Study On Several Issues Of 3D Map Design Based On Spatial Cognition

Spatial cognition is one of the major topics at the forefront of cognitive science. Spatial cognition theory has the significant theoretical guidance value for the development of Cartography and GIS in current. Map spatial cognition is the core of the modern cartography theory. At present, spatial cognition research is still very limited (Gao Jun,2008), and the research objects of majority literatures about it are 2D map. There have an urgent need of the guidance of spatial cognition theory under 3D environment with the rapid development of 3D map. As a consequence, this paper selects 3D map as the research object, and the spatial cognition rules of it are investigated in here. Based on this, several issues of 3D map design are discussed. The main research works of this paper are as follows:(1) This paper reviews and summarizes the research course of spatial cognition at home and abroad. The author induce and analyze the research focus and the research progress on spatial cognition at home and abroad within each period of time respectively, emphasize the importance and necessity of studying on spatial cognition. Compare with the foreign research situation about spatial cognition, it starts relatively late in our country, but it develops swiftly and follows the steps of the international spatial cognition research closely. Now, it has made some theoretical achievements, which are got together and classified in this paper. As a frontier research topic, the correlation theories of spatial cognition are still not perfect and the related systems are also inadequate, they remain to be further investigated by the experts and scholars of various disciplines especially in the field of geography and psychology.(2) This paper summarizes and analyzes the current research of 3D map at home and abroad. The author elaborates and classifies the research contents of 3D map, introduces the current application situation of 3D map briefly. This paper points out that it has some problems in 3D map, such as the expression means is unitary and the map function is not perfect and so on. They remain to be further investigated by the cartographer. There shows that the topics of this paper are meaningful.(3) The correlation theories of the map spatial cognition are described in this paper. The author introduces the cognitive science and its research direction and development trend briefly, elaborates the correlation theories of the spatial cognition from the following aspects:cognition, spatial cognition and geographic spatial cognition, and explains their concept and the research contents separately. The research purposes and the research contents of the map spatial cognition theory and the basic processes of the map spatial cognition are mainly studied in this paper.(4) Several spatial cognition rules of 3D map are studied in this paper. The author explains why 3D map is considered as a kind of map from the perspective of the definition of the traditional map, introduces 3D map in detail from four aspects:the concept, the expression contents, the designing and producing process, the expression forms in existence. Based on combing network questionnaire survey with experiment on the spot, several spatial cognition rules when the user uses 3D map are investigated by analyzing five investigation and experimental results, several rules which the 3D map layout influence the spatial cognition are investigated by the investigations and experiments of six aspects. The characteristics of mental map which is produced based on 3d map are mainly studied by two experiments and a spatial cognition model is represented in this paper.(5) The models of light and shadow are established in this paper. The author illustrates the research significance of the light model and the shadow model in 3D map, analyzes their spatial cognition factors. Eight spatial cognition functions of the light and shadow in 3D map are presented. On the basis of studying the visual variables of light and shadow in detail, the author puts forward the principles of building the models of light and shadow. The light sources in 3D map are divided into four types:the dawn-dusk scattered light, the sunrise and sunset light, the normal oblique light and the top light at noon. Based on analyzing their characteristics, the change rules of the color of light and shadow along with the solar altitude are discussed deeply. And the models of light and shadow in 3D map are constructed by six formulas.(6) In this paper, the automatic modeling of 3D cliff symbol is explored. The author explains the theoretical basis of 3D symbol design from the following aspects: the classification and the characteristics of 3D map symbol, the differences between 3D map symbol and 2D map symbol, and the design rules of 3D map symbol. In view of some relief symbols are difficult to build the modeling in 3D topographic map, this paper takes cliff symbol as the example, proposes a method to exact the edge lines of cliff based on TIN, sets up an illumination model of cliff symbol according to the visual sensation rules under the different illumination conditions and researches the mathematical expression of it, and introduces the automatic modeling flows of cliff symbol. The study will be helpful to build the modeling of other similar relief symbols automatically.(7) The principles of the placement of 3D map label and its implementation strategies are discussed preliminarily in this paper. The author explains the 3D map label and its classification, summarizes some common expression forms of 3D map label. Based on studying the cognition rules of 3D map label, the author mainly analyzes the visual variables and the influencing factors of 3D label. The spatial cognition environment of the label placement of 3D map is parsed. The Gestalt principles which the placement of the 3D map label observes are studied. The automatic placement principles and its implementation strategies of the label of the various features are discussed comprehensively. These features constitute the 3D map, such as the point features, the linear features, the area features and the stereoscopic features. An automatic placement method of the label of the 3D area features based on the constraint Delaunay triangulated network is presented. The related module of the automatic placement of 3D label is developed based on ArcEngine and VB.net. It is applied successfully in the automatic drawing system of 3D map.