by the camera once for the three-dimensional pattern P1. Point 3 is extracted, and the three-dimensional coordinates of feature point 3 and 2 corresponding thereto The coordinates of the original image can be obtained a large number, using these coordinates, the camera can be estimated by external parameters and as much as possible small error parameters for correcting the image distortion.
Therefore, according to the three-dimensional pattern P1, the camera calibration can be performed easily and with a significantly reduced execution time, thereby contributing to highly accurate three-dimensional image measurement.
In this case, the feature point 3 is provided on each of the surfaces 1, 22, 22, 23, and 24 with the center surface 1 as a reference, but the feature point 3 with reference to another surface 2 other than the center surface 1. May be provided.
Further, in this case, in the same vertical plane, it has a surface having the minimum height as a reference surface at an arbitrary position including the center, and radially around the reference surface from the reference surface to the periphery. One surface having a height higher than that of the reference surface is formed, and a feature point having a known three-dimensional coordinate may be attached to each surface on the basis of an arbitrary surface. An effect can be produced.

  5 to 12 show modifications of this three-dimensional pattern.

  FIG. 5 shows a first modification. As shown in FIG. 5, in the case of the three-dimensional pattern P1-1, the central surface 1 is formed in a rectangular shape, and the peripheral surface 2 is formed in a rectangular frame shape along the periphery of the central surface 1. It is formed in two steps from the center to the periphery, the inner surface 21 of the peripheral surface 2 protrudes higher than the central surface 1 by a predetermined height, and the outer surface 22 is the inner surface. It protrudes higher than 21 by a predetermined height. In this way, the outermost periphery of the same vertical surface B1 has the same height as the entire surface, and the highest protruding height in the same vertical surface B1.

  FIG. 6 shows a second modification. As shown in FIG. 6, in the case of this three-dimensional pattern P1-2, it has substantially the same configuration as the three-dimensional pattern P1-1 of the first example as a whole, and the dimensional pattern P1-1 of the first example The difference is that the corners of the four corners of the central surface 1 and the surrounding inner and outer surfaces 21 and 22 are rounded (arc-shaped) with R (R).

FIG. 7 shows a third modification. As shown in FIG. 7, in the case of the three-dimensional pattern P1-3, the central surface 1 is formed in a rectangular shape, and the peripheral surface 2 is formed in a rectangular frame shape along the periphery of the central surface 1. The inner surface 21 of the peripheral surface 2 protrudes higher than the central surface 1 by a predetermined height, and the outer surface 22 is the inner surface 21. And the four corners of the outer surface 22 are all the highest in the same vertical plane B1 of the convex surface 24 having a cross-sectional saddle shape. A convex surface 23 having a rectangular cross section is formed between the planar surfaces 24 and is formed to be higher than the inner surface 21 and lower than the convex surface 24 having a bowl-shaped cross section in the same vertical plane B1. 2 of the outer surfaces 22 of the two protrusions protrudes higher than the inner surface 1 by a predetermined height. And, it is protruded higher by a predetermined height than the convex surface 23 convex surface 24 having a rectangular cross section each section hook. In this way, the outermost periphery of the same vertical surface B1 has the same protruding height at which the convex surfaces 24 at the four corners are the highest in the same vertical surface B1, and the convex surfaces at the four corners. Each surface 23 between 24 is lower than the protruding height of each convex surface 24 at the four corners, and higher than the other surfaces in the same vertical plane B1.

  FIG. 8 shows a fourth modification. As shown in FIG. 8, in the case of this three-dimensional pattern P1-4, it has almost the same configuration as the three-dimensional pattern P1-3 of the third example as a whole, and the three-dimensional pattern P1-3 of the third example. The difference is that the corners of the four corners of the central surface 1 and the surrounding inner and outer surfaces 21 and 22 are rounded (arc-shaped) with R (R).

