JP2003139518A - Image input optical system and three dimensional shape measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image input optical system and a three dimensional shape measuring device capable of picking up images of a subject from three or more different view points by one shooting, and facilitating the acquisition of an image where a measuring process of a three dimensional shape of an object to be measured is easy. SOLUTION: The image input optical system inputting three or more images in one image pickup element is characterized in that it is provided with one image pickup lens 12 forming an image on the image pickup element, a first dividing mirror 13 having at least two reflecting faces and dividing an angle of view of the image pickup lens, and a second dividing mirror 14 having at least two reflecting faces and further dividing the angle of view divided by the first dividing mirror. The three dimensional shape measuring device is characterized in that it uses the optical system.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image input optical system for projecting an image of a subject on an image pickup device and a measuring device for measuring the shape of the subject using the input image.

[0002]

2. Description of the Related Art A stereo camera is an example of inputting a plurality of images of a subject into one image pickup device. JP 200
A stereo camera is disclosed in 0-227332.
This uses two image pickup lenses to input a stereo image to one image pickup element. However, a sufficient parallax cannot be obtained only by providing the two image pickup lenses in front of the image pickup device, and therefore, a mirror is provided to widen the distance between the optical axes of the respective image pickup lenses (FIG. 5). . However, since two image pickup lenses are arranged immediately before one image pickup element, a telecentric image pickup lens cannot be used, which is not practical.

Optical techniques are also used for three-dimensional image measurement and three-dimensional modeling. Japanese Unexamined Patent Publication No. 7-91927 discloses a three-dimensional measuring device by a stereo method. Figure 6
As shown in, the stripe pattern is projected on the subject 90, and the subject 91 is imaged by the two cameras (92, 93).
The three-dimensional structure of the subject is measured based on the principle of triangulation from the bending of the photographed stripe pattern. In this conventional example, the period of the projected stripe pattern is changed to obtain a plurality of sheets and the measurement space density is increased. Moreover, the accuracy is improved by using two cameras. A method of measuring a three-dimensional shape using only a stereo image without projecting a stripe pattern has also been proposed (Japanese Patent Laid-Open No. 8-201023). Multiple images are taken of the subject from different positions, corresponding points are found on the obtained images, and the distance to the corresponding points is measured by the principle of triangulation. This method has a drawback in that it is difficult to find corresponding points, but it is possible to obtain a high-density range image at the pixel level.

[0004]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
In the case of 27332, since two image pickup lenses are used when inputting into one image pickup element, the light ray entering the image pickup element cannot be made telecentric. A color filter is used for the color solid-state image sensor that is normally used. To ensure sufficient sensitivity of the image sensor,
It is necessary to make the light rays incident on the image pickup surface as perpendicularly as possible, that is, in a telecentric manner. Therefore, the above optical system is not preferable when a color image pickup device is used.

In the case of the above-mentioned Japanese Patent Laid-Open No. 7-91927,
It is a shape seen from a certain direction even if it is called a three-dimensional shape because it is imaged by two cameras. Therefore, the shape of the subject from all directions, that is, the three-dimensional shape of the entire subject cannot be measured. Japanese Unexamined Patent Publication No. 8-201023 has the same drawback. A method has been proposed in which the subject is placed on a rotating table, the shape information is obtained by the above method while rotating, and the shape of the entire object is measured by combining them. It has the drawback that it cannot capture a momentary event such as a moving subject.

The present invention pays attention to these points, and an image input optical system capable of acquiring images of a subject from a plurality of directions with one camera and a three-dimensional shape measurement of the subject using the optical system. A three-dimensional shape measuring device that can be photographed once.

[0007]

In order to solve the above-mentioned problems, according to the present invention, (1) in an optical system for inputting three or more images into one image pickup device, an image is formed on the image pickup device. Has one imaging lens and a plurality of reflective surfaces,
An image input optical system comprising: an angle-of-view dividing unit that divides an angle of view (shooting range) imaged through the imaging lens.

Further, according to the present invention, (2) the view angle dividing means has at least two reflecting surfaces and divides the view angle (shooting range) of the taking lens by the first view angle dividing means ( A prism mirror) and at least two reflecting surfaces, and second view angle dividing means (prism mirror) for further dividing the view angle (shooting range) divided by each of the first image dividing means (prism mirror). ) And are provided, the image input optical system as described in (1) is provided.

