JPS6189504A - Measuring device of body shape of 3-dimensional body - Google Patents

Abstract

PURPOSE:To attempt high-speed and high-accuracy of measurement, by photographing a plurality of light points projected onto a specimen as the 2-dimensional coordinates, searching for the light points 1-dimensionally along a locus of each light point on the 2-dimensional images. CONSTITUTION:Light points are formed by projecting many rays of light onto a specimen from a projector 9 well selected for the density of the light points and coordinates are determined by searching by an image data processing apparatus 11, the light points being photographed by a camera 10. Further, using X or Y of the coordinate system of the light points, calculating beforehand positions on the 2-dimensional coordinates as three coordinates suitea for determining 3-dimensional coordinates corresponding to the specimen and thus the specified value is determined immediately by, for instance, a table-lockup or utilizing an asymptotic equation. By these arrangements, an irregular shape of a 3-dimensional body can be measured accurately and rapidly.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a three-dimensional object shape measuring device, and in particular, to precisely measure the shape of irregularly shaped three-dimensional objects and perform data processing at high speed. It is related to the device.

(Prior Art) There are two conventional methods for precisely measuring the shape of an irregularly shaped three-dimensional object. One method is to repeat position measurement for each point many times with respect to arbitrary points on the object to be measured. A typical example of a measuring device using this method is shown in FIG. 4(a).

This figure is an example of measuring the shape of an irregularly shaped object whose δ11 constant object is nearly a hemisphere. The shape Ju11 determining device 1 includes a measurement table lb for positioning and placing the object to be measured A at the center of the main body 1a, a support 1c attached to both sides of the main body 1a, and a support 1c mounted in the M1 direction with respect to the Xx axis. R beam 1 attached to pillar IC so that it can rotate
It has d. The R beam 1d is driven by a motor 2 and has a probe carrier 3 that can slide the R beam 1d in the M2 direction. An omnidirectional touch probe 4 is attached to the probe carrier 3 so as to be movable in the M3 direction.
A stylus 4a is attached to its tip.

This type of shape measuring device 1 moves an omnidirectional touch probe 4 in Ml, M2, and M3 directions, and a stylus 4
The shape measuring device described above is a mechanical type that uses a touch sensor. Regarding measurement, a non-contact optical measurement method is also known in which an optical distance sensor is used instead of the touch sensor. FIG. 4(b) is a diagram showing the principle of position measurement using this method. The light beam emitted from the light emitting element 5a is reflected at an arbitrary point P of the measurement object B, and is reflected by the light receiving element 5b.
The distance between the optical distance sensor and an arbitrary point P is determined by calculating the angle θ formed by the reflected beam received by the optical distance sensor.

Next, another conventional method is a method using image processing applying image technology. An example of this is shown in FIG. 5(a). The projector 6 projects a grid pattern as shown in FIG. Photographed by aircraft 7. The photographed image of the lattice pattern is distorted in accordance with the measurement target C.
For example, the result is a deformed lattice pattern image as shown in FIG. The photographed deformed grid pattern image is subjected to two-dimensional data processing by the image data processing device 8, and the shape of the object C to be measured is calculated and output. That is, from the predetermined positions of the projector 6 and camera 7 and the degree of deformation from the original grid pattern, the angle θ at the intersection of the grids is calculated in the same manner as in FIG. 4(b). An object C is required. Depending on the shape of the object C to be measured and the required measurement accuracy, the measurement may be repeated several times. Therefore, compared to the method shown in FIG. 4, since the number of measurements is smaller, the measurement time is significantly shortened.

(Problems to be Solved by the Invention) However, the devices of the prior art have the following problems.

The mechanical shape measurement method described in FIG. 4 requires a mechanism for measuring from multiple directions.

Furthermore, in order to perform highly accurate measurements, it is necessary to increase the accuracy of this mechanism, which has the disadvantage that the device is expensive. Furthermore, since the position measurement for each point is repeated many times, there is a drawback that the measurement time becomes long.

The method using image processing described in FIG. 5 requires two-dimensional data processing in order to determine the shape of the object to be measured from the obtained image. Therefore, the data processing is complicated, and there is a drawback that an image data processing apparatus using a relatively large computer is required for this purpose.

The present invention solves the problems of the prior art and provides three-dimensional object shape measurement that can relatively easily measure the shape of an irregular three-dimensional object with 1rI density and high speed.

(Means for Solving the Problems) The present invention provides a projection machine that projects a plurality of light beams onto a three-dimensional object to be measured, and a plurality of light beams created on the three-dimensional object by the projector. A photographing device that photographs a point as a two-dimensional image, and a one-dimensional search for a light point along the locus of each light ray on the two-dimensional image output from the photographing device, and from the position of the light point, This is a three-dimensional object shape measuring device characterized by having an image data processing device that calculates the shape of a three-dimensional object.

