JPH0452509A - Measuring method of three-dimensional shape - Google Patents

Abstract

PURPOSE:To enable discrimination of a color stripe corresponding to a position by a method wherein color stripe patterns in the number of N each of which is made up of stripes of (q) colors are projected to an object in N times sequentially, coded color stripe numbers separated in the number of qN are discriminated and, simultaneously, light-cut three-dimensional coordinates informations in the number of qN are acquired. CONSTITUTION:A color stripe image projected on an object 104 is picked up as one color image each one time synchronously with changeover of a pattern by a color camera 105 and stored as color images in the number of N on an image memory inside a three-dimensional coordinates computing device 106. Then, the stripe number of a color stripe is discriminated from these color images in the number of N and three-dimensional coordinates are calculated from the distortion of a slit image corresponding to each number.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for measuring a three-dimensional shape of a three-dimensional object by non-contact measurement of three-dimensional shape information.

Conventional Techniques Means for measuring three-dimensional shapes are broadly divided into contact and non-contact methods.Contact methods require a long time to measure, cannot accurately measure soft objects, and do not provide accurate surface data. There are disadvantages such as difficulty in collecting. For this reason, various non-contact measurement methods with few of these restrictions have been devised, but a light cutting method using optical slit light projection is widely used as a practically effective means.

Figure 4 shows the principle of the optical cutting method.
), a slit light projector 401 projects a thin linear slit light 402 onto the surface of a target object, and its image is captured by a television camera 403 or the like. At this time,
Three-dimensional coordinate information on the object surface can be obtained by extracting the distortion of the slit light caused by the unevenness of the object surface from the camera image. The three-dimensional positional coordinates of the point P on the object in FIG. 4(b) are determined from the base line length d connecting the slit light projector and the camera, the projection angle θ1 with respect to the base line, the camera horizontal angle θp, and the elevation angle θt of the camera image. It is determined by the principle of triangulation.

In such a light sectioning method, in order to know the three-dimensional position coordinates of every point on the surface of a target object, for example, one slit beam is sequentially scanned over the target object, and the coordinates are calculated at each scanning position. All you have to do is convert the throat image into coordinates in time series. However, scanning with such a slit light requires a scanning means and also takes time to collect data.

Therefore, a coded pattern projection method has been devised that can measure a three-dimensional shape at once in a stationary system without scanning with slit light.

In order to project multiple slit lights at once and obtain shape data of multiple points at the same time, it is necessary to characterize each slit light to identify them.
A method using color-encoded slit light as shown in (2) has been proposed.

(1) Yonezawa, Tamura: “Measurement of object shape using encoded grids”, Transactions of the Institute of Electronics and Communication Engineers, J-61D, 6°pp,
411-418 (197B) (2) Septum, wood:
Three-dimensional shape measurement of human face using color-coded slit light, Journal of the Institute of Electronics, Information and Communication Engineers, J-72D, 2. p
p, 2081-2069 Figure 6 shows an example of the arrangement of color coding strips IJ, ) in this method, where one slit light consists of one color and is characterized using q colors. .

From the way the books are lined up next to each other with colored slit lights like this,
The colors are arranged so that the slit numbers can be uniquely determined. That is, the arrangement of the colors of the k adjacent slit lights is encoded so that only -degrees appear in the total slit light, and as shown in the figure, #1, #
Each set of slit lights shown as 2, #3, etc. corresponds to the slit numbers assigned sequentially from the left and forms a uniquely identified color code. .

In this color coding slit method, by increasing the number of colors q or the code length k, the maximum flame of the code sequence, that is, the total number of slits that can be projected onto the object, can be increased, so the resolution of the measurement coordinates can be increased. It is unique in that it can be raised.

Problems to be Solved by the Invention However, when the number of colors is limited, if the code length k is increased in order to improve the resolution, the decoding procedure for associating many slit numbers becomes complicated and the device becomes difficult to solve. complicated,
There have been problems in that the identification processing speed is slow and erroneous identification is likely to occur.

The present invention eliminates the problem of the complexity of the decoding procedure in the conventional color-encoded slit light projection method, simplifies the device, and provides a three-dimensional method for projecting color patterns that allow easy identification of color codes. This paper attempts to provide a method for measuring shape.

Means for Solving the Problems The present invention provides a color pattern generator that generates N color stripe patterns each consisting of q color stripes, and a color pattern projector that projects the color stripe patterns onto a target object in time series. , comprising a color imaging device for capturing an image of the target object, and a memory for capturing a color image from the color imaging device at least N times and storing it as N digital color images, and color-identifying the image in the memory. By detecting the color stripe pattern, the three-dimensional coordinates of the surface of the target object are measured.

Effect of the present invention By the above method, N
This method sequentially projects the color stripe patterns onto the object N times, identifies the encoded color stripe numbers separated into qN pieces, and simultaneously acquires the qN pieces of light cutting three-dimensional coordinate information. Color stripes corresponding to positions can be identified without requiring a complicated decoding procedure for identification.

