Helsinki is Building a Digital Twin of the City

City digital twin

The capital of Finland first tested city modeling as long back as 1987. But the most recent model of the Kalasatama district demonstrates the new state-of-the-art possibilities of this technology: creation of a highly accurate digital twin of the city.

My hosts, Helsinki’s city modeling specialists Jarmo Suomisto and Enni Airaksinen, showed me their latest projects. One of them offered a glimpse of history through a lens of the future.

With 3D glasses on, I was able to experience the unrealized city plan made by Eliel Saarinen, the father of the world-renowned architect Eero Saarinen. The virtual model in question was a digitized version of a huge physical model from 1915. Being able to stroll the streets and fly over the roofs of the imagined city really made me understand how awesome the original design was. I had seen a scale model of this same plan while it was laid in the foyer of the Museum of Finnish Architecture many years ago, but this experience was quite different.

The makers of the virtual Saarinen model, the Helsinki 3D+ team, used the same technique as they would use with a real-sized city. They took 3000 photos and programmatically turned them into a point cloud and further into a triangular mesh. In the case of digitizing the real Helsinki, an airplane took over 42,000 pictures at 1.2 kilometers height, all with astounding accuracy. The length of a pixel in those photos equated to 7.5 centimeters (3 inches) on the ground.

The digitized version of Eliel Saarinen’s 1915 scale model

The Helsinki 3D+ Team

Helsinki 3D+ is an ICT development project that was started in 2015. It is now a full-time job for a team of three mavens.

Architect Jarmo Suomisto and Kari Kaisla have jointly over 60 years of experience in 3D modeling and geospatial information management. Kaisla created the first comprehensive model of Helsinki back in 2001. Enni Airaksinen, City Model Specialist and MSc, joined the team recently after graduating from the Aalto University. She’s one of the few CityGML specialists in Finland.

Helsinki 3D+ is not a traditional city survey or planning service. It is a tool that can collaborate across all multiple functions of the city for whenever the use of a city model could provide value. Suomisto mentions education and social services as two examples. “City models are not just PR. They have a role to play in solving universal urban problems,” he says.

From left: Kari Kaisla, Enni Airaksinen, Jarmo Suomisto

The Kalasatama Project

Kalasatama is a new seaside district being developed in Helsinki. A smart city project called Fiksu Kalasatama has been experimenting with smart services in collaboration with the residents, businesses, and other stakeholders in the area. Helsinki 3D+ and Forum Virium, an innovation unit of the city, joined forces to serve the needs of the experimenters through the development and use of digital twins.

The Kalasatama digital twin project got funding from KIRA-digi, the national digitalization program of the Finnish government. The project team worked full time for over a half year to complete five critical tasks, namely to:

  1. Create digital twins of the Kalasatama development.
  2. Share the models as open data.
  3. Provide a virtual platform for the experiments that are part of the Fiksu Kalasatama project.
  4. Test new technologies, especially those related to CityGML.
  5. Advance the use of digital twins in the city’s processes and services.

“We created two city models, for which we used the very latest technologies available. The first one is a triangular mesh that is more detailed than the comprehensive Helsinki model. The other is a CityGML model. We included several new themes, like planned buildings and bridges,“ Airaksinen explains. “It is possible to expand the same processes to cover the whole city in the future.”

CityGML is a global standard established by OGC (Open Geospatial Consortium). It is a semantic, expandable information model that can describe objects—e.g., buildings and building parts—and their relationships in a hierarchical structure. CityGML makes the model “intelligent,” rather than just a three-dimensional representation of the reality.

CityGML Architecture
Kalasatama CityGML architecture

Digital twins are also a hot topic in building construction and operations. Combining city and building digital twins in the same model would make sense, but is not straightforward. Current BIM and GIS standards don’t support this union, and Suomisto predicts it may take years before it happens.

One of the key results from the KIRA-digi project was the documentation of the model creation and utilization process. The project team have described the process and use cases in a comprehensive project report that is going to be made available online, both in Finnish and English.

Many Uses

“Our primary purpose was not to create virtual entertainment or pretty pictures. Our aim was to increase the understanding of various phenomena and issues; to simulate, anticipate, and optimize,” Suomisto proclaims.

Because the digital twin data is open for anyone to use, the city and businesses alike can create new services based on it. Helsinki’s Energy and Climate Atlas, for example, uses the million semantic surfaces of 80,000 buildings to calculate and visualize the city’s solar energy potential.

My hosts also showed how they used digital wind analysis software to assess the effect of wind on the high-rise buildings of Kalasatama. The software can replace costly wind tunnel analyses and is already used in the auto industry.

Wind analyses
Kalasatama wind analysis

Helsinki 3D+ had earlier created a portal to visualize Kalasatama development projects. Citizens could study the area in 3D and add feedback with a mobile device. The same system is now used in other projects as well.

“What we’ve done here in Helsinki has aroused interest in cities around the world. We’re facing the same challenges of climate change and the quality of life as they are, “says Suomisto. “We’re not competitors in a business sense. Instead, we’re networking and collaborating with other cities and sharing our work with open data standards and open source tools with everybody.”

To learn more about Helsinki 3D+ and to experience the city models, visit

UPDATE: You can now download the report The Kalasatama Digital Twins Project.

The images are courtesy of the city of Helsinki.

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