The Definition And Design Of Map Data Model

Nowadays,the expression of Map is the real world with a certain scale to shrink and put the geographical elements on the map.Different types of map have different styles and specifications,and have different ways to describe maps.There is no unified model to express the "map" in the real world.Such as basic scale topographic maps,geological maps,hydrological maps,they have different data,supplemented with professional symbols and annotations,and combined with their own drawing specifications independently.The definition and design of map data model as the main research content,By the analysis of map and abstracting the common map elements.The map can be described by the parameters of the basic elements of a map,The qualitative analysis and quantitative expression of the map are realized.This paper focuses on the research of the map data model,and the results of the research are as follows:(1)In this paper,the map is divided into three basic elements: Frame,Mapbody,Decoration.It is proposed that the essence of the map is a page that shows the basic elements of the map,and defines the three main spatial reference to show the basic map elements.And the map is made up of several basic map elements in the corresponding coordinate system.(2)By the abstracting of map content,the mathematical expression of map element is given based on set theory,and the definition of map data model is determined: Map data model is to describe the structure and behavior of the three basic elements of map(Mapbody,Frame,Decoration)using the basic parameters that computer and people can understand and complete the expression of the map through on the aggregation and composition relationships of he three basic elements of map.(3)Parametric description of the map elements is to describe the map using parameters.So the description of the map is simplified as the description of the map parameters.The paper is proposed that and the process of mapping is the process of parameter index.(4)On the basis of the mathematical expression of map parameterization and the description of the aggregation and combination of map entities.this paper is to complete the design and expression of the map data model using Unified Modeling Language.