Journal of Geo-information Science >
Organization and Management of Multi-scale 3D Buildings for Generalization
Received date: 2014-12-02
Request revised date: 2015-01-07
Online published: 2015-08-05
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With the rapid development of geographical information acquisitions methods, 3D city models are widely used now. Level of detail (LOD) is used to improve the performance of three-dimensional (3D) visualization. Management of multi-scale building data is important in 3D building generalization, and many scholars have studied the indexing model of multi-scale spatial data for 2D map. In order to satisfy the demands of massive spatial data in 3D city modeling, a new spatial indexing model named as GAMR tree (Generalization Area Multi-representation R Tree) is proposed to deal with the multi-scale model of 3D building. Based on the characteristics of 3D building generalization, impact factors for constructing the 3D building generalization areas are analyzed in this paper. Next, the generalization areas are divided into four types which are denoted as big city, city, town and village. As a result, different generalization methods are adopted for the generalization of different areas. In this research, GAMR tree is defined based on the structure of R-Tree while assigned with different node types. Two indexing trees, which are named respectively as the generalization R tree and the child tree of generalization area, are included in the new indexing model. The leaf node of the child tree is consisted of two items, one is the MBR that representing the building ground area, and the other is the corresponding 3D building model for that area. While the branch node is consist of a MBR that accounts for the total area of its child nodes, and pointers that connect to its child nodes. The children trees are generated by a bottom-up method, and the height of a tree is determined by the threshold calculated in generalization. Multi-scale querying method of GAMR tree is furthermore proposed in this paper, and the steps of a rectangle querying instance are presented. Considering the variations of projected length caused by different sight directions, the corresponding LODs of building models that organized by GAMR tree is well determined and chosen to be displayed on the screen, so that the projection of building features can be recognized by users. Generally, the experiment has proved that this spatial indexing tree works well in 3D building generalization and multi-scale representation.
GE Lei , LI Jiansheng , WANG Junya . Organization and Management of Multi-scale 3D Buildings for Generalization[J]. Journal of Geo-information Science, 2015 , 17(8) : 889 -894 . DOI: 10.3724/SP.J.1047.2015.00889
Fig. 2 Structure of GAMR tree图2 GAMR树的结构 |
Fig. 3 Variations of projected length caused by different sight directions图3 视线方向对投影长度的影响 |
Fig. 4 3D building models organized by GAMR tree图4 GAMR树管理的三维建筑模型 |
Fig. 5 The querying result of a building that displayed at a certain scale图5 某尺度下建筑对象的查询结果 |
The authors have declared that no competing interests exist.
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