JPH04181107A - Method and device for recognizing three-dimensional shape - Google Patents

Abstract

PURPOSE:To enable an imaginary image to be eliminated and a real image to be extracted positively by rotating a slit light generator, comparing image coordinates of a reflection light which is taken before and after rotation, and by extracting those where both image coordinates match or have less deviation. CONSTITUTION:Although there is not great change between a real image position R of a reflection light which is taken before rotating a slit light generator 1 and a real image position R' after rotation, deviation between positions G1 and G2 of imaginary images I and II before rotating the generator 1 and those G1' and G2' after rotation becomes large. These images which are taken by a camera 4 are processed by an image taking device 5 and a coordinates operation device 6 and the coordinates of the obtained image are memorized 7. Then, both coordinates are compared by an imaginary image judging device 8 and an image with less deviation of coordinates is determined to be a real image, while that with much deviation is determined to be an imaginary image. Therefore, even if an object to be measured 9 consists of a material with a large reflection factor and a double reflection occurs due to a sharp slanted surface, the imaginary image can be eliminated positively and a three- dimensional shape can be recognized accurately.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a three-dimensional shape recognition method and apparatus using a light sectioning method, and particularly to a method for reliably detecting and removing virtual images.

<Prior Art> In the field of machine tools, it may be necessary to recognize three-dimensional shapes in order to perform copying or to prevent collisions, or for mold processing equipment.

Optical sectioning is one method of non-contact shape recognition. This method involves irradiating a measurement object with slit light and determining the coordinates of the measurement object from the diffusely reflected image.

A conventional three-dimensional shape recognition device using this optical cutting method is shown in FIG. As shown in the figure, a slit light generator 1 is suspended above the object to be measured 9, and the slit light generator 1 irradiates the object to be measured 9 with slit light 2 from vertically above. The slit light generator 1 is movable in a direction perpendicular to the parallel direction of the slit light 2 by a mechanism not shown.

On the other hand, the camera 4 is installed diagonally above the measurement target 9,
An optical image formed by irradiation with the slit light 2 is photographed. Image data corresponding to the image taken by this camera 4 is captured by an image capturing device 5, and the image data is computed by a coordinate computing device 6 so that the shape of the object to be measured 9 can be recognized.

The method of calculating coordinates by the coordinate calculator 6 is shown in Fig. 3(a) (
b) (C) (Explain with reference to dl. However, as shown in Figure 3 (a) and (b), the coordinate axes are horizontal plane x
−X plane, and the vertical direction is the two axis direction. Also,
The slit light 2 is irradiated in two directions, and the camera 4 is observed in an obliquely upward direction in the y-axis direction (an angle of θ from the Z-axis). In other words, the angle between the irradiation direction of the slit light 2 and the optical axis of the camera 4 is θ.

As shown in FIG. 3(C)(d), the slit light 2
Since it coincides with the −X plane, the slit light 2 is expressed by the following formula %. Furthermore, the magnification M at the coordinate origin O, which is a distance from the lens center 0° of the camera 4, is expressed by the following formula.

However, A@B o is the coordinate origin, that is, the X direction in the distance, and the radiation in the screen where the radiation A and B viewed from the X direction are imaged.

Here, as shown in Figure 4, the coordinates in the image are α
, β, the photographing direction on the y-X plane corresponding to these coordinates is expressed by the following formula.

By substituting the above equation (1) into the above equation (3), the two-axis coordinates of the cutting line of the slit light can be found.

Similarly, the X coordinate of the cutting line of the slit light is determined as follows.

In this way, by calculating the two coordinates and the X coordinate using the formula +41 (51), and performing this calculation on the entire object to be measured, the three-dimensional shape can be recognized.

<Problems to be Solved by the Invention> As described above, in the three-dimensional shape recognition method using the light cutting method, the slit light 2 is irradiated onto the measurement object 9, the diffusely reflected light is imaged by the camera 4, and the image is This is to find the coordinates of the object to be measured, but depending on the material and shape of the object to be measured 9, specularly reflected light may be observed, so a virtual image may be observed in addition to the real image, or the virtual image may be more visible than the real image. may be strongly observed.

