The shape cognition and query supported by fourier transform

Abstract

As an important function of GIS, spatial query covers not only the extraction of geometric, topologic or semantic information but also the retrieval of spatial cognition related information. This study presents a shape based spatial query way that is formally described as: Select {Oi} From DataBase Where Oi.shape LIKE Template AtDegree. To extend the new operation LIKE in formal SQL language, the shape representation and measurement have to be built. This study aims at polygon object offering a Fourier transform based method to compute the degree of shape similarity. Through cognition experiment builds the membership function of fuzzy term LIKE. The query experiments show the shape based query retrieves the building result consistent with human cognition. © 2008 Springer-Verlag Berlin Heidelberg.