利用“计算区”进行建筑物短边结构识别和渐进式化简

Recognition and Progressive Simplification of Short-Edge Structure of Buildings Using Calculation Regions

  • 摘要: 已有的建筑物化简方法大多侧重于化简原则中的某一方面,且对制图专家已有的化简共识考虑不足。通过模仿制图专家建筑物化简的思维过程和操作流程,提出一种利用“计算区”(与某组小于阈值的边化简有关的节点序列称为该组边的计算区)进行建筑物短边结构识别与渐进式化简的方法。首先对建筑物轮廓进行预处理和垂直增强;然后对其分组,并利用“计算区”对小于阈值的边进行结构识别、分析,确定最优化简方案;最后通过整体调整,在形状保持的前提下减小面积差。以众源开放街道地图(OpenStreetMap,OSM)建筑物数据为例,将所提方法与ArcGIS建筑物化简工具化简的结果进行对比分析,实验结果表明,所提方法有效减少了图形节点数,增强了平行、直角等形状特征,并减小了化简前后面积差,较好兼顾并平衡了建筑物化简原则的几个方面,为建筑物化简提供了新思路。

     

    Abstract:
      Objectives  Most of the existing building simplification methods focus on one or two aspects of the three principles: Area preservation, shape characteristics enhancement and drawing rectangles if possible. In practice, map generalization is a process of mutual restriction and trade-off of various influencing conditions, cartographic experts consider all the three aspects and balance them to reach reasonable results, sometimes they delete the small details on building's outlines, but it results in the area difference, sometimes they displace some points of the edges so that the area stays unchanged, but the vertices' location changes. It depends on the short-edge structures and distributions. By imitating this thinking and operation process of cartographers, a method based on short-edge structure recognition and progressive simplification is proposed.
      Methods  Firstly, the building outline is preprocessed. Then the contour segments are grouped, and the edge structure is identified and analyzed. After this, some specific situations are analyzed in detail, and the calculation region (the sequence of vertices associated with the simplification of a set of edges less than the tolerance) is used to determine the optimal simplification method. Lastly, the area difference is distributed to the whole building so that the building's area difference is reduced while the shape is maintained.OpenStreetMap (OSM) buildings are selected in the experiment.
      Results  Experimental results show that the proposed method can effectively reduce the number of graphic vertices, enhances the shape characteristics like parallel, right angle, etc. Also, the approach can control the area differences after generalization.
      Conclusions  The proposed method gives consideration to three aspects of the building simplification principles and balances them, which provides a new way for building simplification.

     

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