Case study

Digital twins offer a powerful solution to fragmented systems, enabling a single source of truth for smarter, more connected and resilient cities.

Tokyo Digital Twin

Building the Tokyo Digital Twin with TerriaJS and Cesium ION

Tokyo, a metropolis of around 14 million people, constantly evolving, faced a monumental task: how to unify its sprawling urban information into a single, understandable view. The answer came in the form of an advanced, interactive geospatial platform, known as the Tokyo Digital Twin. This wasn't just about mapping streets; it was about building a dynamic, real-time reflection of the city, empowering officials and citizens alike.

Tokyo Digital Twin Project presentation at the Cesium Developer Conference, June 2025

The visionary team at Pacific Spatial Solutions and Mitsubishi Research Institute working in close collaboration with the Tokyo Metropolitan Government, embarked on this ambitious journey. They chose TerriaJS and Cesium ION, a powerful combination of o technologies to be the bedrock of a project that would redefine urban planning and disaster preparedness.

Tokyo Flood Control Channel River monitoring camera (live capture)

Goals and Vision

Through the Tokyo Digital Twin Program, The Tokyo Metropolitan Government initiated the Digital Twin project with the following primary objectives:

  • Visualize complex urban data from various departments in an integrated 3D environment.

  • Support disaster preparedness and response planning, particularly for earthquakes and floods.

  • Enhance transparency and collaboration with the public and private sectors through open data.

  • Accelerate smart city initiatives by providing a platform for urban simulation and scenario planning.

Why TerriaJS?

Its open-source nature provided Tokyo with unparalleled control and the freedom to customize the platform to its specific needs, a crucial advantage in a project of this scale. TerriaJS's robust 3D visualization capabilities, seamlessly integrating with Cesium ION for stunning terrain and building models, were essential for creating an immersive and accurate representation of the city. 

The platform’s flexibility in handling diverse data formats – from WMS and WFS to 3D Tiles, GeoJSON and live data streams – meant that no valuable dataset would be left behind. