Implications of Automated Height Extrusion and the Selection of Height Reference for LoD 1 SmartKADASTER City Model

Abstract

This paper discusses the lessons learnt from the SmartKADASTER Phase II city model development project, specifically on the reconstruction of the LoD 1 CityGML models. The LoD 1 models were reconstructed using automated height extrusions, either by creating categorised point clouds or by employing a raster-based equation such as CHM=DSM-DTM. The methods for reconstructing the LoD1 are further elaborated in this study. However, due to the particular nature of Malaysian buildings and inaccurate point cloud classifications, automated height extrusion alone was found to be insufficient to achieve the typical recommended average rooftop height as the LoD1 height reference. Additionally, it was determined that the recommended height reference is also unsuitable for cadastre-based analysis and other beyond cadastre purposes in Malaysia. As a result, this paper will discuss the selection of the LoD1 height reference and suggest the approach to ensure accurate height extrusion of the LoD1 model can be met. Finally, it is hoped that this work will contribute to the body of knowledge by appropriately referencing their 3D models for analysis purposes and raising readers’ awareness of the SmartKADASTER application system.