城市道路网的多尺度连续变换方法

本文提出了一种多比例尺道路网的连续变换方法,旨在解决在信息化大地图环境下城市道路网的多尺度连续表达需求。该方法首先对2种比例尺的道路网数据进行拓扑重建预处理,然后利用概率松弛匹配方法识别二者的要素对应关系。根据要素对应表,将2种比例尺道路要素分为1:1对应线状要素、1:0单独线状要素和M:N复杂线状要素3种情况：（1）对于1:1对应线状要素,本文采用简单线性Morphing变换方法;(2)对于1:0单独线状要素,首先对道路要素的直角特征进行识别,并定义直角及其前后一定范围内的线段为直角子线段,在此基础上,利用Douglas-Peucker算法将分割后的道路要素进一步分割,然后将直角子线段的起点和终点作为断点切割原道路要素,以顶点连续移位的方式实现连续综合变换;(3)对于M:N复杂线状要素,采用渲染颜色逐渐淡出的方法进行连续表达。最后,将3种情况的连续变换结果进行叠加组合。实验结果表明,本文方法能够获得良好的多尺度连续表达效果。

Continuous Multi-scale Transformation of Urban Road Networks

Presently, with the emergence of online mapping and Location Based Serveries (LBS), the continuous multi-scale representation of geo-spatial data has become a critical issue in the era of cartography and Geographic Information Science (GIS). This paper proposes a continuous transformation approach for the smooth representation of multi-scale road networks. Firstly, the topological relationships between the multi-scale road networks are reconstructed, and the feature correspondences are identified and classified into three categories (i.e., 1:1 matching features, 1:0 singleton features and M:N complex features) based on a probabilistic relaxation algorithm. For the 1:1 matching features, the corresponding points are identified based on the identical accumulated length ratio calculated from their starting vertex. The middle-scale representation of the 1:1 matching features is interpolated along the straight lines between the corresponding vertexes. For the 1:0 singleton features, considering that some road features are represented as a set of turns having approximately right angles, all the road vertexes containing an approximately right angle are detected and the edges connecting those vertexes are categorized into two characteristic sub-segments regarding as the left and right sides, which are then extended under the continuous direction. Then, the starting and ending nodes of the two characteristic sub-segment sets are selected to split the original road features into a set of divided line segments. Furthermore, the Douglas-Peucker algorithm is introduced to construct a hierarchical tree structure for each of the divided line segment, and all the divided line segments are hierarchically simplified by continuously moving the inner vertexes into the hierarchical tree structure. Moreover, the M:N complex features are visualized in gradually faded colors for a smooth representation. Finally, the continuous transformation results of different matching categories are integrated with respect to a given scale factor t. The experimental results have shown that the proposed approach can achieve a good performance for the continuous representation of the multi-scale urban road networks.