JPH03138507A - Method for measuring three-dimensional form - Google Patents

Abstract

PURPOSE:To process measurement at a high speed, to reduce an image memory and to enhance reliability by constituting the image memory of plural frames and also writing plural slit image data every frame. CONSTITUTION:An object 2 is irradiated with slit light which spreads in a horizontal direction from respective semiconductor lasers 4 and four light- sectioning beams r1-r4 are projected to the surface of the object 2 at the same time. Then, the light-sectioning beams r1-r4 are image-picked up by a CCD camera 5 arranged so that the optical axis of the camera may be inclined at a specified angle theta from the optical axis of slit light irradiation and stored in the image memory as multi-slit image data consisting of four slit images after being A/D converted. By driving a scanner, a laser array 3 scans in a direction shown by an arrow M every image pickup of light-sectioning beams r1-r4. Therefore, in the case of measuring the three-dimensional form all over the surface of the object 2, the light-sectioning beams r1-r4 at the time when the array 3 is positioned at the lowermost part in a section are image-picked up.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for measuring a three-dimensional shape, and more specifically, the present invention relates to a method for measuring a three-dimensional shape, and more specifically, the shape of a human body in medical care, the three-dimensional measurement of a human body in the apparel industry, and the three-dimensional shape of a mold. , relates to a three-dimensional shape measurement method applied when measuring the flatness, etc. of a steel plate.

[Prior art]

When measuring the three-dimensional shape of an object as described above, it is often necessary to measure the object without contacting the object. Typical measurement methods applied in such cases are the slit light projection method (light sectioning method) and the regular repeating pattern projection method (Moiré method). 12, p. 59, 1985) by Ime. In the three-dimensional shape measuring device 1a to which the above-mentioned slit light projection method is applied, as shown in FIG.
The light cutting line r is imaged by a CCD camera 5 disposed in a direction different from the irradiation direction of the slit light, and the slit image S corresponding to the light cutting line ``as displayed on a TV screen, for example, Based on the object 2a-3
The dimensional shape is now measured. 12 is a slit plate in which one slit hole is formed.

Such a three-dimensional shape measuring device 1a is capable of: (i) measuring the slit for one slit light within one frame time (usually 1/30 second), which is the measurement time for converting a slit scene into a slit image of one frame in the memory; It is possible to obtain image S,
The measurement of the profile shape of the object 2a at the optical cutting line r was highly reliable.

[Problem to be solved by the invention]

However, in the three-dimensional shape measuring device 1a according to the slit light projection method, when measuring the three-dimensional shape of the entire surface of the object 2a, the slit light is projected at equal pitches over the entire surface of the object 2a. must scan in the direction
For example, when processing 128 slit images, a little over 4 seconds of imaging time is required, and an image memory for 128 frames is also required.

On the other hand, in order to shorten the imaging time and reduce the required image memory, a three-dimensional shape measuring device 1 that applies a regularly repeated pattern projection method as shown in FIG. 4 is employed. The three-dimensional shape measuring device 1b includes a slit plate 12.in which a large number of slit holes are formed. A plurality of equal pinch slit lights (multi-slit lights) are projected toward the object 2I from a multi-slit light source comprising a light source 4a and a light source 4a, and as shown in FIG. It was possible to fit the multi-slit image m including all of S into one frame image, the imaging time was as short as 1/30 second, and the image memory was sufficient for one frame. However, when such a large number of slit images S are contained in one frame image, as shown in FIG.
Area C where slit images S intersect or are swapped
occurs, and the order of the slit image S, which identifies how many slit images S there are, becomes unknown, and it becomes extremely difficult to restore the three-dimensional shape of the object, making it difficult to obtain a highly reliable one. However, there is one problem.

Accordingly, an object of the present invention is to provide a method for measuring a three-dimensional shape that allows high-speed measurement processing, requires less image memory, and is highly reliable.

[Means to solve the problem]

In order to achieve the above object, the three-dimensional shape measurement method adopted by the present invention irradiates a measurement object with slit light from a slit light source, and uses a projected slit image of the measurement object on the irradiation optical axis. A series of operations are performed in which an image is captured using an imaging means provided outside, and the slit image data from the imaging means is stored in an image memory, and the slit light is scanned at a predetermined angle or interval at an equal pitch. In the three-dimensional shape measuring method, the three-dimensional shape of the object to be measured is measured at each scanning position of a light source, wherein the image memory is composed of a plurality of frames, and each frame has a plurality of slits. A feature of this device is that image data is written therein. Further, in a three-dimensional shape measurement method adopted to further reduce the required image memory, the slit light sources are arranged at equal intervals and are provided in multiple stages so as to emit a plurality of slit lights at the same time. The point is a structural feature.

