Active Animate Stereo Vision

This paper describes recent research concerning the Active Stereo Probe (ASP)stereo vision system that combines animate oculo-motor reflexes with a novelactive illumination source. Two methods for accurate surface recovery from stereoat rates approaching real time are described. Results using texture projectioncombined with a fast sub-pixel matching algorithm are presented. Thedevelopment of a high accuracy, fast active ranging technique based upon temporalmodulation is also presented. A number of novel extensions are introduced toaddress this technique's traditional shortfalls and place it in a sound theoreticalframework. A calibration regime suitable for incorporating photogrammetrictechniques into the ASP active vision system during dynamic system operation isdescribed. 1. Introduction The Active Stereo Probe (ASP) project is concerned with both active andanthropomorphic approaches to vision. This paper sets out to describe some of theactive vision aspects of the project. Two differing definitions for active vision areevident in the computer vision literature. The utilisation of active illumination orradiant energy is the more established definition; while recent research using activelymobile passive sensors has also been termed active vision. The ASP system containscomponents of both types of active vision.One of the primary goals of ASP is to develop a stereo vision system applicablein domains such as biostereometrics, reverse engineering, virtual reality, telepresenceand symbolic coding for 3D video transmission purposes. We believe that real successin these application areas is critically dependent on the recovery of accurate three-dimensional surface models at rates approaching "real-time". It is also our belief thatsuch a system will require the flexibility provided by animate viewpoint control andvision based sensor control reflexes if its performance is not to be crippled byconstraints on scene content and the viewpoint of the cameras.Recent advances in Liquid Crystal light valve technology have made viable the useof non-coherent structured illumination sources that allow fast, accurate and flexiblestructured light approaches to the acquisition of 3D data from close rangephotogrammetry. In order to exploit this Liquid Crystal technology within the ASPproject, a state-of-the-art Active Illumination Projection System utilising a highcontrast, high resolution, Liquid Crystal Spatial Light Modulator has been developed.This also serves as a flexible test bed for determining optimal pattern generation andprojection characteristics.