Management And Transformation Of Symbol Graphic Model In Digital Line Graphs & Map

The integration of maps and database not only refers to produce the two kinds of geographical feature expressions--DLG and maps,in one process at the same time,but also includes the integration of maps and database model data,that is,DLG and maps in a unified framework for expression,storage and management together.At present,share map data among the systems is difficult due to the differences in the structure of the geographic information system map models.Digital map needs an open,standard symbol graphical model to express and describe.It does not require the support of the symbol database,template or professional GIS platform software so that the user is easy to use map data and make a series of operations,is convenient for application and sharing of map data.This paper makes a research on the map symbol graphic model of digital line graphs and map(DLGM),use the model to express the map symbols,and use the symbolic graphic data as the component of the geographic entity,manage it with the DLG under the same framework.In this paper,the main work done as follows:1.A map symbol graphic model of digital line graphs and map is proposed,which is based on the unit symbol as the basic unit to constitute map symbols,and the map symbol is divided into 3 layers according to the hierarchical model: the unit symbol,the map group and the graphic elements.2.XML(eXtensible Markup Language)is used to describe the map symbol graph model,and the map data is described as an open,text format which follows the XML specification.It provides the graphic elements and a series of tags,key words to describe map symbol graphic model,map symbol graphs description grammar rules,map group and graphic elements description structure.3.Add a map symbol field in the database table based on the Geodatabase data model,which type is large binary object(Blob)and named SYMBOL,for storing and managing the map data described by XML.Therefore,digital line graphs and map can perform a variety of spatial analysis as DLG,it can also use the map data in SYMBOL to visualize the features and converts output to various map formats such as eps,svg.The map symbol graph model proposed in this paper can completely express all map symbols on the map;Specifies the public XML description rules of map data;Realizes the centralized management of map and DLG in the feature table of Geodatabase;Transforms map data to map publishing data correctly,and the conversion of the SVG map can be viewed in a network environment.In this paper,the research achievements were used in “Basic rules for vector data of 1:5 000 1:10 000 fundamental geographic information database of Shaanxi province”,the local standards in Shaanxi province.