Preferably, the image data processing device directly converts the coordinates indicating the position of the light spot on the two-dimensional image into a coordinate system representing the shape of a three-dimensional object given in advance.

Further, preferably, two of each light beam projected from the projector are
It is preferable to determine the directions of the light rays in advance so that the trajectories on the dimensional image do not approach each other.

(Function) According to the present invention, since the three-dimensional object shape measuring device is configured as described above, the technical means functions as follows. The image data processing device searches for light points one-dimensionally on a straight line, which is the locus of each light ray, on the two-dimensional image output from the camera, and determines the shape of the three-dimensional object from the position of the searched light point. Works like a calculation. Therefore, the above-mentioned problems can be solved.

(Embodiment) FIG. 1 is a diagram showing an embodiment of a three-dimensional object shape measuring device according to the present invention. Projector 9, Photography 4j1.10 and J
The fixed object is located at a predetermined position, as in the conventional example. The projector 9 does not project a grid pattern, but rather projects light points at predetermined intervals onto the object to be measured using a large number of light beams, as shown in the figure. This light spot may be a bright spot or a dark spot. In this embodiment, since the position of each light spot is determined, the density of the light spots is appropriately selected based on the object to be measured.

By photographing each light spot projected onto the object to be measured using a camera 10 such as a video camera, an image as shown in FIG. 2, for example, can be obtained. Next, the image of each photographed light spot is searched on the image by the image data processing device IO, and the coordinates of the light spot on the image are determined. The coordinate system of the image is
Any two-dimensional coordinates will do, but in the case of a video camera, XY orthogonal coordinates are convenient because of the nature of the video camera.

The present invention greatly simplifies image data processing by one-dimensionally searching for light spots on a two-dimensional image in the image data processing device 11.

Although each light ray from the projector 9 does not appear as an image, the locus (a) of the light ray becomes a straight line at a fixed position on the image, as shown in FIG. 2(b).

That is, since the projection a9, the camera 10, and the object to be measured are fixed at predetermined relative positions, the trajectory (a) of the light beam on the image will be the same on the image regardless of the shape of the object to be measured. This is a straight line at a fixed position, and the position on the image can be determined by calculation in advance. Therefore,
The light spot (b) follows the trajectory (a) according to the shape of the object to be measured.
Exists on a straight line. Therefore, there is no need to search for a light spot (b) on the two-dimensional image. That is, it is sufficient to search on the straight line of the trajectory (a) of the light ray.

If the image of the light point (b) is a bright point, the trajectory of this light ray (a)
A one-dimensional search is performed on the straight line until a bright point is found. In addition, if it is known in advance that the shape of the object to be measured falls within a certain range, such as for inspection purposes, there is no need to search over the entire length of the straight line on the image; All you have to do is search for the line segment. Therefore, the time required for searching is further reduced.

Further, due to various errors, the target light point (C) may deviate slightly from the straight line of the trajectory (A) of the light beam, as shown in FIG. 21(C). In such a case, when searching on a straight line, there is a risk of missing the light spot (c). Therefore, in order to prevent this, as shown in Figure 2(d), a circular light image (d) is created with a size such that the light spot (c) overlaps the trajectory of the light beam (a) even if there is an error. The optical image is adjusted in advance in the projector 9 so that Therefore,
When a bright point is found, the coordinates of the light point (C) can be obtained by searching the vicinity two-dimensionally, recognizing a circular light image, and determining the center of the circle.

As described above, if the position of the light spot deviates slightly from the straight line due to an error in the measurement system, the point on the straight line closest to the determined light spot (C) may be regarded as the light spot to be determined. Various methods can be considered for this method.

For example, there is a method in which a line is drawn perpendicularly from the light point (c) to the trajectory of the light ray (a), and the intersection point is used as the light point. In addition, focusing on the fact that the light image (d) is circular, we can determine the size and size of the circular light image (d) depending on the intensity of the light when searching along the trajectory of the light ray (a). There is a method of finding the midpoint from the intersection of the outer periphery and the trajectory (a) and using this midpoint as the desired light spot.

In this method, there is no need to find the center of the optical image (d), so only a completely one-dimensional search is required.

A large number of light rays are output from the projection v19. Therefore, as shown in FIG. 3(a), the trajectories (A) and (E) of the two light rays may be close to each other on the image taken by the photographing device IO. In such a case, the image of the light spot having the size is not only the light spot (d) that originally exists on the straight line of the trajectory (a), but also the light spot (2) that exists on the straight line of the trajectory (e). It is possible that the image of (b) is also recognized on the straight line of trajectory (a).

