Bernardino and Santos-Victor 1999 : Presents an active binocular tracking system using log-polar images with contributions in both the perceptual and control aspects. The control part is based on the visual servoing framework, including kinematics and dynamics. We introduce a fixation constraint that simplifies the tracking problem by decoupling the visual kinematics and allowing us to express system dynamics in image coordinates. Simple dynamic controllers are designed for each degree of freedom directly from image features. In the perceptual part, we use a space variant sensor that emphasizes the center of the visual field (log-polar geometry). We present a disparity estimation algorithm for log-polar images and provide a theoretical analysis to illustrate the advantages of using space variant images. The overall system is implemented in the Medusa binocular head without any specific processing hardware. The use of log-polar images allows real-time performance (50 Hz). Tracking experiments are presented to illustrate system performance with different control strategies and objects of different shapes and motions.