Breadth-first search oriented symbolic picture representation for spatial match retrieval

Abstract To provide sufficient information for percepting symbolic objects among pictures from pictorial information systems, an efficient spatial data structure is needed to identify objects and to specify the spatial relationships among objects in a picture. In this paper, a new symbolic picture representation is proposed through the traversal of a quadtree corresponding to a given picture using breadth-first search and thus is called BFS string. An iconic indexing scheme for retrieving symbolic pictures based on the proposed BFS strings is presented and the algorithms introduced in the bin-tree oriented iconic indexing scheme by Chang and Lee (1998b) [Journal of Data and Knowledge Engineering 26 (2)]. is applied to the scheme for manipulating spatial relationships among objects. Compared with the bin-tree oriented scheme in storage complexity, experimental results show that the proposed BFS string requires less storage space when the picture has a great number of objects.