[Effect]

In the three-dimensional shape measurement method according to the present invention, the image memory that stores the slit image data from the imaging means is composed of a plurality of frames, and a plurality of slit image data are written for each frame. The amount of slit image data that is displayed does not become more than necessary. Therefore, the order of each slit image does not become unclear, and the reliability of the measurement method is high.

Furthermore, by arranging slit light sources at equal intervals and arranging them in multiple stages so as to irradiate multiple slit lights at the same time, the number of slit image data written to the image memory at one time increases, thereby shortening the imaging time. At the same time, the image memory can be reduced.

[Examples] Hereinafter, examples embodying the present invention will be described with reference to the attached drawings to provide an understanding of the present invention. Here, FIG. 1 is a schematic configuration diagram showing a three-dimensional shape measuring device to which an embodiment of the method of the present invention is applied, and FIG. It is a schematic diagram which shows the aspect of a slit image.

The following examples are merely specific examples of the present invention, and are not intended to limit the technical scope of the present invention.

As shown in FIGS. 1 and 2, the three-dimensional shape measuring device 1 according to this embodiment method has four semiconductor lasers 4 equipped with cylindrical lenses (not shown) arranged in multiple stages at equal intervals in the downward direction. A laser array I 3 is disposed on a scanner 6 that mechanically scans a predetermined section P in the vertical direction, and irradiates the object 2 with slit light that spreads in the horizontal direction from each of the semiconductor lasers 4, Four optical cutting lines r1 to r4 are simultaneously projected onto the surface of the object 2. The optical cutting line rl"'-r4 is imaged by a CCD camera 5 arranged with a camera optical axis inclined at a predetermined angle θ from the slit irradiation optical axis,
Multi-slit image data consisting of four-tree slit images is stored in an image memory (not shown) after A/D conversion.

The image memory is functionally divided into seven frames from the first to the seventh frame. Further, the laser array 3b,
The scanner 6 is driven to scan in one direction (in the direction of arrow M) at a distance of 1/28 of the predetermined section 1), that is, at a pitch of P/28, each time the optical cutting line rl-r4 is imaged.

Therefore, when measuring the three-dimensional shape of the object 2 over its entire surface, first the optical cutting line r to r when the laser array 3 is located at the bottom of the section P is imaged. Then, slit image data s, I I・s2+ 1・corresponding to the optical cutting line rr2+ r3+ r4
5311. Conceptually, these images are stored simultaneously in the first frame of the image memory, as shown in FIG. Here, the suffixes of the codes attached to the slit image data will be explained. The leftmost subscript corresponds to the subscript of the optical cutting line rl-r4, the oldest subscript corresponds to the frame number of the image memory, and the middle subscript corresponds to the first frame to the seventh frame. is regarded as one round and corresponds to the number of rounds.

Then, after a predetermined time, for example, 1/20 second, the laser array 3 rises at a pitch of P/28, and the light cutting lines rl to r at that position are respectively slit image data SI.
+ 2 + 8219, 5312 + 3412 and stored in the second frame of the image memory. Thereafter, slit image data at different equal pitch positions are sequentially stored in different frames, and after 1/20 x 6 seconds, slit image data 5117, S2+7, 5317, 54
17 is stored in the seventh frame of the image memory. After another 1/20 second from this point, slit image data 5I21°S22 +, S corresponding to a position that is one step higher than the position of the laser array 3 at that point at a pitch of P/28 is generated.
321+S+21 is added to the first frame and stored as data for the second round of frame storage. Thereafter, similarly, slit image data corresponding to scan positions at equal pitches are sequentially added up to the seventh frame and stored as data for the second round of frame storage. In this way, finally the slit image data SI + 7 + 82
+7.83□7S447 is added to the seventh frame and stored.

In this way, four slit image data are added and stored in one frame four times each for the seven frames in the image memory, so 16 slit image data are stored in one frame. Slit image data, that is, slit image data corresponding to a total of 112 optical cutting lines in seven frames will be input.

The slit image data that can be stored in one frame of the image memory depends on the degree of change in the surface shape of the object 2. For example, if the object 2 is a human face and the predetermined angle θ between the optical axes of the semiconductor laser 4 and the CCD camera 5 is 60 degrees, the data can be restored even if the number of slit image data is set to about 20. In this embodiment, the number of slit image data stored in one frame is set to 16 so that no intersection or replacement occurs in subsequent slit images.

