A method of division of urban fringe based on message entropy: ----A case study in Nanjing Cit

Urban fringe is a special area with interaction of urban and rural areas. So far how to identify urban fringe from urban area and rural areas is one of the major fields that urban geography concern. In this paper, remote sensing images of Nanjing district in 2003 is the calculating base. At the same time, the RS and GIS softwares are applied to program and recognize the image. A improved model of message entropy for land use was established based on the theory of information entropy and the feature of land use in city fringe. Through analyzing the distribution characteristics of entropy, the range of city fringe in Nanjing is confirmed with the entropy values of 60 and 68.Then this paper concludes a comparatively boundary between urban area and urban fringe. However, the paper also points out that the boundary of urban fringe is dynamic and in fact, subjective distinguishing with experience is needed in this process, this method has great feasibility in practice.