Improving integration between BIM and GIS

A transformation engine for IFC-BIM models into semantically enriched 3D CityGML building models, both exterior and interior

Ordnance Survey developed a transformation engine for strict and automatic mapping of IFC-BIM models into semantically enriched 3D CityGML building models, both exterior and interior. This work was completed with National University of Singapore (NUS) for the National Research Foundation (NRF) under the Virtual Singapore (VSG) programme.

Prior to this research project, between 2015-16, Government Technology Agency of Singapore (GovTech), OS and Singapore Land Authority (SLA) collaborated on a data model to store 3D building information from the data that SLA had captured through remote survey for the buildings in Singapore. The result contributed towards Virtual Singapore, aimed at creating a 3D digital representation of the urban landscape

The research was completed with the help of Singapore agencies Housing & Development Board (HDB), Building and Construction Authority (BCA) and Singapore Land Authority (SLA) who shared on the challenge of enhancing the building models in Virtual Singapore 3D with more geometric and semantic detail for both exterior and interior of buildings from IFC models. The outcome from this collaboration is an IFC2CityGML transformation engine that can be configured to satisfy the requirements for different geospatial use cases from IFC models.



The challenge was to take the information “locked away” in BIM models and make it available to wider stakeholders to help them make better decisions.

BIM contains a lot of information on a building used during the construction and maintenance of it, which is often “locked away” in proprietary software and formats. Only some of this information is potentially useful.

BIM platforms lack the tools and analytics functions necessary to make it available to city planners or regulatory bodies who would benefit from the data to test new developments or city planning initiatives.

Aerial view of Singapore


Ordnance Survey engaged with potential users of the “locked up” BIM data to find out which data could be used, the best format and the application of it. The users were regulatory bodies, city planners, emergency service response teams and building owners.

Based on the findings, Ordnance Survey developed the IFC2CityGML transformation engine. The rules based conversion software can transfer detailed building model information from IFC to an enhanced CityGML data model, which can be configured for different geospatial use cases.


The IFC2CityGML transformation engine uses an open 3D data standard so that data can easily be used and integrated, supporting advanced analytics and use cases, outside of proprietary software.

The rules-based approach enables automated reuse of the conversion process for different geospatial use cases and scenarios from IFC models.

The information stored in the BIM models can be used and managed for the lifecycle of the building, helping the industry to manage archive BIM models more easily.

The stakeholders are keen on understanding and implementing this use case approach in future developments for geospatial platforms and applications.

The project has also helped to improve understanding and collaboration across the BIM and GIS community in Singapore.

"This project successfully developed a conversion engine and rule set that is able to convert BIM IFC models into CityGML format, not only geometrically but also semantically, including interior structures. Ordnance Survey’s contribution was primordial in adopting a ‘use cases’ perspective to guide the research and development, benefiting a wide range of geospatial scenarios."

Rudi Stouffs, Associate Professor & Deputy Head (Research), National University of Singapore

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