In such a case, the light point (d) existing on the straight line of the trajectory Vfi (a) and the light point (d) existing on the straight line of the trajectory (e)
).

This identification is impossible if the shape of the object to be measured is completely random. However, in general, the shape of the object to be measured is not significantly irregular. Therefore, it is possible to determine the three-dimensional coordinates of each light spot and determine that the light spot where the object to be measured has a more gentle shape is the correct light spot.

As described above, even if the above situation occurs, the present invention can measure the shape of a three-dimensional object without any problem. However, if such a situation occurs, data processing for identification will increase, so it is desirable to prevent such a situation from occurring.

The relative positions of the projector 9 and the camera 10 are fixed in advance. Therefore, since the coordinates of the trajectory of the light ray on the image are determined in advance, by selecting the direction of the light ray in advance,
It is possible to ensure that the trajectories of the light rays on the image are close to each other and that the image of a light spot is not focused on another light ray. However, 1
Such selection becomes impossible when the number of light rays on the image is extremely large. In such a case, the range of one measurement may be made smaller, and the number of light rays on one image may be reduced.

In addition, if the range of the object to be measured is limited and there is no need to search the entire length of the straight line on the image, but only the line segment, the above selection becomes much easier. . Even if proximity is unavoidable, Figure 3 (b
), the line segment of trajectory (a) and the line segment of trajectory (e) are only partially close to each other in part (g), so there are multiple images of light points on the line segment. Even if it were obtained, its identification would be much easier.

In this way, each light point on the image is found as one point on each straight line that is the locus of the light ray, and its coordinates are determined.

Once the coordinates of each light spot on the image are determined, the position of each light spot on the real image is determined. However, in practice, this must be expressed as a point on three-dimensional coordinates corresponding to the object to be measured. The calculations for this are generally complex. Therefore, data processing for this purpose also requires a long time. In the embodiment according to the present invention, data processing for this purpose is simplified and speeded up in the following manner.

By using either the Y or Y coordinate system of the light spot on the image, a convenient coordinate system [α
, β, γ]. That is, each party/point is on the beam from the projector 9,
Therefore, it lies on a fixed straight line on the image. If we use this relationship, we can obtain as or . Use one of these. Since the above formula is relatively simple, there is no problem in calculating the formula as is. However, it requires a large amount of memory in the image data processing device IO, but it is possible to store either one of the above formulas in the memory in the form of a table. If you have it built-in, you can immediately find a predetermined value using a table lookup.

Also, if you put the above equation in the form of an approximation equation such as a broken line approximation,
Although some time is required for the calculation, the total amount of r1 is significantly smaller than when the calculation is performed using the original calculation formula. Furthermore, memory capacity is significantly reduced compared to the table lookup method.

Therefore, any of the above methods may be used.

In the above embodiments, a light spot that produces a circular light image has been described, but it may be a light spot that produces a light image in the shape of a square (b) or a cross (+). Further, as the limit of the cross shape, a lattice pattern may be used as in the conventional method. However, crosses and the like require a lot of data processing to recognize the optical image. Furthermore, in the case of a lattice pattern, since a lattice other than the target light spot is recognized, extra data processing is required to determine the correct light spot. In this sense, a circular light image with size is most advantageous. However, there is no need to limit it to that. For example, if the optical image is used for other purposes and image processing is performed, the overall system may be advantageous even if the data processing for shape measurement itself increases.

(Effects of the Invention) As described above, according to the present invention, the shape of an irregular three-dimensional object can be measured precisely and at high speed.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an embodiment of a three-dimensional object shape measuring device according to the present invention, FIG. 2 is a diagram for explaining the embodiment of FIG. 1, and FIG. 3 is a diagram showing a case where the trajectories of light rays are close FIG. 4 is a diagram showing an example of a conventional mechanical shape measuring device, and FIG. 5 is a diagram showing an example of a conventional shape measuring device using image processing. 9...Projector, IO...Photographer, 11...Image data processing device.

Claims (3)

[Claims] (1) A projector that projects a plurality of light rays onto a three-dimensional object to be measured, and a camera that photographs a plurality of light spots created on the three-dimensional object by the projector as a two-dimensional image;
An image data processing device that one-dimensionally searches for a light spot along the locus of each light ray on a two-dimensional image output from the camera, and calculates the shape of the three-dimensional object from the position of the light spot. A three-dimensional object shape measuring device comprising: (2) Claims characterized in that the image data processing device directly converts coordinates indicating the position of a light spot on the two-dimensional image into a coordinate system representing the shape of a three-dimensional object given in advance. The three-dimensional object shape measuring device according to item 1. (3) The three-dimensional object according to claim 1, wherein the directions of the light rays are determined in advance so that the trajectories of the light rays projected from the projector on the two-dimensional image do not approach each other. Shape measuring device.