Patent ID: 6421629
Filing Date: 2002-07-16
Classification: G01B

Abstract:
A method for measuring a three-dimensional shape comprising the steps of:(a) projecting a light pattern having spatially striped luminance distribution on an object being measured, from light projection means, while phase-shifting the light pattern; (b) scanning said object illuminated with said light pattern while phase-shifting the light pattern from at least two different directions by cameras to output first and second image data; (c) deriving first and second initial phase images from a series of said first and second image data, respectively; (d) finding a set of corresponding three-dimensional coordinate positions from an initial phase of a target pixel, in said first initial phase image, based on a position of said light pattern projection and a first scanning position of said first image; (e) finding a set of pixel positions corresponding to said set of three-dimensional coordinate positions in said second initial phase image based on a position of the light pattern projection and a second scanning position of said second image, having reference to initial phases of the respective pixel positions, comparing the initial phases to an initial phase of the target pixel in said first initial phase image, and verifying whether or not a corresponding pixel position having a same initial phase can be uniquely determined; (f) finding a three-dimensional coordinate position based on the uniquely determined pixel position to determine an absolute value of an initial phase of a corresponding pixel in said first and second initial phase images; (g) repeating the steps (d) to (f) for entire pixels of said first initial phase image; (h) converting said first and second initial phase images into first and second absolute phase images in reference to the absolute value of an initial phase of said light pattern; and (i) finding a three-dimensional coordinate position of said object being measured in each pixel, based on the absolute phase in each pixel of said first and second absolute phase images, the projection position of said light pattern and the scanning positions of said first and second images.