Active Vergence Behavior

This paper describes a real-time vergence control mechanism developed for the stereo head MEDUSA 13], in the context of behavior based active control 3]. Real-time control architectures for active vision impose strong constraints on the computational complexity of image processing algorithms. In many applications, the image size is often drastically reduced in order to achieve fast and reactive routines, at the cost of precision in the output of the algorithms. Non-uniform sampling of the images, through the log-polar mapping, is an eecient way of reducing the amount of data to process 8, 17], while maintaining a good resolution in the center of the eld of view. By using active vision devices, such as stereo heads, we are able to inspect a wide eld of view with high resolution. Besides the image size reduction feature, the correlation index of log-polar images, as a function of the vergence angle, has major advantages over cartesian images, in the detection of correct vergence conngurations 9]. Moreover, in this paper we show that the correlation index can be used for robust vergence control, with very low resolution log-polar images, leading to a very fast visuo-motor process. There is no explicit disparity estimation and the control law is a function of direct image measurements. A performance analysis of the of this method for several log-polar sensors is done, establishing criteria to choose adequate layouts. A real time implementation is described and extensive experiments have been performed. Abstract This paper describes a real-time vergence control mechanism developed for the stereo head MEDUSA 13], in the context of behavior based active control 3]. Real-time control architectures for active vision impose strong constraints on the computational complexity of image processing algorithms. In many applications, the image size is often drastically reduced in order to achieve fast and reactive routines, at the cost of precision in the output of the algorithms. Non-uniform sampling of the images, through the log-polar mapping, is an eecient way of reducing the amount of data to process 8, 17], while maintaining a good resolution in the center of the eld of view. By using active vision devices, such as stereo heads, we are able to inspect a wide eld of view with high resolution. Besides the image size reduction feature, the correlation index of log-polar images, as a function of the vergence angle, has major advantages over cartesian images, in the detection of correct vergence …