  FIG. 9 shows a fifth modification. As shown in FIG. 9, in the case of this three-dimensional pattern P1-5, the central surface 1 is formed in a cross shape at the center in the same vertical surface B1, and is vertically formed in the horizontal center in the same vertical surface B1. It consists of a combination of a vertical surface 11 extending in a rectangular shape in the direction and a horizontal surface 12 extending in a rectangular shape in the horizontal direction at the center in the vertical direction. In this case, the vertical and horizontal surfaces 11 and 12 are extended to the edge of the same vertical surface B1. Further, the vertical surface 11 is wider than the horizontal surface 12. The peripheral surface 2 is formed in a rectangular shape along the periphery of the central surface 1 and in a two-step shape from the center toward the periphery. Each of the inner surfaces 25 of the peripheral surface 2 has a rectangular cross section and protrudes higher than the central surface 1 by a predetermined height, and the outer surfaces 26 each have a bowl-shaped cross section. It protrudes higher than the surface 21 by a predetermined height. In this way, the outermost periphery of the same vertical surface B1 has the same overall height and the highest protruding height in the same vertical surface B1.

  FIG. 10 shows a sixth modification. As shown in FIG. 10, in the case of this three-dimensional pattern P1-6, it has almost the same configuration as the three-dimensional pattern P1-5 of the fifth example as a whole, and the three-dimensional pattern P1-5 of the fifth example. The difference is that the corners at the four corners of the central planes 11 and 12 and the inner and outer surfaces 25 and 26 are rounded (circular arcs).

  FIG. 11 shows a seventh modification. As shown in FIG. 11, in the case of this three-dimensional pattern P1-7, the central surface 1 is formed in a cross shape in the center in the same vertical surface B1, and is vertically formed in the horizontal center in the same vertical surface B1. It consists of a combination of a vertical surface 13 extending in a rectangular shape in the direction and a horizontal surface 14 extending in a rectangular shape in the horizontal direction at the center in the vertical direction. In this case, each of the vertical and horizontal surfaces 13 and 14 penetrates an inner surface 27 described later to a predetermined position on the peripheral surface in the same vertical plane B1, and here, the inner and outer surfaces 27 are inserted. , 28 to the boundary between. In this case, the vertical surface 13 is wider than the horizontal surface 14. The peripheral surface 2 is formed in a rectangular shape along the periphery of the central surface 1 and in a two-step shape from the center toward the periphery. In this case, each of the inner surfaces 27 of the surrounding surface 2 is a rectangular cross-sectional surface and protrudes higher than the central surface 1 by a predetermined height, and the outer surface 28 is a series of the same height as a whole. The surface protrudes higher than the inner surface 23 by a predetermined height. In this way, the outermost periphery of the same vertical surface B1 has the same overall height and the highest protruding height in the same vertical surface B1.

  FIG. 12 shows an eighth modification. As shown in FIG. 12, in the case of the three-dimensional pattern P1-8, the overall configuration is substantially the same as the three-dimensional pattern P1-7 of the seventh example, and the three-dimensional pattern P1-7 of the seventh example is provided. The difference is that the corners of the four corners of the central planes 13 and 14 and the inner and outer surfaces 27 and 28 are rounded (circular arcs).

  In this way, the plurality of surfaces 1 and 2 in the same vertical surface B1 do not shield other surfaces in front view, that is, the surface having a large step does not shield the surface having a small step due to the height of the surface. It is configured in a three-dimensional shape of a step structure, and feature points 3 are attached to the surfaces 1 and 2. Even in this way, these three-dimensional patterns P1 to P8 can be used in the same manner as in the first embodiment, and the same effects as those in the first embodiment can be obtained.

FIG. 13 shows a second embodiment. As shown in FIG. 13, in the three-dimensional pattern P2, in particular, in the same vertical plane B1, the surface 1 having the maximum height is provided as a reference plane in the center, contrary to the first embodiment. A plurality of surfaces 2 (in this case, three surfaces 21, 22, and 23) having a height lower than that of the reference surface 1 are formed in a step shape radially around the reference surface 1 from the reference surface 1 to the periphery. Is done. In this case, surfaces having the minimum height may be formed at the four corners in the same vertical surface B1. Then, a feature point 3 having a known three-dimensional coordinate is attached to each of these surfaces 1, 2, 22, 22 and 23 with the center surface 1 as a reference.
In this way, the plurality of surfaces 1, 2, 22, and 23 in the same vertical surface B1 do not shield the other surfaces in front view, that is, the surface having a large step has a small step due to the height of the surface. The feature point 3 is attached to each of the surfaces 1, 2, 22, and 23 with a three-dimensional shape having a step structure that does not shield the surface. Even in this case, the same effect as that of the first embodiment can be obtained by using the three-dimensional pattern P2 in the same manner as in the first embodiment.
In this case, the feature points are provided on each surface with the center surface as a reference, but the feature points may be provided on the basis of another surface other than the center surface.
Further, in this case, in the same vertical plane, it has a plane having the maximum height as a reference plane at an arbitrary position including the center, and radially around the reference plane from the reference plane to the periphery. A single surface having a height lower than that of the reference surface may be formed, and a feature point 13 having a known three-dimensional coordinate may be attached to each surface on the basis of an arbitrary surface. The effect of this can be obtained.

