The Research And Application Of Map Symbol Interoperability Based On MSDT Engine

The map is a carrier of visualization for geographical information, and map symbol is main expression of map data. The conventional symbol library is binding on its platform, and the GIS can not share their symbol library, so it brings out a number of repetitive labors, prolongation of construction project. Therefore symbol sharing is an important part of geographical information sharing. Now three approaches to share symbol are format conversion, symbol corresponding table, and true type font library. However these methods all have a lot limitation. This paper bring forward a new method: symbol interoperability based on MSDT (Multi-Interface Symbol Display Technology) Engine, which is enlightened by ODBC technology. Symbol interoperability not only shares the symbol library data but also shares the functions about the symbols. Symbol interoperability is developed based on symbol data model, symbolization protocol, and symbol design environment. The symbol data model is the basis of interoperability. The symbolization protocol is the core of interoperability, which is the MSDT engine based on three-tiered architecture. The visual environment for symbol designing ensures expansibility of the interoperable symbol library. The implementation of symbol interoperability includes symbolization engine, symbol management middleware, and the symbol design middleware. This paper introduces the successful application of symbol interoperability in the Urban Pipe Network GIS in the end.