EXAMPLES Hereinafter, the present invention will be explained in detail based on examples. 1st
The figure shows an example of the basic configuration of an apparatus for realizing the three-dimensional shape measuring method of the present invention, in which 101 is a projection light source;
02 is a color slit pattern generator, 103 is a projection optical system, 104 is a target object, 106 is a color camera for imaging, and 106 is a three-dimensional coordinate calculation device. The color stripe pattern in the color slit pattern generator 102 is composed of N stripes, each consisting of color stripes of different density, and these N color patterns are sequentially switched in time series to apply the color stripes to the target object 104 N times. It functions like a projection. This color slit pattern generator 1
02 may be a device that mechanically changes the projection pattern, such as a slide projector, or may be a transmissive liquid crystal panel that electrically generates the projection pattern. The color line image projected onto the target object 104 is captured by the color camera 106 as one color image each time in synchronization with pattern switching, and N images are stored on the image memory inside the three-dimensional coordinate calculation device 108. From these N color images, the stripe numbers of the color stripes are identified according to the principle described below, and three-dimensional coordinates are calculated from the distortion of the slit image corresponding to each number.

FIG. 2 shows an example of the configuration of a set of N colored striped patterns in the color slit pattern generator 102. Each pattern consists of stripes of q colors, and the pattern number n: $1. #2゜#3. . . . It is assumed that stripes are formed in the order of #N from coarse to dense.

The coarsest stripe pattern 201 (#1) consists of color stripes that divide the effective screen width W into nine equal parts as shown in the figure, and the next coarsest stripe pattern 2o2 (#2) consists of the same pattern 201 (, $1
) is further divided into nine equal color stripes. Since the color stripes are sequentially divided into q parts along with the pattern number n, the total number of stripes in the #Nth pattern 203 is −qN...
1), and the stripe width W is w = W / K = W t('' -
--Given by (2).

Figure 2 shows q=3 for simplicity. The case where N=3 is illustrated, and the screen is finally divided into K-27 color stripes. In each color stripe pattern, the color arrangement of the stripes is
Q colors are arranged in a circular manner, and in the example shown in the figure,
Three colors, red R1 green G1 blue B, are arranged in the order of RGB.

If such a total number of N striped patterns can be identified as a stripe number relative to the screen position, three-dimensional coordinates can be obtained from a light sectioned image using K slits simultaneously, and the objective can be achieved. It can be seen that this stripe number can be easily identified by comparing the contents of FIG. That is, if the q colors are considered to be q-adic numbers, the closest stripe number divided into K pieces can be directly correlated as an N-digit q-adic number.

To explain specifically using FIG. 3, the three colors RGB are R==O, ()=1. Correspond to the ternary number n=2,
Let (xyz) represent a set of 3-digit color signals from cameras detected in the order of pattern projections, n=#1, #2, #3. However, X.

Y and Z represent R, G, or B. At this time, the ternary number (xyz) 3 represents =o ~ 26 in the stripe number, and the total is 2
Seven color stripes are identified separately.

In Figure 3, (RR4) is 20, and (BB
B) clearly corresponds to ni-26.

In order to detect the above q-adic N-digit color code, first the N color images stored in the arithmetic unit 106 in FIG.
Each sheet is identified into q colors and divided into color areas. Next, superpose the N images with n=#1 as the most significant digit and n=#N as the least significant digit, and convert each pixel position into a q-adic N-digit value (.

In order to facilitate color identification, the colors used for the color stripes should be the three primary colors of a color camera, G, B, their complementary colors C (cyan), M (magenta), Y (yellow), and these. It is recommended that you choose from a combination of colors.

Effects of the Invention As is clear from the above embodiments, if the color stripe pattern of the present invention is used, a complicated decoding procedure is not required to identify stripe numbers, and color stripes corresponding to positions can be identified. It is possible. Furthermore, the combination of the number of colors q and the number of projections N makes it easy to increase the number of distinguishable stripes, making it suitable for highly accurate three-dimensional coordinate measurement.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram showing the basic configuration of the device that implements the three-dimensional shape measuring method of the present invention, Fig. 2 is a diagram showing the structure of the color stripe pattern of the device, and Fig. 3 is the same. A diagram showing the contrast of color codes for identifying the line number of the device, Figure 4 is a principle diagram of three-dimensional shape measurement using the conventional light cutting method, and Figure 6 is a plan view of a conventional color-encoding slit. be. 101... Light source, 1o2... Color slit pattern generator, 103... Optical system, 104... Target object,
105... Color camera, 106... Three-dimensional coordinate calculation device. Name of agent: Patent attorney Shigetaka Awano and 1 other person Figure = 33 = 27 lines) 3 is a ternary digit diagram (b) Figure 5

Claims (2)

[Claims] (1) A color pattern generator that generates N color stripe patterns consisting of q color stripes, a color pattern projector that projects the color stripe patterns onto a target object in time series, and an image of the target object that is captured. comprising a color imaging device and a memory for capturing color images from the color imaging device at least N times and storing them as N digital color images;
A method for measuring a three-dimensional shape, characterized in that the three-dimensional coordinates of the surface of a target object are measured by color-identifying the image in the memory and detecting the color stripe pattern. (2) N colored striped patterns have stripe widths obtained by dividing a constant screen width into q to the nth power successively and equally (n=1, 2, 3,...N), and each colored striped pattern has a stripe width of q 2. The method for measuring a three-dimensional shape according to claim 1, wherein the colors are arranged in a circular manner.