In this paper, we present a cooperative stereo system based on two pant-tilt-zoom (PTZ) cameras that can localize a moving target in a complex environment. Given an approximate target position that can be estimated by a fixed camera with a wide field of view, two PTZ cameras with a large baseline are pointed toward the target in order to estimate precisely its position. The overall method is divided in three parts: offline construction of a look-up-table (LUT) of rectification matrices, use of the LUT in real time for computing the rectification transformations for arbitrary camera positions, and finally 3D target localization. A chain of homographic transformations are used for finding the matching between different pairs of wide baseline stereo images. The proposed stereo localization system has two advantages: improved localization on a partially occluded target and monitoring a large environment using only two PTZ cameras without missing significant information. Finally, through experimental results, we show that the proposed system is able to make required localization of targets with good accuracy.