Further, according to the present invention, (3) the angle-of-view dividing means includes a light ray which is a principal ray of the imaging lens and is symmetric with respect to the optical axis guided to the angle-of-view dividing means. Of the two angled rays, the two principal rays located at a position symmetrical to the plane formed by the optical axis and the edge where the two reflecting surfaces of the angle of view dividing means intersect are two rays passing through the angle of view dividing means. (1) and (2), characterized in that the principal ray passing through the center of the angle of view divided by the angle of view dividing means is guided to the subsequent optical means as a new optical axis. An image input optical system is provided.

Further, according to the present invention, (4) one image pickup lens for forming an image on the image pickup device and two reflecting surfaces for dividing an angle of view (photographing range) imaged through the lens into two. Both, a first split mirror (prism mirror) and a first split mirror (prism mirror) arranged such that a ridge dividing the two reflection surfaces is included in a plane orthogonal to the optical axis of the imaging lens. The angle of view (shooting range) bisected by 2 is further divided into two, and a ridge that divides the two reflection surfaces is arranged so as to be parallel to the optical axis of the imaging lens. Two split mirrors (prism mirrors) and splits by the first and second split mirrors (prism mirrors) on a line radially extending on the plane from the intersection of the optical axis and a plane perpendicular to the optical axis. Angle of view The first reflection mirror arranged so that the chief ray in the (shooting range) is introduced, and the chief ray passing through the center of the divided field angle (shooting range) via the first reflecting mirror are imaged as described above. An image input optical system is provided, comprising: a second reflecting mirror that bends toward an extension of the optical axis of the lens.

According to the present invention, (5) (1),
There is provided a three-dimensional shape measuring apparatus for measuring a three-dimensional solid shape of a subject from a plurality of images obtained by the image input optical system according to (2), (3) or (4).

Further, according to the present invention, (6) the corresponding points (regions) of the subject are specified in each of the plurality of images, and the three-dimensional shape of the subject is obtained from the positional relationship thereof. A three-dimensional shape measuring device is provided.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a first embodiment of the present invention. Imaging device (CCD) 11 and lens 1
An ordinary camera 10 is constituted by 2, and the angle of view of this camera, that is, the imaging range is determined by the focal length of the lens 12 and the size of the CCD 11. Mirror 13 (mirror A)
Is an isosceles triangular prism having two reflecting surfaces 13-1 and 13-2 and having its edge as 13-3, and its edge 13-3.
The angle of view (shooting range) of the camera 10 is divided into two at the boundary.

The two mirrors 14 (mirror B) are
The mirrors 13 (mirror A) are arranged symmetrically. This mirror 14 (mirror B) is a prism mirror of the same kind as the mirror 13 (mirror A), and has a reflecting surface 14-
1 and 14-2 and a ridge 14-3, but at least their directions are different. (The mirror 13 and the mirror 14 are
It need not be dimensionally identical. )In particular,
The direction of the ridge 14-3 of the mirror 14 (mirror B) is the mirror 1.
3 (mirror A) is perpendicular to the edge 13-3, that is, parallel to the optical axis 20 of the lens 12. With this arrangement, the mirror 14 (mirror B) becomes
The angle of view bisected by 3 (mirror A) is further bisected. That is, the angle-of-view dividing unit (imaging range dividing unit) configured by the mirror 13 and the mirror 14 divides the angle of view (imaging range) of the camera 10 into four equal parts.

By the way, as a more detailed arrangement condition,
In order to divide the angle of view (imaging range) by the mirror 13 (mirror A), “the optical axis of the lens 12 (the optical axis guided to the mirror 13)” and “the two positions symmetrical to the optical axis of the lens 12” Of the two principal rays of the mirror 13 (mirror A), which are symmetrical with respect to the plane formed by the ridge 13-3 of the mirror 13 (mirror A) and the optical axis 12 of the lens, So that the “light rays passing through the reflecting surfaces (13-1 and 13-2)” are included in one plane.
Lens 12, ridge 13-3 and two reflecting surfaces 13-1, 1
3-2 is arranged. Further, the chief ray of the lens 12 passing through the center of the angle of view divided by the split mirror 13 (mirror A) is guided to the subsequent optical means, in this case, the mirror 14 as a new optical axis. Since this arrangement is adopted, the CCD 1 is caused by the mirror 13 (mirror A).
No rotation of the image formed on 1 occurs.