FIG. 14 shows a third embodiment. As shown in FIG. 14, in this three-dimensional pattern P3, in particular, in the same vertical plane B1, a reference surface 1 having a minimum height is provided on one side, and the reference surface 1 extends in the direction of the other side. A plurality of surfaces 2 (21, 22, 23, 24, 25, 26) whose height is higher than that of the reference surface 1 as they move away from the reference surface 1 in the direction toward the other side are formed in parallel. Then, a feature point 3 having a known three-dimensional coordinate is attached to each of these surfaces 1, 2, 22, 23, 24, 25, and 26 with reference to the reference surface 1 on one side.
In this way, the plurality of surfaces 1, 2, 22, 23, 24, 25, and 26 in the same vertical surface B1 do not shield the other surfaces in front view, that is, have a large step. Each surface 1, 2, 22, 23, 24, 25, and 26 is provided with a feature point 3 in a three-dimensional shape having a step structure that does not shield a surface with a small step depending on the height. Even in this case, the same effect as that of the first embodiment can be obtained by using this three-dimensional pattern P3 in the same manner as in the first embodiment.
In this case, the feature points are provided on each surface with reference to the reference surface on one side, but the feature points may be provided on the basis of another surface other than the surface on one side.
In this case, in the same vertical plane, one end portion has a reference surface having a minimum height, and is parallel to the other end portion direction from the reference surface and away from the reference surface toward the other end portion. A plurality of surfaces whose height is higher than that of the reference surface are formed according to the above, and each of these surfaces is provided with a feature point whose three-dimensional coordinates are known on the basis of the reference surface at one end or another surface. Even if it does in this way, the effect similar to the above can be acquired.

Furthermore, as another embodiment, although not shown in the drawings, the same vertical plane has a reference plane having a minimum or maximum height at the center in the vertical direction or the horizontal direction, and outward from the reference plane. A plurality of surfaces are formed in parallel with each other so that the height protruding from the reference surface increases or decreases as the distance from the reference surface increases. The three-dimensional coordinates are known based on the reference surface or other surfaces. Various feature points may be attached. In this way, the plurality of surfaces within the same vertical surface do not shield the other surfaces in front view, that is, the step structure 3 in which the surface having a large step does not shield the surface having a small step due to the height of the surface. It may be configured in a dimensional shape, and feature points may be attached to each surface. Even in this way, the same effects as described above can be achieved.
In this case, in the same vertical plane, the reference plane has a minimum or maximum height in the center in the vertical or horizontal direction, and is higher than the reference plane in parallel from the reference plane to the outside. One surface that increases or decreases may be formed, and a feature point having a known three-dimensional coordinate may be attached on the basis of the reference surface or another surface. Can be obtained.

In each of the above embodiments, all of the plurality of surfaces are illustrated as being formed in parallel to the same vertical surface, but all or some of the plurality of surfaces are parallel to the same vertical surface. Alternatively, they may be formed non-parallel (for example, obliquely).
In each of the above embodiments, all of the plurality of surfaces are illustrated as being formed in a planar shape. However, all or a part of the plurality of surfaces is planar or non-planar (for example, a curved surface or an uneven shape). Etc.).
Further, in each of the above embodiments, all of the stepped portions of the plurality of surfaces are illustrated as being formed at right angles to the same vertical surface, but all or some of the stepped portions of the plurality of surfaces are the same. It may be formed at right angles or non-right angles (for example, oblique) with respect to the vertical plane. When the step portion is formed obliquely, a feature point may be attached to the oblique step portion.
Furthermore, although the outer shape of each surface is substantially rectangular, the outer shape of each surface may be a circle or an ellipse, or another polygon such as a triangle or a pentagon.
Furthermore, in each of the above embodiments, the feature points are exemplified as regularly arranged on a plurality of surfaces, but as shown in FIG. They may be arranged irregularly such as vertically and horizontally asymmetric.
Even if it does in this way, the effect similar to the above can be acquired.

