Design And Implementation Of GIS Symbol Library For Geological Mapping

GIS symbol library technology is an important means to solve the digital geological mapping.The GIS software has the existing symbol library system.It can complete the most of the geological symbols.However,some GIS symbol library system does not provide an interface to use.Some GIS symbol library system provide a call interface,but there are special requirements for the development environment.The parper studys the key technologies of GIS symbol library for geological mapping,which is to meet geological symbol visualization needs of "Geologist 3D Assistant" software developed by Chinese Academy of Surveying and Mapping.Through the analysis and summary of the existing GIS technology of symbol library and the geological standard in our country-Geological Symbols Used for Regional Geological Maps,this paper studies the key technologies that can meet China’s national for geological mapping.The research work done as follows:1)The paper studies the key technology of TrueType font primitive applied in symbol library.It is the foundation of a full geological vector symbol library. Firstly,it creates a geological point primitive library of TrueType format with FontCreator software;Then the geological TrueType point primitive library is applied in symbol library system. Finally, the windows platform provides the font access Interface to read the TrueType font point primitive.2)According to the geological characteristics of the symbol.object-oriented idea is used to design structure parameters of geological symbol library.The basic primitives include line primitive,filled polygons,polylines and TrueType fonts primitive.They combined into a point symbol,line symbols and symbols through a combination of planar and configuration properties.Three kinds of symbols form a complete storage symbol library structure.3)This paper studies three modules of geology symbol library development/They are editing module, storage module and rendering module.Editing module using MFC window and control technology designs geology symbol library editing interface and studies the editing method based on the classification of geological symbol.Storage module designs symbol organization structure and uses TXT files and TrueType file storage all symbols.It also can complete symbol functions of output,input and interpretation.Draw module is based on GDI and GDI+ technology.this paper designs drawing methods according to the characteristics of the data structure for point symbols, line symbols, area symbols.4)This paper using the C++programming language designs class and surface of GIS symbol library system for geological mapping.It achieve the symbol library prototype system with function of making geological point symbol、line symbol and area symbol.