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.