Constraints on the Distortion of Area Objects in the Process of Map Objects Displacement

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. And three constraints including position, legible and characteristics are important for the maintenance of symbols equilibrium and spatial relationship, which are discussed in this paper. And the skeleton is introduced to represent area objects figure characteristic, with which area object can be separated to parts hierarchically according to importance in the construct. Then the finite element method is applied to the map objects' displacement and distortion. The strategy for the parameters of finite element method is discussed, a case study is followed at the last.