Abstract
Abstract. The trend of increased usage of both BIM and 3D GIS and the similarity between the two has led to an increase in the overlap between them. A key application of such overlap is providing geospatial context data for BIM models through importing 3D GIS-data to BIM software to help in different design-related issues. However, this is currently difficult because of the lack of support in BIM software for the formats and data models of 3D Geo-information. This paper deals with this issue by developing and implementing a methodology to convert the common open 3D city model data model into the most common open BIM data format, namely CityGML (Gröger et al., 2012) to IFC (buildingsmart, 2019b). For the aim of this study, the two standards are divided into 5 comparable subparts: Semantics, Geometry, Geographical coordinates, Topology, and Encoding. The characteristics of each of these subparts are studied and a conversion method is proposed for each of them from the former standard to the latter. This is done by performing a semantic and geometrical mapping between the two standards, converting the georeferencing from global to local, converting the encoding that the two standards use from XML to STEP, and deciding which topological relations are to be retained. A prototype implementation has been created using Python to combine the above tasks. The work presented in this paper can provide a foundation for future work in converting CityGML to IFC. It provides an insight into the relationship between the two standards and a methodology for the conversion from one to the other, and the process of developing software to perform such conversion. This is done in a way that can be extended for future specific needs.
Highlights
Since 2008 there was an increase in the use of Building Information Modeling (BIM) within the construction industry
This paper aims to address this issue by providing a methodology to convert the common open 3D city model data model into the most common open BIM data format, namely CityGML (Gröger et al, 2012) to IFC
The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Volume XLIV-4/W1-2020, 2020 3rd BIM/Geographic information systems (GIS) Integration Workshop and 15th 3D GeoInfo Conference, 7–11 September 2020, London, UK. Both CityGML and IFC provide a representation of different aspects of 3D models, including semantics, geometry, topology, and appearance
Summary
Since 2008 there was an increase in the use of Building Information Modeling (BIM) within the construction industry. Geographic information systems (GIS) have been increasingly used to generate detailed 3D data, and in particular 3D city models Both GIS and BIM can, provide 3D data, but they differ in terms of their characteristics and focus. The trend of increased usage of both BIM and 3D GIS and the similarity between the two has led to an increase in the overlap between them Both CityGML and IFC provide a representation of different aspects of 3D models, including semantics, geometry, topology, and appearance. Encoding: CityGML is an application schema for GML 3 that is based on XML It provides a common definition of basic entities, attributes, and relations of a 3D city model. In CityGML, objects can be represented in five different levels of detail, where objects become more detailed with the increased LOD and it differs regarding its geometry and thematic representation
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