From Images to Bodies: Modelling and Exploiting Spatial Occlusion and Motion Parallax

This paper describes the Region Occlusion Calculus (ROC-20), that can be used to model spatial occlusion and the effects of motion parallax of arbitrary shaped objects. ROC-20 assumes the region based ontology of RCC-8 and extends Galton’s Lines of Sight Calculus by allowing concave shaped objects into the modelled domain. This extension is used to describe the effects of mutually occluding bodies. The inclusion of van Benthem’s axiomatisation of comparative nearness facilitates reasoning about relative distances between occluding bodies. Further, an envisionment table is developed to model sequences of occlusion events enabling reasoning about objects and their images formed in a changing visual field.