Performing Geographic Information System Analyses on Building Information Management Models
Abstract: As the usage of both BIM (Building Information Modelling) and 3D-GIS (Three-Dimensional Geographic Information Systems) has increased within the field of urban development and construction, so has the interest in connecting these two tools. One possibility of integration is the potential of visualising BIM models together with other spatial data in 3D. Another is to be able to perform spatial 3D analyses on the models. Both of these can be achieved through use of GIS software. This study explores how integration of BIM and GIS could look. The goal was to perform typical GIS analyses in 3D on BIM models. Previous research points towards some success within the field through use of the indicated standard format for each tool – IFC (Industry Foundation Classes) for BIM and CityGML (City Geographic Markup Language) for GIS. Transformation between the formats took place through use of the BIM software Revit, the transformation tool FME and the GIS software ArcGIS. A couple of reviewed applications of GIS analyses were chosen for testing on the converted models – indoor network analysis, visibility analysis and spatial analysis for 3D buildings. The input data in the study was several BIM models, both models created for real-life usage and others that only function as sample data within the different software. From the results of the practical work it can be concluded that a simple, automated and full-scale integration does not seem to be within reach quite yet. Most transformations between IFC and CityGML failed to some extent, especially the more detailed and complex ones. In some test cases, the file could not be imported into ArcGIS and in others geometries were missing or existing even though they should not. There were also examples where geometries had been moved during the process. As a consequence of these problems, most analyses failed or did not give meaningful results. A few of the original analyses did give positive results. Combining (flawed) CityGML models with other spatial data for visualisation purposes worked rather well. Both the shadow volume and sightline analyses did also get reasonable results which indicates that there might be a future for those applications. The obstacles for a full-scale integration identified during the work were divided into four different categories. The first is BIM usage and routines where created models need to be of high quality if the final results are to be correct. The second are problems concerning the level of detail, especially the lack of common definitions for the amount of details and information. The third category concerns the connection between local and global coordinate systems where a solution in form of updates to IFC might already be in place. The fourth, and largest, category contains those surrounding the different formats and software used. Here, focus should lie on the transformation between IFC and CityGML. There are plenty of possible, future, work concerning these different problems. There is also potential in developing own tools for integration or performing different analyses than those chosen for this thesis.
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