Based On The Terrain Survey System The Design And Realization On The Electronic Cartography System

The electronic map is a new kind of map, which is a kind of screen map based on electronic technology. It appeared in 1980s. In the recent twenty years, it has been applied in many fields by the development of the computer science and the database technology. This paper mainly introduces some cartographic theories, techniques, methods and how to design and realize the electronic cartography system in the terrain survey system. The main contents are as follows:1, The intention and the importanceCompared with the traditional paper map, the electronic map has an advantage in many fields, such as self-adaptive, dynamic, information quantity, map drawing, map surveying, data share and so on. That is to say, the research and realization on the electronic cartography system is very important to us. The aim for the research on the electronic cartography system is to provide the electronic map drawing module for the terrain survey system.2, Some techniques of the electronic cartographyThe processing of the electronic cartography system contains data modeling, data collection, data processing, data management, symbolization and the color design.The data modeling is the prediction of the electronic cartography. It means that how we can organize and express the geographic space information in the bit world. A four-layer-tree structure that can express the geographic objects and the relations between them is presented. And some ordinary classification and coding methods are presented at the present time too.The data collection and the data processing are the foundation of the electronic cartography system. The data collection means the processing of digitizing all kinds of geographic information into the electronic map data formats. The data processing mainly contains the coordinates transform, the data precision processing, the topology processing and the data compressing. The map projection transform and the transform between the digitizing coordinates system, the map database coordinatessystem, the screen coordinates system are presented in this paper. And three geometric correcting methods are provided for correcting the error originated from the digitizing and the map paper's distortion too. The topology processing is the prediction of the data searching and analysis, and the vector map data compressing is good for economizing memory space and speeding up the data processing. The topology method and the data compressing method are discussed in this paper.The data management is an important step in the electronic cartography system. Firstly, the methods of data organizing, data storage, data searching and data editing are given. Secondly, a scheme of the map data management is built. The symbolization is the face of the electronic map. Some methods about how to symbolize the point object, the polyline object and the polygon object are presented in this paper.The color design is very important to the electronic map design. We discussed the character of color, the feeling of color, and some principles of the electronic map color design are given.3 , The functions to be realized in the electronic cartography systemThe main functions of the electronic cartography system consist of data editing, data drawing, map surveying and terrain analysis. The spatial object catch is the prediction of the data editing. A kind of attribute query and a kind of position query are brought forward, and a spatial object catch method is presented based on the attribute and position query. And then, we discuss how to zoom the electronic map, how to browse the electronic map, how to draw the electronic map as map layers or classes. In the electronic map survey, we mainly realize the coordinate survey, the area survey, the distance survey, the gradient survey and the orientation angle survey. At last, the gradient analysis, the altitude analysis, and the section analysis are reached. At the same time, we discuss how to display the electronic map, the three-dimension map and the multimedia together.4, the main research produc...