Visibility inference based on spatial knowledge representation from observer's perspective

In this article, we propose a picture‐based object‐oriented spatial knowledge representation, called PCOS‐string, for an environment seen from the observer's point of view. The PCOS‐string representation preserves the spatial relationships among objects and thus can facilitate spatial reasoning especially from the observer's perspective. We also present a visibility inference algorithm based on the PCOS‐string representation so that visibility of the objects in a given environment can be determined according to their spatial relationships. This visibility inference algorithm can handle both static and dynamic environments. Finally, we discuss the possibility of applying the PCOS‐string and the associated visibility inference method to the mobile robot's path planning problem and virtual reality applications. © 1997 John Wiley & Sons, Inc.