Based On L System Of 3 D Map Symbol Study

Map symbol is the map graphic language, which works as a carrier and tool for expressing and transferring geographic information. The dimension of map symbol has been changed enormously during, from the traditional paper map to the computer digital map, then3D map,3D GIS and even VGE. At the same time, the way that observing the world from the perspective of humanity, has also been changed, from "from up to down" overlooking to "from the side see world" of scene mode, so the need of3D map symbol researches have become much more urgent. However, the current researches on3D map symbol are still in the bud, the existing3D symbol are mostly focused on3D model; At the same time, the current data structure of3D symbol is not perfect, it is not able to describe the complex shape of the geographical object. For this, we introduce the principle of L system method, which is3D symbol research based on L system,to study the complex object3D symbol of expression mechanism.The real world is complicated, and3D map symbol is a visualization of the real world tool. So, it is very important to research the3D map symbol of it based on L system.This article from the L system and the basic theory of map symbol, the L system of3D map symbol are analyzed, with reference to the composition theory of L system and visual variables for map symbol theory, the expansion and influence for that have been analyzed on L system for3D map symbol visual variables; Starting from L system and graphic composition rules, the data structure of3D map symbol based on L system that have been propose with the3D map symbol composition rules;A part of the filling algorithm has been analyzed. Main contents and results about this research are as follows:First of all, starting from three aspects with symbol,3D map symbol and L system, the classification system had been compared with the map semiotics and map symbol; At the same time, the definition and classification of3D map symbol had been analyzed, and the difference of3D map symbol and3D model had been analyzed; The theory research summary that had been proposed about L system concept and classification and feature deeply.Secondary, from cartographic semiology, according to the theory characteristics on L system and3D map symbol forms of expression, the description of visual variables for3D map symbol had been extended, based on visual variables theory system of classic map symbol by Bertin and the current3D map symbol.Thirdly, starting from graphic composition rules, introducing the principle composition on L system, according to the characteristics of3D map symbol and composition requirements for complex features, the data structure of3D map symbol based on L system that had been proposed.According to the L system string, the3D map symbol is organized by iterator and3D turtle parser based on L system. And, the filling algorithm had been analyzed, according to the composition feature of3D map symbol on L system.Finally, guiding by the visual variables for L system3D map symbol,3D map symbol rendering engine had been developed on the3D map symbol data structure for L system. The expression instances of L system3D map symbol had been realized. They had validated the applicability and feasibility for visual variables, data structure and partial filling algorithm of3D map symbol based on L system.