The same idea is applied when the angle of view (imaging range) is further divided into two parts by the mirror 14 (mirror B).
That is, as a result of the angle of view being divided by the mirror 13 (mirror A), the new optical axis set is treated as the optical axis guided to the mirror 14 (mirror B). The "optical axis guided to the mirror 14" and the "edge 14-of the mirror 14 (mirror B) of the two principal rays symmetrical to the optical axis guided to the mirror 14-
3 and the two principal rays at positions symmetrical to the plane formed by the optical axis guided to the mirror 14 pass through two different reflecting surfaces (14-1 and 14-2) of the mirror 14 (mirror B). So that the light beam that has passed through is included in one plane,
With respect to the mirror 13 (mirror A), the ridge 14-3 of the mirror 14 (mirror B) and the two reflecting surfaces 14-1 and 14-2.
Are placed. Therefore, like the arrangement of the mirror 13,
Image rotation due to the placement of the mirror 14 does not occur.
Further, the principal ray passing through the center of the angle of view divided by the mirror 14 is guided to the next optical means, that is, the mirror 15 (mirror C) as a new optical axis.

Next, the arrangement of the mirror 15 (mirror C) will be described. The mirror 15 (mirror C) passes the chief ray 17 passing through the center of the angle of view divided into four by the mirror 13 (mirror A) and the mirror 14 (mirror B), to the optical axis 2 of the lens 12.
It is arranged so that a straight line extending radially from the intersection point 21 of the plane orthogonal to 0 and the plane orthogonal to the optical axis 20 coincides (is introduced).

Based on this, the mirror 13 (mirror A)
Also, a total of four mirrors 15 (mirror C) that respectively reflect the angle of view divided into four by the mirror 15 (mirror B) are arranged symmetrically with respect to the mirror 13 (mirror A).
At this time, preferably each mirror 1 from the intersection 21
The straight lines extending radially in 5 are preferably 90 degrees apart. This is to acquire images from a plurality of viewpoints at equal intervals over the entire circumference of the subject.

Further, the mirror 16 (mirror D) is arranged so as to guide the principal ray 17 passing through the center of the four-divided field angle to a linear point 22 extending the optical axis 20 of the lens 12. In other words, the light ray from the subject 30 is reflected, guided to the above-mentioned radial straight line, and guided to the mirror 15 (mirror C) so that the image of the subject 30 can be captured. That is, the mirror 16 (mirror D) is arranged so as to guide the light beam from the light point existing on the point 22 obtained by extending the optical axis 20 of the lens 12 to the mirror 15 (mirror C). Based on this, the other three mirrors D are also arranged.

The optical system arranged as described above suppresses unnecessary rotation of the image to be picked up. Therefore, as shown in FIG. It is projected and the image pickup surface can be used effectively. That is, a rectangular image can be disposed on the light receiving surface of the image pickup element, which is usually rectangular, without waste.

On the other hand, if such consideration is neglected, the subject rotates as shown in FIG. 3 and the image pickup surface cannot be effectively used, and when the shape of the subject is obtained from the image, corresponding points of the subject are obtained. The image processing that takes is more complicated, and extra processing is required for the corresponding point search.

Next, a method of identifying corresponding points between a plurality of images obtained by using the above optical system will be described. As a method of identifying the corresponding points of the respective subject images of the four images, a method of taking a correlation is known. For example, as shown in FIG. 4, a window is set, the difference between the images in the window is calculated, and the point of coincidence, that is, the point of zero is determined as the coincidence point. In reality, it does not become zero due to image deformation, noise, etc., so the point where the minimum value is obtained is obtained.

That is, image A: g (x, y), image B:
As h (x, y), the correlation value S is

[0024]

[Equation 1]

It is expressed as Here, m is the amount by which the image is shifted when calculating the correlation, and in this case, the window range is 2m + 1.
Is. When the correlation value S becomes the minimum, it means that the images match and the corresponding points are obtained.
Is the value of.

