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One of the ways that we perceive shape is through seeing motion. Visual motion may be actively generated (for example, in locomotion), or passively observed. In the study of the perception of three-dimensional structure from motion, the non-moving, passive observer in an environment of moving rigid objects has been used as a substitute for an active(More)
Stabilization of gaze is a major functional prerequisite for robots exploring the environment. The main reason for a steady-image" requirement, is to prevent the robot's own motion to compromise its visual functions". In this paper we present an artiicial system, the LIRA robot head, capable of controlling its camerasseyes to stabilize gaze. The system(More)
This work describes a technique for measuring human head movements in 3D space. Rotations and translations of the head are tracked using a light helmet fastened to a multi-joint mechanical structure. This apparatus has been designed to be used in a series of psycho-physiological experiments in the field of active vision, where position and orientation of(More)
This work addresses the problem of learning stabilization reflexes in robots with moving eyes. Most essential in achieving efficient visual stabilization is the exploitation/integration of different motion related sensory information. In our robot, self-motion is measured inertially with an artificial vestibular system (gyroscopes) and visually by(More)
Robot systems that rely on vision as their main sensory capability need to be able to cope with changes in the visual environment and to manage a wide eld of view. Moreover, in order not to loose real-time response capabilities, selective visual sensing is indeed highly desirable. The \built-in" selection in space and time provided by space variant sensors(More)
Stabilization of gaze is a fundamental requirement of an active visual system for at least two reasons: i to increase the robustness of dynamic visual measures during observer's motion; ii to provide a reference with respect to the environment Ballard and Brown, 1992. The aim of this paper is to address the former issue by i n vestigating the role of(More)
We investigated the ability of monocular human observer to scale absolute distance during sagittal head motion in the presence of pure optic flow information. Subjects were presented at eye-level computer-generated spheres (covered with randomly distributed dots) placed at several distances. We compared the condition of self-motion (SM) versus object-motion(More)
We investigated the role of extraretinal information in the perception of absolute distance. In a computer-simulated environment, monocular observers judged the distance of objects positioned at different locations in depth while performing frontoparallel movements of the head. The objects were spheres covered with random dots subtending three different(More)