A city can be considered made up of two dimensions: the physical dimension, which incorporates its geography and infrastructure, and the social dimension, which incorporates its citizens and culture. This has been the way of cities for as long as there have been people calling them home. However, as we move into the second quarter of the 21st century, there is global recognition of a third dimension: the digital dimension.

So many activities that constitute the fabric of a city – city planning, financial transactions, social exchanges, real-time transit updates, and more – now occur in the digital world. So it should be of no surprise that there is now a global movement to harmonize and democratize these virtual happenings by creating interoperating digital platforms where decision-makers and other stakeholders can monitor, simulate, predict, and plan the present and future state of their city. These platforms have come to be known as Urban Digital Twins, and they provide a critical interface and organizational tool for smart city technologies.

But before we get to “urban” digital twins, let’s briefly discuss where the concept of a “digital twin” comes from. We’re all aware that product design – whether that’s a jet engine or a sports shoe – takes place in a digital environment. But more than just being a 3D sketch of an object, products are also modelled in 3D environments that allow the designer to test how the product will behave under simulated real-world conditions. With the huge leaps in processing power and bandwidth seen over the previous decade, we have now scaled the concept of “digital twins” up to the city level. Indeed, urban digital twins are already transforming how cities are being planned, built, and managed. Working examples now appear in cities across the world, including Helsinki, Dublin, Singapore, Sydney, Wellington, and more.

Digital Twins at Urban Scales

Urban digital twins include static point-in-time 3D models of a city’s physical objects in tandem with dynamic predictive models of their behaviour that are driven by real-time inputs from city-wide sensors. Such sensors and models represent in the ‘digital dimension’ changes to the ‘physical dimension’ of the city – such as water levels of its rivers, wind speeds, how full its trash cans are, or real-time transit positions – as well as the ‘social dimension’ of the city – such as how crowded a train carriage is, what type of business a building houses, or what major cultural events are happening. More than just a tool for city managers, well-designed urban digital twins will comprise many different systems that together form a diverse, interoperable, accessible, inclusive, and secure data ecosystem within which many different players can obtain insight that improves decisions.

However, urban digital twins are not a “solved problem.” Along with increased investment in research and development, the vision demands agreed-upon methodologies and standards, new commitments to data-sharing, -privacy & -ethics, forward-looking regulations, and the development of a robust global community that is as devoted to tradecraft as it is to technology.

The Location Powers: Urban Digital Twins virtual summit

These were some of the issues addressed at the Location Powers: Urban Digital Twins virtual summit held January 12-14, 2021. The summit brought industry, research, and government experts from across the globe together into an interactive discussion that assessed the current “state of the art” and produced recommendations for future technology research, innovation, and standards development in support of urban digital twins that adhere to the FAIR data principles of Findability, Accessibility, Interoperability, and Reusability.

Held over both eastern- and western-friendly time zones, speakers and participants were drawn from diverse fields of expertise, including: urban geography; planning; governance; civil engineering; BIM; geospatial; the design, modelling, and operation of physical infrastructure; data science; machine learning and artificial intelligence; cloud/edge/fog computing; and more. Speakers presented on existing projects, experiences, best practices, and promising research surrounding urban digital twins – including applications in transport, utilities, energy, health, and more. 

To realize the promise of urban digital twins, summit participants agreed that governments, researchers, and industry must collaborate on three overarching priorities that will provide a foundation for successful urban digital twins: research and development; standards development; and community involvement.

Research & Development
Participants identified several key areas that require research and development to help planners and practitioners maximize urban digital twins’ potential as well as remove barriers currently hindering adoption and execution. Such areas include: cultivation of digital twin base layers, including those for underground and indoor models; best practices for making models dynamic and current, including simplifying integration of disparate data from heterogeneous sources, such as sensors; co-creation for coordinating planning using multiple urban digital twins; development of digital twins for social use-cases, such as mobility, public health, and justice; data model linkages; and data sharing with an eye for security and privacy. The recommendations and outcomes of the Location Powers Summit will now feed into OGC’s Innovation Program, where OGC Members come together to solve just these types of geospatial challenges via a collaborative, agile process. Indeed, the Innovation Program has been maturing relevant technological concepts, such as smart cities, urban platforms, and system-of-systems approaches, through previous Testbeds, Pilots, and Initiatives including ESPRESSOThe Smart City Interoperability Reference Architecture (SCIRA) Pilot, The 3D IoT Platform for Smart Cities Pilot, and more.
Standards Development
From a technical standpoint, open standards play a critical role in urban digital twins to not only improve accessibility and functionality, but also reduce costs and increase value. Further, like any digital concept, Standards are required before urban digital twins can mature. The value of open standards to government, industry, academia, and wider society is a message that OGC has firmly believed in and promoted for its 25+ years of existence. As such, OGC offers a suite of open standards of use and benefit to urban digital twins: including CityGML, IndoorGML, SensorThings, 3DTiles, i3S, and our new OpenAPI-based OGC API standards. However, it’s still early days for urban digital twins, and OGC is actively working to lay the foundations that will allow the technology to mature.Two areas identified by the summit participants as requiring further standards development or improvement are standards for linking data models, and for capturing and sharing specialized data sets such as for energy, water, underground infrastructure, and mobility. The knowledge gained from the discussions held at the Location Powers Summit will now feed into the OGC Standards development process with the aim to improve existing, or develop new, consensus-based data standards.
Community Involvement
Successful urban digital twins require ongoing collaboration between multiple tiers of government, the private sector, public utilities, building owners, community groups, citizens, and more. Just like standards, urban digital twins will only work if they are designed to accommodate diverse – and often unforeseen – viewpoints and use-cases. Capturing and promoting best practices (as well as lessons learned) from across the globe can help ease the creation of urban digital twins while also promoting novel use-cases that may not otherwise be known to be possible. Some examples presented during the Location Powers Summit included: providing ‘blueprints’ and best practices that can help in the scaling of urban digital twins from prototype to reality; deploying energy digital twins to assist with cities’ carbon-neutral objectives; using visualization and gamification to generate interest and demand for urban digital twins; and building training and education programs to develop a next-gen workforce that is fluent in creating and deploying urban digital twins. The OGC Community already has mechanisms for this type of knowledge sharing, as we have proudly cultivated a “neutral ground” where different viewpoints and perspectives from across industry, government, and academia can share knowledge and experience, and help build the open, consensus-based standards that OGC is famous for.

OGC, as the connector for all things location, is in a unique position to bring together experts from the many different technology application areas that will constitute the urban digital twin data ecosystems. From the cloud providers, to the software engineers, to the predictive model builders, to the sensors builders, to the users and decision-makers, the OGC Community can work together to create and pilot open, consensus-based Standards, best-practices, reference architectures, and more, while providing the necessary fora for the many different stakeholders to meet and provide inputs and perspectives. 

The promise of urban digital twins aligns well with OGC’s vision to build the future of location with community and technology for the good of society, and our mission to make location information Findable, Accessible, Interoperable, and Reusable (FAIR), so come meet and join our community and help create the foundations for urban digital twins that will help humanity live in cities that are safer, more sustainable, more resilient, and more responsive to their occupants.


BIM, Digital Twins, IoT, Smart Cities