For example, if the measurement object 9 is made of a material with high reflectance and has a steep slope as shown in FIGS. 5(a) and 5(b), the slit light will be specularly reflected on this steep slope, and the light will be diffusely reflected on other surfaces. , the virtual image 15 due to this diffused reflection may be captured by the camera 4 as the real image 11, and the coordinates may be calculated incorrectly.

In order to solve this problem, conventionally, as shown in Fig. 6, dual cameras 4 and 10 are provided, and the coordinates of images taken by these cameras 4 and 10 are determined and compared. I was doing it. When compared in this way, the coordinates R, , Rb obtained from the real image 11 match each other, but
The coordinates G, , G, obtained from the coordinates G, , G, have different values. It was decided to use this to distinguish between real images and virtual images.

However, this method focuses on the fact that the real image 11 exists within the slit light plane, but the virtual image 15 does not exist within the slit light plane, as shown in FIG. Since this method uses different viewpoints of the camera 4 and IO, there is a problem that the virtual image cannot be completely removed in the case of multiple reflections.

For example, as shown in FIG. 7, the slit light 2 specularly reflected by the surface ABCD is diffusely reflected by the surface CDEF and becomes a virtual image ■.Since the surface ABCD is a mirror, this virtual image I becomes the virtual image ■ by the surface ABCD.
It may appear as.

In this case, the virtual image (2) is observed within the slit light plane as follows due to the mirror image principle.

That is, as shown in FIG. 8, the slit light 2 is projected from the T direction vertically above, is specularly reflected at a point R on the surface ABCD, and is diffusely reflected at a point G1 on the surface CDEF to form a virtual image (2). The following formula holds.

, <TRA=ZG, RC...(6) Here, since the plane ABCD becomes a mirror, the virtual image ■ is the plane ABC
If a virtual image ■ appears on D and its position is G, then the position G1 of the virtual image ■ and the position G2 of the virtual image ■ are symmetrical with respect to the line segment AC.

Also, if P is the intersection of the line segment connecting the position G of virtual image I and the position G of virtual image ■ and the extension line of line segment AC, then ΔRG,
P, ΔRG, and P are all right triangles.

Therefore, /G,PA=/GIPA Also, GtP=/GIP.

Since PR=PR (common), ΔRG, Pmi ΔRG, P...cost η, that is, /GtRC=/CzRC,', l T RA = l G t RC,
/TRA and l G t RC are in a diagonal relationship with each other.

In other words, point G becomes a point on TR and exists within the slit light plane.

However, the conventional virtual image determination method can only determine when the virtual image does not exist within the slit light plane, and cannot eliminate the virtual image (2) caused by double reflection, such as at point G.

The present invention has been made in view of the above-mentioned prior art.
It is an object of the present invention to provide a three-dimensional shape recognition method and apparatus that can reliably detect and remove virtual images in three-dimensional shape recognition using a light cutting method.

<Means for Solving the Problems> The configuration of the three-dimensional shape recognition method of the present invention that achieves the above object is to irradiate a slit light from a slit light generator toward an object to be measured, and to emit slit light from the object to be measured. The reflected light of the light is photographed with a camera, the reflected light photographed with the camera is image-processed to obtain image coordinates, and each image coordinate, the coordinate of the position of the slit light, the angle formed by the slit light and the optical axis of the camera, In a method for recognizing the three-dimensional shape of a measurement target based on the specifications of a camera lens, the illumination angle of the slit light with respect to the measurement target is changed by rotating the slit light generator, and the slit light is generated. The present invention is characterized in that the image coordinates of the reflected light photographed by the camera before and after the rotation of the vessel are obtained, the two are compared, and an image whose coordinates match or whose deviation is small is extracted.

