DYNAMIC FIXATION AND ACTIVE PERCEPTION

Fixation is the link between the physical environment and the visual o bserver, both of which can be dynamic. That is, dynamic fixation serve s the task of preserving a reference point in the world, despite relat ive motion. In this respect, fixation is dynamical in two senses: in r esponse to voluntary changes of fixation point or attentive cues-gaze shiftings, and in response to the desire to compensate for the retinal slip-gaze holding. The work presented here, addresses the vergence mo vement and preservation of binocular fixation during smooth pursuit. T his movement is a crucial component of fixation. The two vergence proc esses, disparity vergence and accommodative vergence, are described; a novel algorithm for robust disparity vergence and an active approach for blur detection and depth from defocus are presented. The main char acteristics of the disparity vergence technique are the simplicity of the algorithm, the influence of both left and right images in the cour se of fixation and the agreement with the fixation model of primates. The major characteristic of the suggested algorithm for blur detection is its active approach which makes it suitable for achieving qualitat ive and reasonable depth estimations without unrealistic assumptions a bout the structures in the images. The paper also covers the integrati on of the two processes disparity vergence and accommodation vergence which are in turn accomplished by an integration of the disparity and blur stimuli. This integration is accounted for in both static and dyn amic experiments.