Auto-Calibration of Pan-Tilt Cameras Including Radial Distortion and Zoom

Although there are intrinsic advantages of using pan-tilt-zoom cameras their application in automatic surveillance systems is still scarce. The difficulty of creating background models for moving cameras and the difficulty of keeping fitted pose and optical geometrical projection models are key reasons for the limited use of pan-tilt-zoom cameras. Geometric calibration is a useful tool to overcome these difficulties. In this work we propose a method for PTZ camera auto-calibration over the camera's zoom range. A new approach based on a division distortion model, which allows designing linear algorithms, is followed to solve the radial distortion when images are captured in different zooms. Results obtained over both synthetic and real data show that a full zoom range, complete field of view, pan-tilt-zoom camera calibration is possible.