The displacement operator is an important and still a hot topic in map generalization. In the generalization product, symbols must be unambiguous and easily perceived and readily understood, which makes space competit...The displacement operator is an important and still a hot topic in map generalization. In the generalization product, symbols must be unambiguous and easily perceived and readily understood, which makes space competition among features an important obstacle in the process of map objects displacement. Space conflict between objects, through propagation process, may be spread and more objects may drift into it. In order to maintain symbols equilibrium and spatial relationship between objects, some unimportant symbols or parts of symbols should be distorted under constraints according to visual graphic resolution thresholds to figure out space competition among map features. Three constraints including position, legibility and characteristics are important for the maintenance of symbols equilibrium and spatial relationship, which are discussed in this paper. The skeleton is introduced to represent area objects figure characteristic, in which an area object can be separated to parts hierarchically according to their importance in the construction. Then, the finite element method is applied to the map objects’ displacement and distortion, in which a strategy for the parameters of finite element method is discussed.展开更多
This paper describes the real-time mapping displacement of buildings onto the polygon model of base terrain of geo-spatial information,The buildings are represented as height maps,lcading to low memory requirements an...This paper describes the real-time mapping displacement of buildings onto the polygon model of base terrain of geo-spatial information,The buildings are represented as height maps,lcading to low memory requirements and not involving changes of the original geometry（i.e.no vertices are created or displaced）.The displacement of buildings is mapped toward the protruding direction,The base of textrue which represents the ground in topography is correctly mapped onto base polygon without any distortion.This approach can exhibit the correct,occlusions between buildings and ground due to parallax and correct self-occlusion.展开更多
基金Supported by the National Science Foundation of China (No40401050)the Leading Academic Discipline Project of Shanghai Educational Committee(NoJ50104)the Science Foundation of Shanghai Education Department (07ZZ09)
文摘The displacement operator is an important and still a hot topic in map generalization. In the generalization product, symbols must be unambiguous and easily perceived and readily understood, which makes space competition among features an important obstacle in the process of map objects displacement. Space conflict between objects, through propagation process, may be spread and more objects may drift into it. In order to maintain symbols equilibrium and spatial relationship between objects, some unimportant symbols or parts of symbols should be distorted under constraints according to visual graphic resolution thresholds to figure out space competition among map features. Three constraints including position, legibility and characteristics are important for the maintenance of symbols equilibrium and spatial relationship, which are discussed in this paper. The skeleton is introduced to represent area objects figure characteristic, in which an area object can be separated to parts hierarchically according to their importance in the construction. Then, the finite element method is applied to the map objects’ displacement and distortion, in which a strategy for the parameters of finite element method is discussed.
文摘This paper describes the real-time mapping displacement of buildings onto the polygon model of base terrain of geo-spatial information,The buildings are represented as height maps,lcading to low memory requirements and not involving changes of the original geometry（i.e.no vertices are created or displaced）.The displacement of buildings is mapped toward the protruding direction,The base of textrue which represents the ground in topography is correctly mapped onto base polygon without any distortion.This approach can exhibit the correct,occlusions between buildings and ground due to parallax and correct self-occlusion.
