A three-dimensional spatial model for the interpretation of image data

We present a means of generating and understanding relative spatial positions in a natural three-dimensional scene, in terms of six spatial prepositions, left, right, in-front, behind, above, and below, using real stereo images. Our model has two layers. First, a symbolic spatial description of the scene independent of reference frames is computed. Then, in the second layer, the meaning of each of the six prepositions is deened with respect to the current reference frame, based on the description from the rst layer. The meaning deenitions of the prepositions in the given model can be used in two ways. They allow the system to judge the degree of fullllment of each of the six prepositions between two 3-D objects according to a graduated scale; and given the 3-D object description of one object, the admissible 2-D image region of the other object can be inferred. keywords: 3-D spatial modeling, image interpretation, generation and understanding of qualitative knowledge, generation of spatial prepositions from images, spatial prepositions for object localization.