面向城市DEM构建的地形要素分类及表达

地形要素是对地形在地表的空间分布特征具有控制作用的点、线或面状要素,其合理划分可为城市地形建模提供数据基础。本文在解析城市地形特征和分析现有地形图分类在城市DEM建模中不足的基础上,基于面向对象思想,以城市地形被城市道路网分割为基本原则,构建了城市地形要素分类及表达方法,并以南京市某区1:500地形图为实验数据,进行了相关验证实验与分析。实验结果表明,本文提出的地形要素分类和表达方法能够整体控制并有效表达集几何和语义信息为一体的复杂城市地形,在全局和局部地形上均有较好的建模效果。本文提出的城市地形要素分类及表达方法不但可为地形要素的分析和应用提供基础,也可为城市地形构建模拟、建设规划和分析决策等提供技术支撑。

Classification and Expression of Urban Topographic Features for DEM Construction

Topographic features are defined as point, polyline and polygon elements which control surface topography of the earth. Its reasonable classification can provide the data foundation for the simulation of urban topography. There are already many industrial standards for topographic map classification. However, the existed feature classification and coding methods are mainly focused on surveying, mapping, editing, updating, and data storage of topographic map. These methods cannot be used for urban DEM construction directly. After parsing the characteristics of urban terrain and analyzing the deficiencies of classification method in urban terrain modeling based on large scale topographic map, a classification and expression method of urban topographic features is put forward in this paper. According to the principle of urban space is divided by road and land parcel, the topographic features of urban terrain are classified and expressed with mathematical equations based on object-oriented thought by taking the 1:500 topographic maps as fundamental data. To test and verify the effectiveness and feasibility of the classification and expression method, this paper made a registration between classification results and remote sensing images, constructed the DEM and extracted the slope. Meanwhile, this paper performed a comprehensive evaluation for classification results from geometric and semantic perspectives. Also, it analyzed modeling effects at global and local scale, respectively. The experiment results showed that the classification results can be well matched with remote sensing images, the proposed classification and expression method of topographic features can express the geometric and semantic information of complex urban terrain effectively at both global and local scale. The classification and expression method of topographic features for urban DEM construction can not only provide basis for analysis and application of terrain factors, but also provide technical support for the application of topographic features, such as urban terrain modeling, construction planning and decision-making.