The Design And Realization For Dynamic Labeling In Electronic Map

Automatic map labeling is an important task of the automated cartography. It is a challenging task in cartography field, and plays an important role in GIS application and output.GIS is developed rapidly in recent twenty years, and it had been used in all fields of economy and society, this heips to extend the using and fortify the preduct of the electronic map .The electronic map is more dynamic, Real-time and alternating in expression, a new map will be shown while the display range or scale of the electronic map be changed by user, the contents are changed too,this required to seek proper palces for map labels by arithmetic in order to show a pretty map and avoid overlapping or absenting some information of label. Whith having refered to enough datas, the authe studies concerned method.1. The paper analyzes the characteristics of electronic map, combining with the Level of detail, discourses upon the conception of the electronic map dynamic labeling and analyzes & summarizes the characteristics of he electronic map dynamic labeling and the advantage / disadvantage of the realizing of dynamic labeling electronic map.2. According to analysis the question of electronic map dynamic labeling, the paper brings forward the descriptive model of dynamic labeling, analyzes the key problems of automatic labeling and studies the methods to resolve the problems. The paper analyzes the estimation rule of label quality and set up more maneuverable estimation model of label quality.3. The paper studies the data organization method and and realized the data structure which is suit to the dynamic labeling. With the object-oriented thought to abstract and deal with data, the paper puts forward that buffer should be set up in the data structure and its size is the important affection in the label quality estimation model. This method optimizes the label organization effectively.4. The paper analyzes and studies the arithmetic of existing on labeling, and brings forward the improved greedy search strategy which considers the class of elements weightiness and the elements of points, lines & polygons, and realizes the label dynamic configurations of points, lines & polygons elements.The greedy search strategy improved by the paper is applied in many GIS and obtains the good effect. The arithmetic can configure the label quickly and get high quality configurations in the test. The improved greedy search strategy is useful and effective in the label configurations.