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Smart cities driving integration of BIM & geospatial

The Future Cities Pilot will support city services in the context of a 3D model.
The Future Cities Pilot will support city services in the context of a 3D model.

Simon Chester and Bart De Lathouwer from OGC explains the OGC Future Cities Pilot and the need for open and accessible spatial data standards when integrated spatial data is coming into city models from diverse sources.

With 54% of the global population living in cities — rising to 66% by 2020 — there is a real need for new and more efficient ways to manage cities. The vision of ‘smart cities’ — that is, effective integration of the human, social and physical environments with the digital systems that manage and represent them — will provide these new management tools, and make urban areas more prosperous, inclusive, sustainable, and resilient, and in the process, improve the quality of life of their residents.

But what does this integration look like? And how do we get there? One element that will aid in the management of smart cities are city models — 3D models of the city that are built from and include diverse data sources, including cadastre, as-built plans, LiDAR scans, aerial/satellite imagery, utility data, real-time air quality, traffic, etc. — that are used to enhance and improve the decision making within and about the city. With spatial data coming in to these models from diverse sources — different construction firms, government bodies, 3D/data providers, sensors, utility companies, social media, etc. — the requirement for open and accessible spatial data standards is critical. As such, the Open Geospatial Consortium (OGC) created a stack of interoperability standards, such as CityGML, IndoorGML, InfraGML and others.

About the OGC Future Cities pilot

The objective of the OGC Future Cities pilot project is to demonstrate how CityGML data and IFC data together can provide stakeholders with information, knowledge and insight to enhance financial, environmental, and social outcomes for citizens of cities.
One of the pilot’s scenarios — in the borough of Greenwich, England — will tackle fuel poverty and the provision of adult social services. It is felt that part of the solution to improving adult social services and addressing fuel poverty issues lies in ensuring that the built environment is age-friendly and well-maintained. A better understanding of the energy efficiency of the housing is required. A lot of data is available on the performance of homes, as is open geo-demographic data, but, there is a need for more specific data on individual homes, the link to household need, and potentially to real-time data on performance to identify need for increased or urgent care of those at risk and to improve social outcomes.

In another of the pilot’s scenarios — in the city of Rennes, France — the use of BIM models encoded in IFCs is mandatory for important building projects. The urban planning authorities check the conformance with urban planning rules using an automated process. For verification, an analyst views the building project within the existing 3D model of the city. The BIM data is added to the existing 3D city model’s database, according to local city rules, with mappings to the various levels of detail (LOD).

Maintenance of 3D city models

CityGML is an open data model and XML encoding developed by the OGC for the exchange of virtual 3D city models. The aim of the development of CityGML is to reach a common definition of the basic entities, attributes, and relations of a 3D city model. This is especially important with respect to the cost-effective sustainable maintenance of 3D city models, allowing the reuse of the same data in different application fields. CityGML was designed for use in the planning, operation, and management of cities, but for the actual design and construction of the buildings and civic projects that make up a city, detailed Building Information Models (BIM) are required. BIM is used in the design and construction stages to see how buildings will/do operate, but they don’t place the building in the wider city context. There is, thus, a divide between these two worlds, despite obvious overlaps.

Thankfully, there is already a well-established exchange format for BIM data; Industry Foundation Classes (IFC). IFC is a platform neutral, open file format specification that represents the buildingSMART data model specification, an open international standard for BIM data. An IFC dataset coming from a BIM can be appropriately stripped back (lowering its LOD, in the industry parlance) before it’s transformed and imported into a city model.

Interoperability between IFC and CityGML

Ultimately, smart cities could improve the currency of their city models by using as-built IFC provided by those constructing new buildings, perhaps as part of the building permit process, but how this will work is yet to be determined. With this in mind, OGC is collaborating with buildingSMART International (bSI) to demonstrate the interoperability between IFC and CityGML in its Future Cities Pilot program.

Tackling bidirectional translation

IFC data will be exchanged among the various Future Cities Pilot participants in building construction or facility management projects. Semantic augmentation of the model is common across the IFC and CityGML encodings. The two standards organizations are also tackling bidirectional translation between IFC and CityGML, which will further improve the built workflow.

OGC is also working with other standards development organizations to converge BIM, 3D, and geospatial standards. ISO/TC 59 Buildings and civil engineering works, buildingSMART, and the OGC are coordinating for the development of standards as a foundation for the convergence of building and civil engineering design and geospatial technology. Other relevant organizations include the Mortgage Industry Standards Maintenance Organization (MISMO), the National Institute of Building Sciences (NIBS) and OSCRE International.

The focus of the pilot is on the integration of building and geospatial information as well as social services. Technology providers participating in the Future Cities Pilot will learn city requirements, show the providers’ interoperability capabilities, and have the opportunity to influence standards development.

This last point shouldn’t be overlooked: Interoperability between the geospatial and BIM worlds is an inevitable part of the smart cities of the future, OGC and bSI members will have a unique opportunity to guide the creation of the standards that will drive smart city initiatives, as well as influence their vision of the future.

Simon Chester
Communications Coordinator,
Open Geospatial Consortium

Bart De Lathouwer
Director, Interoperability Programs
Open Geospatial Consortium