Method and system for calibrating multiple cameras

Abstract

The invention relates to a method for calibrating cameras. In particular, the invention provides a method that estimates the position of interest points such as corners on images of array patterns, and uses such refined positions in an iterative calibration algorithm. The method can be extended to simultaneously process information from a large number of images from a plurality of cameras that are arranged in a fixed position on a mobile robot, wherein the images are representative of different camera poses. The optimization thereby provides a highly accurate estimate of camera calibration parameters.

We claim: 
     
         1 . A method of calibrating at least one camera, the method comprising steps of:
 (a) capturing at least one image of at least one array pattern, said image comprising a plurality of interest points, with at least one camera for at least one pose of each of the at least one camera;   (b) processing said at least one image to determine a provisional location of at least one interest point on the at least one image;   (c) refining the provisional position of said at least one interest point on the at least one image by:
 (i) selecting a partial area of the image that includes at least one interest point and at least a portion of at least two edges that meet at or near the interest point, 
 (ii) defining at least a first and second set of edge points representative of said at least two edges; 
 (iii) applying regression analysis to the first and second sets of edge points, respectively; 
 (iv) determining a refined position of the at least one interest point as the intersection of regression functions representative of the first and second sets of edge points; and 
   (d) optimizing camera calibration parameters based on the refined position of the at least one interest point on the at least one image.