Abstract
Abstract. Task-specific applications demand abstractions (generalized) 3D scenes of 3D models to be used for visualization and analysis purposes. Therefore, lower LoDs (level-of-details) from higher LoDs need to be made available to these applications. A unified generalization framework is proposed to derive multiple LoDs (LoD3-LoD1) taking both semantics and geometric aspects of 3D buildings modelled in CityGML (City Geography Markup Language) into account. For this purpose, interior structures of 3D objects at LoD4 are removed to derive LoD3 and openings (door, windows) are removed from LoD3 to derive LoD2. Remaining parts such as outer installations and walls are projected onto the ground and simplified based on CityGML generalization specifications. Algorithms for simplification with the aim to derive LoD1 from LoD2 are implemented and tested on a number of buildings of Putrajaya city, Malaysia.The experiments shows that elimination of important part (s) or merging could be avoided by applying semantic-based removal of objects at different LoDs.
Highlights
Task-specific applications demand abstractions 3D scenes of building models to be used for visualization and analysis purposes
Our research focused on derivation of multiple LoDs of buildings modeled in CityGML taking semantics and geometric transformation of permanent objects into account
A number of tables are created in a relational 3D Geodatabase to store semantic objects and object parts such as and their corresponding geometries of a building retrieved from XML-based CityGML file
Summary
Task-specific applications demand abstractions (generalized) 3D scenes of building models to be used for visualization and analysis purposes. Simplification method proposed in (Sester and Brenner, 2004) and extended by (Fan et al, 2009) and (Mao et al, 2011) based on CityGML specification is suitable for simplification of 2D plans but could produce different results as simplification is carried out without taking differential changes and ratios into account. This year’s research conducted in (Fan and Meng, 2012) is related to simplification of simple structures like parallel and rectangle shapes and complicated structures like non-parallel, non-rectangular and long narrow angles shapes. The paper should have the following structure: 2. BUILDINGS MODELLED IN CITYGML AND GENERALIZATION SPECIFICATIONS
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