  In each of the above embodiments, the three-dimensional pattern is illustrated as being formed on one surface of a rectangular or cubic block or a rectangular board. However, as illustrated in FIG. 1 and 2 can be separated at predetermined positions so that the block or board can be divided into a plurality of small blocks (or small boards) SB, and each small block (or small board) SB is a connecting member 4 such as a rod part. The plurality of surfaces 1 and 2 may be configured to be expandable and contractible two-dimensionally or three-dimensionally. In this case, the separation surface of each small block (or small board) SB may be a straight line or a curve, and the arrangement direction of the connecting member 4 is also arbitrary. However, the three-dimensional coordinates of the checkered pattern after reconstruction are made known. By doing in this way, even when the object of image measurement becomes large, a common three-dimensional pattern can be used similarly, and there can exist an effect similar to the above.

In each of the above embodiments, each of the three-dimensional patterns is formed by forming a plurality of steps in the same vertical plane, that is, in the vertical plane of a rectangular parallelepiped block or a rectangular board. Although illustrated as an example, a plurality of surfaces may be formed with steps in the same horizontal plane such as a rectangular parallelepiped block or a rectangular board, and feature points with known three-dimensional coordinates may be attached. Even in this way, the same effects as described above can be obtained.
Furthermore, each three-dimensional pattern is a single rectangular parallelepiped block or board, and a plurality of surfaces are formed on one surface. In this case, the entire outer shape may be a circle or an ellipse. Other polygons such as triangles and pentagons are also possible.
Even if it does in this way, there can exist an effect similar to the above.

  There is room for change in the design of this three-dimensional pattern. In this case, however, the basic configuration described above of this three-dimensional pattern, that is, a plurality of surfaces are stepped in the same vertical plane or horizontal plane. A plurality of surfaces are each configured with a step structure that does not shield other surfaces in front view or plan view, and each surface has a known three-dimensional coordinate on the basis of an arbitrary surface. As long as the point is provided, the same effects as those of the above-described embodiments can be achieved.

P1-P3 3D pattern B block SB Small block B1 Front surface (same vertical surface)
1 Center plane (center reference plane)
DESCRIPTION OF SYMBOLS 11 Longitudinal surface 12 Lateral surface 13 Longitudinal surface 14 Lateral surface 2 Surface 21 Inner surface 22 Outer surface 23 Convex surface of rectangular section 24 Convex surface 25 of cross section Surface 26 Outer surface 27 Inner surface 28 Outer surface 3 Feature point 4 Connecting member C CCD camera

Claims (7)

A camera calibration 3D pattern for measuring camera parameters necessary for 3D image measurement using a camera,
In the same vertical plane or horizontal plane, a plane having a minimum or maximum height as a reference plane at any position including the center, radially around the reference plane from the reference plane to the periphery, and A plurality of surfaces that increase or decrease in height as they move away from the reference surface in the circumferential direction are formed, and four independent regions each including each corner of the outermost four corners away from the reference surface have heights The largest or smallest surface is formed,
Each of the plurality of surfaces including the surface having the maximum or minimum height includes feature points with known three-dimensional coordinates with respect to the arbitrary surface.
A three-dimensional pattern for camera calibration.   The three-dimensional pattern for camera calibration according to claim 1, wherein all or some of the plurality of surfaces are formed parallel or non-parallel to the same vertical surface or horizontal surface.   3. The camera calibration three-dimensional pattern according to claim 1, wherein all or some of the plurality of surfaces are formed in a planar shape or a non-planar shape.   The three-dimensional pattern for camera calibration according to any one of claims 1 to 3, wherein all or part of the stepped portions of the plurality of surfaces are formed at right angles or non-right angles with respect to the same vertical surface or horizontal plane.   The three-dimensional pattern for camera calibration according to claim 1, wherein the feature points are regularly or irregularly arranged on a plurality of surfaces.   6. The camera calibration three-dimensional pattern according to claim 1, wherein the plurality of surfaces are formed on one surface of a rectangular parallelepiped or cubic block or a rectangular board.   Blocks or boards can be divided into a plurality of small blocks or small boards so that a plurality of surfaces can be separated at predetermined positions, and a plurality of surfaces can be expanded and contracted two-dimensionally or three-dimensionally. The three-dimensional pattern for camera calibration according to any one of claims 1 to 6.

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