Sphereo: Determining Depth using Two Specular Spheres and a Single Camera

Abstract

This paper proposes a method for determining the depth of points in a three-dimenswnal scene. The concept is to use two spheres with highly specular surfaces to obtain two dilferent perspectives of the scene. Both spheres are viewed by a single stationary camera, and each sphere reflects the world around it into the camera. Correspondence between points on the two spheres is established by matching features such as edges and image intensities, as in traditional stereopsis. Depth is recovered from each pair of corresponding points by triangulation. The use of a single fixed camera avoids the undesirable complexities that characterize the stereo calibration procedure. The measurable range of the system is greatly enhanced by the use of specular spheres and is not limited by the field of view of the camera. Experiments were conducted to determine the accuracy in depth measurement and the feasibility of practical implementation. The technique presented in this paper has been named "SPHEREO" as it was two SPHeres, rather than two cameras, to emulate stEREOpsis.