By the way, it is preferable that the images to be correlated are images viewed from the same direction, but the images obtained from the four directions have different viewing angles by about 90 degrees. Therefore, the two images having the correlation are projected in the same direction and corrected (by image processing) and then used. Such corresponding points are calculated over the entire subject, and the shape of the subject is obtained from the positional relationship of the corresponding points. Then, after determining the corresponding points, the three-dimensional shape of the entire subject can be measured by using the parallax of each corresponding point to acquire the three-dimensional information of the subject for each corresponding point.

[0027]

According to the present invention, an image input capable of telecentrically forming an image on one image pickup device and taking images from three or more viewpoints arranged on one image pickup device. An optical system and a three-dimensional shape measuring apparatus using the same are provided.

That is, the optical system and the apparatus according to the present invention have high sensitivity and are moving in motion (measuring object).
It is possible to easily obtain an image that can easily handle the three-dimensional shape of the measurement target.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an image input optical system according to the present invention.

FIG. 2 is a diagram showing an image obtained by the image input optical system according to the present invention.

FIG. 3 is a diagram showing an example of an image captured by an inappropriate image input optical system.

FIG. 4 is a diagram illustrating the principle of the corresponding point identifying method adopted in the three-dimensional shape measuring apparatus according to the present invention.

FIG. 5 is a diagram showing a first conventional example.

FIG. 6 is a diagram showing a second conventional example.

[Explanation of symbols]

10 cameras 11 Image sensor (CCD) 12 lenses 13 Mirror A (split mirror) 13-1 First reflective surface 13-2 Second reflective surface 13-3 Ridge 14 Mirror B (split mirror) 14-1 First reflective surface 14-2 Second reflective surface 14-3 Ridge 15 Mirror C (reflection mirror) 16 Mirror D (reflection mirror) 17 Principal ray passing through the center of the four-divided angle of view 20 optical axis 21 The intersection of the optical axis and the plane perpendicular to the optical axis 22 Assumed light spot position on a straight line extending the optical axis 23 Eye position 30 subjects

Claims (6)

[Claims] 1. An optical system for inputting three or more images to one image pickup device, which has one image pickup lens for forming an image on the image pickup device and a plurality of reflecting surfaces, and images through the image pickup lens. An image input optical system, comprising: 2. The angle-of-view dividing means has at least two reflecting surfaces, and has a first angle-of-view dividing means for dividing an angle of view of the photographing lens and at least two reflecting surfaces. The image input optical system according to claim 1, further comprising a second angle-of-view dividing unit that further divides the angle of view divided by one angle-of-view dividing unit. 3. The angle-of-view splitting means includes a light ray which is a principal ray of the imaging lens and which is symmetric with respect to the optical axis guided to the angle-of-view splitting means. Two principal rays at a position symmetrical to the plane formed by the optical axis and the edge where the two reflecting surfaces intersect, and two rays that have passed through the angle-of-view dividing means are included in one plane, and 3. The image input optical system according to claim 1, wherein the principal ray passing through the center of the angle of view divided by the angle-of-view dividing unit is guided to a subsequent optical unit as a new optical axis. 4. A plane having one image pickup lens for forming an image on an image pickup device and two reflecting surfaces so as to divide an angle of view picked up by the lens into two, and a plane orthogonal to an optical axis of the image pickup lens. A first split mirror arranged so as to include a ridge separating the two reflective surfaces, and two reflective surfaces for further splitting the angle of view bisected by the first split mirror. A second split mirror in which a ridge that separates the two reflecting surfaces is arranged so as to be parallel to the optical axis of the imaging lens, and on the plane from the intersection of the optical axis and a plane perpendicular to the optical axis. On a line that extends radially,
A first reflection mirror arranged so that a chief ray passing through the center of the angle of view divided by the first and second split mirrors is introduced, and the split angle of view via the first reflection mirror An image input optical system, comprising: a second reflection mirror that bends a chief ray passing through the center of the image pickup lens toward an extension line of the optical axis of the imaging lens. 5. A three-dimensional shape measuring device for measuring a three-dimensional solid shape of a subject from a plurality of images obtained by the image input optical system according to claim 1. 6. A corresponding point of a subject in each of a plurality of images
The three-dimensional shape measuring apparatus according to claim 5, wherein the (part) is specified, and the three-dimensional shape of the subject is obtained from the positional relationship.