Research On Automated Symbolization Of River Networks For Digital Mapping

Computer technology, along with automation technology, has created new ways for the development of cartography. Automatic digital mapping has developed from the original theoretical probing, equipment development to the gradually mature software design and its further extensive applications. Moreover, studies on the structure of cartographic data, its organization and management, have entered a new stage characterized by full digitalization and full automation.As symbol is considered as the language of map, map would mean nothing without it. Undoubtedly automatic map symbolization is an important part of automatic map compilation and even automatic digital mapping. River network is one of the features that map symbol should represent, and also is one of the important contents in the digital map which makes its skeleton-control role in the geographical environment. Symbolizing river networks has always been a repeated working process that requires both a lot of time and energy, because the structure of river networks as a whole possesses shape complexity, asymmetry and branching phenomenon, and also because river networks symbolization is lack of specific rules and theoretical guidance. This paper first analyzes river networks entities and their inherent law as mapping objects, then describes their structures on the basis of the graph theory, further after preprocessing our original data, organizing them and later constructing our cartographic data model, transforms our original data to a cartographic mathematical model, builds the structure of river networks, extracts rules for river networks symbolization, finally symbolizes river networks automatically, and then outputs river networks symbols which coordinates to the corresponding cartographic symbols specification. In the last part we design a symbolization module for a digital mapping system to prove the ideas about river networks symbolization expressed in this paper.