Optics: measuring and testing – Range or remote distance finding – With photodetection
Patent
1984-12-14
1987-05-12
Adams, Russell E.
Optics: measuring and testing
Range or remote distance finding
With photodetection
354408, G01C 300, G03B 300
Patent
active
046645128
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention is concerned with and intended for measuring the positions of points in three-dimensional space.
BACKGROUND ART
There are three prior techniques to which the invention is directed.
The first technique calculates the range from time lag in which light or acoustic wave is projected, reflected and received. Though it is easy to measure the range to one point by using this technique, it is difficult to measure ranges to many points in a short time.
The second technique picks up one point having characteristics in one image formed in one camera and another point having the same characteristics in another image formed in another camera, and calculates the ranged from these two points according to triangulation. Because it is difficult to determine the other point having the same characteristics, it is not easy to measure range by using this second technique.
The last technique projects a spot or a slit of light from one side, extracts the image of that spot or slit formed in a camera on another side, and calculates the range to the image according to triangulation while the spot or slit is moved. There remain such problems as the existence of points which cannot be reached by the spot or slit, as it is occasionally difficult to extract the image of the spot or slit because of round brightness, and as it is difficult to measure range with high accuracy because the spot or the slit has some area.
These three prior techniques are detailed in "Visual Sensor and Environmental Recognition" printed in monthly magazine "Sensor Technology" published in January of 1982 in Japan.
DISCLOSURE OF THE INVENTION
An object of the invention is to provide a range finder which can measure the positions in three-dimensional space of individual minute parts constituting an object.
The invention utilizes optical information outputted from each pixel of a camera in which the minute parts of the object form its image. If the range to these minute parts can be measured, the positions in three-dimensional space of these minute parts can be calculated because the direction to the minute parts can be determined by the position of the pixels in camera. For convenience in explanation, the minute parts of the object are referred to as object points, and the color information outputted from each pixel is referred to as a pixel datum.
In order to measure the range to the object point, the invention utilizes an object point whose optical information, or pixel datum outputted from the pixel in which said object point forms its image, is different from that of another object point accessing to the first said object point. The relationship between such a datum outputted or calculated from one pixel as said pixel, said pixel datum, and said object point is referred to as "corresponding to".
First, the object point forms its images in two pixels (one located in one camera and the other in the other camera) whose lens axes are not the same, the pixel data corresponding to which represent the same, and each is different from the pixels accessing to said two pixels. Then the range can be calculated from three factors such as the interval between the two lens axes, the angle of the two axes of the lens, and the two positions of said pixels in their respetive cameras. The range finder of the invention can measure ranges to various object points by measuring some variable factors of the three while the other factors are fixed.
However, it is not efficient on the point of time to compare every two pixel data for every value of the variable factors. If there are some pixels the pixel data corresponding to which represent the same and are both different from other pixel data corresponding to other pixels accessing to said some pixels, it will be impossible to determine one range because a number of ranges are measured. Then, if the range finder has means for extracting only pixel data outputted from pixels in which the object points inside respective depths of focus of the lenses, which are moved, form their images, it wil
REFERENCES:
patent: 3274914 (1966-09-01), Biedermann et al.
patent: 3945023 (1976-03-01), Stauffer
patent: 3958117 (1976-05-01), Stauffer
patent: 4078171 (1978-03-01), Stauffer
patent: 4561747 (1985-12-01), Ohno et al.
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