Paper Conference

Proceedings of ASim Conference 2016: 3rd Asia conference of IBPSA-China, Japan, Korea


Workflow for Generating 3D Urban Models from Open City Data for Performance-Based Urban Design

Kian Chen, Leslie Norford

Abstract: Urban designers gather and interpret data in the early design stages for two purposes: first, to study similar projects as precedents; and second, to better understand existing site conditions. Interpretation includes the running of environmental analysis on the collected data. The results of the analysis are used as references for a performance-based urban design process. City data are usually available in 2D but environmental analysis requires 3D city data. A method is proposed for calculating the building heights from 2D data for generating 3D urban model. The method uses building footprint and Floor Area Ratio (FAR) data. For Singapore, OpenStreetMap (OSM) has the building footprint data, and the Urban Redevelopment Authority provides the FAR data. The average building height of each plot is calculated from the method. A 3D urban model is generated by extruding the footprint by the calculated average height. The 3D urban model is then used for environmental analysis. The calculation and analysis are integrated into a workflow for urban designers. Designers gather and assemble these data on the QGIS platform. Once assembled, the data is passed to the appropriate tools for 3D generation and analysis. The 3D urban model is documented in CityGML format. The solar photovoltaic energy potential is calculated using the CityGML model with the Daysim lighting simulation. A case study is presented as proof of concept. The 3D urban model with predicted height is compared with the actual height model. The workflow over predicted the building heights by 20%. The PV potential results between the two models differ by 4.72%. Further improvements are suggested for the workflow. These include considering terrain data and having a more comprehensive set of analyses.
Keywords: Performance-Based Design, CityGML, GIS, Open City Data, Workflow