Hereinafter, the slit image data stored in all frames J of the image memory are set to a common coordinate system in three orthogonal directions, and a coordinate system rotated by a predetermined angle around the vertical axis of the common coordinate system. , is output to a general-purpose three-dimensional coordinate calculation means, and the three-dimensional shape of the object 2 is restored based on a well-known three-dimensional equation stored in the three-dimensional coordinate calculation means.

As described above, according to the method of this embodiment, when the number of slit lights scanning the entire surface of the object 2 is the same, compared to the conventional slit light projection method using one slit light, The measurement time was four times faster and the image memory capacity was reduced to 1/16 (7/112). Moreover, there is no ambiguity when determining the order of the slit image, and it is possible to realize a three-dimensional shape measuring device 1 that is extremely low cost, fast, and highly reliable.

Note that the laser array 3 is adjusted according to the degree of change in the surface shape of the object 2 and the optical axis opening angle θ between the semiconductor laser 4 and the CCD camera 5 within a range where the restored slit images do not intersect or replace each other. The number of semiconductor lasers 4 that are incorporated into the light source and serve as light sources may be increased or decreased. For example, the number of semiconductor lasers 4 may be one. Moreover, although the equal pitch scanning by the light source was performed at predetermined intervals with respect to the slit light, it may be performed at a predetermined angle with respect to the slit light.

Furthermore, when adding a large number of multi-slit image data to the same frame of the image memory as described above, the DC components of the individual multi-slit image data are added each time, and the base of the gray level increases. There is.

Therefore, it is predicted that the S/N ratio of the multi-slit image will decrease. In such a case, a method may be adopted in which the DC component of the multi-slit image data is subtracted each time to the original base level and then added.

〔Effect of the invention〕

According to the present invention, a measurement target is irradiated with slit light from a straight light source, and a projected slit image of the measurement target is captured using an imaging means disposed outside the irradiation optical axis. A series of operations including capturing an image and storing slit image data from the image capturing means in an image memory are executed at each scanning position of a light source that scans the slit light at a predetermined angle or interval at an equal pitch. A three-dimensional shape measuring method for measuring the three-dimensional shape of an object to be measured, characterized in that the image memory is composed of a plurality of frames, and a plurality of slit image data are written for each frame. A method for measuring three-dimensional shapes is provided, whereby the slit images do not intersect or interchange. Therefore, the order of each slit image does not become unclear, and the measurement method is highly reliable. Moreover, the required image memory can also be reduced. Furthermore, in the measurement method, the slit light sources are arranged at equal intervals,
By providing multiple stages so as to simultaneously irradiate a plurality of slit lights, the measurement time can be shortened and the required image memory can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing a three-dimensional shape measuring device to which an embodiment of the method of the present invention is applied, and FIG. 2 is a slit image stored for each frame in an image memory included in the three-dimensional shape measuring device. FIG. 3 is a state explanatory diagram showing an imaging state of a conventional three-dimensional shape measuring device using a slit light projection method, which is an example of the background of the present invention, and FIG. 4 is another example of the background. A state explanatory diagram showing the imaging state of a conventional three-dimensional shape measuring device using the regularly repeated pattern projection method, and FIG. 5 shows intersections of slit images measured by the three-dimensional shape measuring device according to FIG. It is a state explanatory diagram. [Explanation of symbols] 1.1a+tb...Three-dimensional shape measuring device 2.2&
+ 2b...Object 3...Laser array 4...Semiconductor laser 4a...Light source 5...CCI) Camera 6...Scanner

Claims (2)

[Claims] (1) A measurement object is irradiated with slit light from a slit light source, a projected slit image of the measurement object is imaged using an imaging means disposed outside the irradiation optical axis, and The slit image data is stored in an image memory, and a series of operations are executed at each scanning position of a light source that scans the slit light at a predetermined angle or interval at an equal pitch to determine the three-dimensional shape of the object to be measured. A method for measuring a three-dimensional shape, characterized in that the image memory is composed of a plurality of frames, and a plurality of slit image data are written for each frame. Method. (2) Measurement of a three-dimensional shape according to claim (1), characterized in that the slit light sources are arranged at equal intervals and are provided in multiple stages so as to simultaneously irradiate a plurality of slit lights. Method.