METHOD AND DEVICE FOR CALIBRATING FOCUSING DISTANCE OF CAMERA

摘要

PURPOSE:To obtain reliable focusing distance and its reliability in calibration of focusing distance of a camera. CONSTITUTION:An image is input by a camera 12 using a rhombic lattice pattern 11 as a pattern for calibrating a camera. The edge of a lattice line is detected from the image by at edge detection means 21 and the lost point of the lattice line and the dispersion of the lost point are calculated based on the edge information by a lost point calculation means 22. The focusing distance is calculated from the lost point by a focusing distance calculation means 23 and dispersion of the focusing distance is obtained from the dispersion of the lost point by a dispersion calculation means 24. Reliability sections is calculated from the dispersion of the focusing distance by a reliability section calculation means 25. The rhombic lattice pattern 11, where two parallel lines cross at 2sin<-1>sq. rt. (3/10) degrees, is used and the focusing distance with the highest reliability can be obtained by setting the angle formed by the pattern and the image surface to cos<-1>sq. rt. (3/7) degrees.