The three-dimensional shape recognition device of the present invention that achieves the above object includes a slit light generator that irradiates a slit light toward an object to be measured, and a camera that photographs the reflected light of the slit light from the object to be measured. Then, each reflected light photographed by the camera is image-processed to obtain each image coordinate, and each image coordinate, the coordinate of the position of the slit light, the angle formed by the slit light and the optical axis of the camera, and the specifications of the camera lens are calculated. A three-dimensional shape recognition device having an image processing means for detecting the shape of an object to be measured based on the slit light generator; a coordinate memory for storing image coordinates obtained by processing by the image processing means; and image coordinates obtained by photographing with the camera after rotation of the slit light generator and processing by the image processing means and the coordinate memory. The present invention is characterized by having a coordinate discriminator that compares the image coordinates stored in the image coordinates and determines that the coordinates of both images match or have a small difference as a real image.

<Operation> When a slit light beam is irradiated from a certain angle onto a measuring object with high reflectance, the specularly reflected light forms a virtual image, and that virtual image is mirrored on another surface to form another virtual image. There is.

When multiple reflections occur in this way, when the slit light generator is rotated, the coordinates of the real image hardly change, whereas the virtual image shifts significantly even if it is within the slit light plane.

Therefore, the image coordinates before and after rotating the slit light generator to change the irradiation angle with respect to the measurement object are calculated and compared, and the image where the coordinates of both screens match or whose deviation is small is determined to be a real image and extracted. On the other hand, those that do not match or have a large difference are determined to be virtual images and are removed.

<Examples> The present invention will be described in detail below with reference to examples shown in the drawings.

FIG. 1 shows an embodiment of the present invention. As shown in the figure, a slit light generator 1 is supported by a slit light rotator 3 above the object to be measured 9 .

The slit light generator 1 irradiates the slit light 2 onto the measurement target 9 from approximately vertically above, and the irradiation angle to the measurement target 9 is determined by the slit light generator 1 using the slit light rotator 3. It changes by rotating. - On the other hand, a camera 4 is installed obliquely above the measurement target 9 to observe the reflected light.

Image data corresponding to the image taken by this camera 4 is captured by an image capturing device 5, and the image data is computed by a coordinate computing device 6 so that the shape of the object to be measured 9 can be recognized.

Therefore, before and after the slit light generator 1 is rotated by the slit light rotator 3, the coordinates of the image taken by the camera 4 and obtained by image processing by the image capture device 5 and the seat S calculator 6 will be different. .

For example, as shown in an exaggerated manner in FIG. 9(a), the position of the real image before rotating the slit light generator I is R1, the position of virtual image ■ is G7, and the position of virtual image ■ is G! As shown in the same figure (b), after rotating the slit light generator 1, the position of the real image is R', the position of the virtual image ■ is 01', and the position of the virtual image ■ is G.
, ', the positions of the real images R and R' do not change much before and after the point of the slit light generator, whereas the positions of the virtual images ■, ■ are G3, G + ', G t,
The deviation of G t' is inevitably larger.

The result calculated by the coordinate calculator 6 is input to the coordinate memory 7.

The coordinate calculator 6 stores the coordinates of an image taken by the camera 4 before the rotation of the slit light generator 1 and processed by the image capture device 5 and the coordinate calculator 6.

Furthermore, the coordinates of the image stored in the image storage 7 are input to the virtual image discriminator 8, and the coordinates of the image captured by the camera 4 after the rotation of the slit light generator 1 are input to the virtual image discriminator 8, and the coordinates of the image are input to the virtual image discriminator 8. The coordinates of the image obtained by image processing in step 6 are input.

The virtual image discriminator 8 compares the coordinates of both images, and determines that an image with a small deviation in both coordinates is a real image, and an image with a large deviation as a virtual image.

For example, as shown in FIG. 9(a) (bl), before and after the rotation of the slit light generator l, the coordinate positions R,
While R' is almost unchanged, the coordinate positions G3, G+', and G-1G2' of the virtual images (2) and (2) are significantly shifted compared to that.

Therefore, by comparing the coordinates, it is determined that the virtual images (1) and (4) are virtual images, and only the real images can be extracted and used for three-dimensional shape recognition.

