Research On Key Technologies Of Map Symbol Sharing

The sharing and interoperation of spatial information is the tendency and hotspot ofdevelopment in geographical information field. However, the sharing theory and technology ofmap symbol compares unfavourably with the sharing of spatial information, though it is animportant part of the latter. On the one hand, the formulation of relative standards of map symbolsharing deviates from the application. On the other hand, the present map symbol sharingmethods have serious limitations on the effiction, range and capability of the sharing. It is hardfor multi-source and heterogeneous map symbol to integrate and interoperate openly on theinternet. Wasting resource is always happen because of the repeated exploitation of map symbol.Consequently, this dissertation works with the sharing framework and key technologies of mapsymbol. On the basis of open map symbol data model and united encoding, the framework ofsharing map symbol based on SOA is established to provide a new way for independent mapsymbol to realize integration and interoperation on the web environment. The main work andinnovation of this dissertation are as follows.(1) The sharing of geographical information is gradually progressing in its theory andtechnologies. On this background, the status quo of map symbol’s sharing implementation,correlative methods is expatiated. Then the existing issues and weak point is summarized andanalysed. After comparing their merits and demerits, as well as application limitations, with theseveral sharing methods of map symbol, the target and meaning of building map symbol sharingframework is proposed in the dissertation in order to realize the integration and interoperation ofdisperse, multi-source and heterogeneous map symbol.(2) The transit model for sharing map symbol information is put forward in the dissertation.Then the demand and purport of open map symbol data model is defined. After analyzing themap symbol edit module of sevarsal GIS software, the familiar data model and protractedarithmetic of point, line and area symbol is epurated. Then the united abstract interface model ofmap symbolization and map symbol is designed and the open point, line, area and text symboldata model is built. Finally, in order to test that the model can support the renewed organizationof different map symbols, the compatibility of the open map symbol data model is analyzed anddesigned.(3) Styled layer description and symbol encoding specification formulated by OGC,graphical description language and XML language are the main map symbol coding language inpresent. After taking a contrast with these main languages, the map symbol coding principles arefounded and the coding content together with its hiberarchy are analyzed. On the basis of openmap symbol data model, the map symbol coding specification based XML Schema is designed. (4) With the ground of Web services concept and structure, the deifinition and framework ofmap symbol service is brought up. Consulted with the relative geographical information servicesimplementation promulgated by OGC organization, the implementation of map symbol service isstipulated. And the request and response process of three web method interface—GetCapabilites,DescribeSymbolType, GetSymbol—are designed in detail.(5) The map symbol sharing framework based on SOA method is built. The frameworkcontains three symbol role members and several sustainable elements. And it works with the helpof three members’ interoperations. The map symbol classification considering the application isproposed. Then in order to evaluate the quality of map symbol, the AHP(Analytic HierarchyProcess) method is used to get the weight of quality factor and the linear weighted function isutlilized to compute the quality value. Last, the map symbol information metadata and categorydatabase, as well as the function modules of registry center—registry, discovery and databasemanagement—are designed and research.(6) The key technologies for the extended application of sharing framework are researched.First, to extend the registry center role member, the map style description schema, web registryand discovery methods are raised. Second, to extend the symbol provider role member, astructure of online symbol editor is built, the map symbol data model based on Silverlight isdefined and the function modules of online symbol editor is designed. Third, to extend thesymbol requester role member, the online cartographical platform is founded and the keyfunctions of the platform are researched and designed.(7) Aiming at testing the map symbol sharing framework and its key technologies, acomprehensive experiment of map symbol framework is taken. The structure of experiment isbuilt and the logical function mechanisms are summarized. Then there are six experiments arebuilt—the integration of multi-source, heterogeneous map symbol, the coding and web serviceencapsulation of map symbol, maps symbol registry center website, map symbol online editor,online cartographical platform and GIS drawing interoperation based on symbol sharing. Theseexperiments cover many aspects of symbol sharing technologies such as designing map symboldata model, symbol coding, Web services encapsulation, symbol registry, search and discovery,online edited and abroad applications.