Figures & data
Table 1. CityGML’s generalization specifications of different LoDs, adopted from Ref. (Citation2).
Figure 1. A framework for 3D generalization.
Figure 2. Workflow of the generalization within the framework of CityGML.
Figure 3. Simplification of offset taking length of neighboring edges into account: original edges of offset (a), extension of the larger edge and identification of shortest edge (b), and final result of simplification process (c).
Figure 4. Simplification of a segment with a sharp corner: Original corner formed by two large edges (a), creation of a triangle with center point (b), and simplified corner (c).
Figure 5. Removal of sharp corner: original shape of corner (a), reduction of longer edges (b), and the result of the removal of newly formed smaller edges (c).
Figure 6. Simplification of a building known as Mahkamah Persekutuan, Putrajaya, Malaysia: original building footprint (a) and simplified version (b).
Figure 7. Aggregation of simplified models: original building (a), simplified models (b), and aggregated models (c) visualized in LandXplorer CityGML Viewer 2009.
Figure 8. Derived coarse LoDs from left-to-right (LoD4–LoD1).
Table 2. Percentage of data reduction based on minimum length of generalized objects.
Figure 9. 3D building models of a portion of Putrajaya, Malaysia, visualized in LandXplorer CityGML Viewer 2009.
Figure 10. Generalization of 3D buildings: simplification models (left) and simplified and aggregated models (right).
Figure 11. Street views of generalized buildings from two different perspectives, visualized in LandXplorer CityGML Viewer 2009.
