基于约束条件的地图目标移位

地图目标移位是地图综合和空间信息可视化研究中的一个重要问题,其难点是如何在移位过程中满足一定的约束条件以保持目标之间的空间关系。本文以城市道路扩张为例,借助带约束性Delaunay三角网,结合有限元和空间推理方法,重点探讨顾及空间关系的基于约束条件的地图目标移位问题,并给出满足一定约束条件下的节点移位算法和计算实例。

Map Objects Displacement under Constraints

Map objects displacement is an important operator in the map generalization and visualization of spatial information,and the key of displacement operator is how to satisfy constraints necessary for the maintenance of spatial relationship between map objects.In this paper a method of map object displacement under constraints,based on the finite element method and spatial reasoning,is examined.At first,some basic concepts of finite element method are introduced, and three common constraints of position,characteristics and legible in the map objects displacement are discussed,and then the strategies of classification and weighting rules for the map objects are examined,and then a method for the constraints satisfaction based on the finite element method and spatial reasoning is presented,which is followed by the discussion of a progressive node displacement algorithm,and at last,a case study of road widening with this method is presented.And the result shows that the road is parallel strictly and spatial topological relationship between roads and districts are maintained after the widening process,but spatial confliction still happened to district objects in the dense objects areas.And at the same time,the method shows some characteristics including that the forces produced by the road node displacement and push on the partition boundaries of other objects can be assembled and evaluated simultaneously,and through the spatial reasoning process,the force propagation in the displacement process can be controlled by setting boundary conditions and then map objects displacement outer this boundary are avoided.