Calibration of CCD-Cameras for Machine Vision and Robotics

Abstract

The basic mathematical formulation of a general solution to the extraction of three-dimensional information from images and camera calibration is presented. Standard photogrammetric algorithms for the least squares estimation of relevant parameters are outlined together with terms and principal aspects of calibration and quality assessment. A second generation prototype system for "Real-Time Photogrammetry" developed as part of the "Digital Photogrammetric Station" of the Institute of Geodesy and Photogrammetry of ETH-Zurich is described. Two calibration tests with three-dimensional testfields and independently determined reference coordinates for quality assessment are presented. In a laboratory calibration with off the shelf equipment an accuracy of 1120th and 1150th of the pixel spacing in row and column direction respectively has been achieved. Problems of the hardware used in the test are outlined. The calibration of a vision system of a ping-pong playing high-speed robot led to an improvement of the accuracy of object coordinates by a factor of over 8. The vision system is tracking table-tennis balls with a 50 Hz rate.