Understanding Perceived Spatial Layout of Scenes: A Prerequisite for Prostheses for Blind Travelers

Abstract

When normally sighted people observe a natural scene, their perceptions include seeing the supporting ground surface and the arrangements of the objects on that surface, where each object is in relation to the others, to the ground surface, and to themselves. Seeing this arrangement is what is meant by the visually perceived layout of a scene. It is the major source of information to the visual system that provides control of locomotion through natural settings. Blind travelers have no comparable visually perceived layout, and must acquire information about the arrangements of the objects and the ground plane of the scene from vastly degraded visual sources, and more typically from non-visual sources, and from special devices designed to provide layout information. In the development of these prosthetic devices for blind travelers, designers have had to make ad hoc decisions both about how information of the physical layout of scenes is to be represented to the blind traveler and what information to represent, ad hoc because the designers do not know which sources of information are necessary, how that information is normally represented for sighted travelers, or whether blind travelers optimally use the same information.