Method and apparatus for determining degrees of freedom of a camera
First Claim
1. A method for determining at least three degrees of freedom of a camera relative to a reference frame, said reference frame having a known spatial relationship to an optically modulated target, wherein said optically modulated target is asymmetric whereby ambiguity in the determination of said at least three degrees of freedom of said camera is substantially eliminated, wherein said optically modulated target further comprises at least one quadrilateral, and wherein said camera comprises an optical imaging means producing a predetermined geometric distortion, said method comprising:
- (a) sensing at least a portion of said optically modulated target using said camera to produce a video signal;
(b) processing said video signal using digital computing means, wherein said step of processing said video signal further comprises;
determining first coordinates of a first point from said video signal;
computing second coordinates of a second point, wherein said second coordinates are computed based upon said first coordinates and based upon said predetermined geometric distortion;
determining the vertices of said quadrilateral by computing the intersections of adjacent pairs of sides of said quadrilateral; and
using said vertices to determine said at least three degrees of freedom.
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Accused Products
Abstract
A method for determining up to six degrees of freedom of a camera relative to a reference frame comprises sensing an optically modulated target with the camera and processing the camera'"'"'s video output signal with a digital computer. The target may have a single pattern, multiple patterns, or patterns of varying size. Multiple targets may also be used. A very wide field of view camera may be used in conjunction with a method for removing geometric distortion from the camera'"'"'s view. Target patterns may be transmissive, reflective, or retroreflective, or may actively emit light. Asymmetric patterns are used to eliminate ambiguity in the recovery of the degrees of freedom.
163 Citations
27 Claims
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1. A method for determining at least three degrees of freedom of a camera relative to a reference frame, said reference frame having a known spatial relationship to an optically modulated target, wherein said optically modulated target is asymmetric whereby ambiguity in the determination of said at least three degrees of freedom of said camera is substantially eliminated, wherein said optically modulated target further comprises at least one quadrilateral, and wherein said camera comprises an optical imaging means producing a predetermined geometric distortion, said method comprising:
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(a) sensing at least a portion of said optically modulated target using said camera to produce a video signal; (b) processing said video signal using digital computing means, wherein said step of processing said video signal further comprises; determining first coordinates of a first point from said video signal; computing second coordinates of a second point, wherein said second coordinates are computed based upon said first coordinates and based upon said predetermined geometric distortion; determining the vertices of said quadrilateral by computing the intersections of adjacent pairs of sides of said quadrilateral; and using said vertices to determine said at least three degrees of freedom. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A system for determining at least three degrees of freedom of a camera relative to a reference frame, said system comprising:
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an optically modulated target having a known spatial relationship to said reference frame, said optically modulated target being asymmetric whereby ambiguity in the determination of said at least three degrees of freedom of said camera is substantially eliminated, and wherein said optically modulated target further comprises at least one quadrilateral; a camera having an optical image forming apparatus for forming an image on an image sensor, said optical image forming apparatus producing a predetermined geometric distortion of a formed image on said image sensor, said formed image on said image sensor including at least a portion of said optically modulated target; an optical image converting apparatus for converting said formed image on said image sensor to an electrical video signal; and a digital computer responsive to said electrical video signal, said digital computer determining first coordinates of a first point from said electrical video signal, and second coordinates of a second point, wherein said second coordinates are computed based upon said first coordinates and said predetermined geometric distortion, said digital computer being responsive to said electrical video signal to determine the vertices of said quadrilateral by computing the intersections of adjacent pairs of sides of said quadrilateral, and using said vertices to determine said at least three degrees of freedom. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
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27. In a system for determining at least three degrees of freedom of a camera relative to a reference frame, said system including an optically modulated target having a known spatial relationship to said reference frame, said optically modulated target being asymmetric whereby ambiguity in the determination of said at least three degrees of freedom of said camera is substantially eliminated, and wherein said optically modulated target further comprises at least one quadrilateral, an apparatus comprising:
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a camera having an optical image forming apparatus for forming an image on an image sensor, said optical image forming apparatus producing a predetermined geometric distortion of a formed image on said image sensor, said formed image on said image sensor including at least a portion of said optically modulated target; an optical image converting apparatus for converting said formed image on said image sensor to an electrical video signal; and a digital computer responsive to said electrical video signal, said digital computer determining first coordinates of a first point from said electrical video signal, and second coordinates of a second point, wherein said second coordinates are computed based upon said first coordinates and said predetermined geometric distortion, said digital computer being responsive to said electrical video signal to determine the vertices of said quadrilateral by computing the intersections of adjacent pairs of sides of said quadrilateral, and using said vertices to determine said at least three degrees of freedom.
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Specification