In this way, in the present invention, the slit light generator l is rotated to change the irradiation angle with respect to the measurement object 9, and the coordinate position of the real image hardly changes before and after the change.
Taking advantage of the fact that the coordinate position of a virtual image changes greatly, it is possible to distinguish between a real image and a virtual image, and extract only the real image.

Therefore, even if double reflection occurs, such as when the measurement object 9 is made of a material with a high reflectance and has a steep slope, the virtual image can be reliably removed and accurate three-dimensional shape recognition can be performed.

In the above embodiment, the position of the real image was slightly shifted by rotating the slit light generator l, but as a result of calculation processing, the rotation of the slit light generator l was determined to such an extent that no change in the position of the real image was measured. The angle may be made very small.

<Effects of the Invention> As specifically explained above based on the embodiments, the present invention distinguishes between a real image and a virtual image by changing the irradiation angle with respect to the object to be measured by rotating the slit light generator. Even if multiple reflections occur on the object to be measured, the virtual image can be reliably removed and the real image extracted, allowing accurate three-dimensional shape recognition.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a device used in a three-dimensional shape recognition method according to an embodiment of the present invention, FIG. 2 is a perspective view of a conventional three-dimensional shape recognition device, and FIGS. 3(a) (b) are each x
-y plane, zy plane explanatory diagram, Figure 3 (C) (d)
are the z-y plane and z of the conventional three-dimensional shape recognition method, respectively.
-A layout diagram showing the positional relationship on the x plane, Figure 4 is an explanatory diagram of the coordinates within the camera, Figure 5 (a) is an explanatory diagram of the generation of a virtual image due to specular reflection of slit light, and Figure 5 (b) is an illustration of the generation of a virtual image by specular reflection of slit light. The same figure (side view of al, Figure 6 is an explanatory diagram of the virtual image determination method using double cameras, Figure 7 is an explanatory diagram of double reflection of slit light, Figure 8
The figure is a side view of FIG. 7, and FIGS. 9(a) and 9(a) are explanatory views showing the coordinates of the virtual image and real image before and after rotation of the slit light generator, respectively. In the drawing, ■ is a slit light generator, 2 is a slit light, 3 is a slit light rotator, 4.10 is a camera, 5 is an image capture device, 6 is a coordinate calculator, 7 is a coordinate storage device, 8 is a virtual image discriminator 9 is an object to be measured, 11 is a real image, and 15 is a virtual image.

Claims (2)

[Claims] (1) A slit light is emitted from a slit light generator toward an object to be measured, and the reflected light of the slit light from the object to be measured is photographed by a camera, and the reflected light photographed by the camera is image-processed to create an image. In the method for determining the coordinates and recognizing the three-dimensional shape of the object to be measured based on each image coordinate, the coordinates of the position of the slit light, the angle formed by the slit light and the optical axis of the camera, and the specifications of the camera lens, By rotating the slit light generator, the irradiation angle of the slit light with respect to the object to be measured is changed, and the image coordinates of the reflected light taken by the camera are obtained before and after the rotation of the slit light generator, respectively, and the two are compared. , a three-dimensional shape recognition method characterized by extracting those whose coordinates of both images match or whose coordinates are small. (2) A slit light generator that emits slit light toward the measurement target, a camera that photographs the reflected light of the slit light from the measurement target, and image processing of each reflected light photographed by the camera. An image processing means that calculates each image coordinate and detects the shape of the object to be measured based on each image coordinate, the coordinate of the position of the slit light, the angle formed by the slit light and the optical axis of the camera, and the specifications of the camera lens. In the three-dimensional shape recognition device, the slit light generator is rotated, and image coordinates obtained by photographing with the camera and processing by the image processing means are stored before the rotation of the slit light generator. A coordinate storage device compares the image coordinates obtained by photographing with the camera and processing by the image processing means after the rotation of the slit light generator and the image coordinates stored in the coordinate storage device, and determines the coordinates of both images. A three-dimensional shape recognition device comprising: a coordinate discriminator that determines a match or a small difference as a real image.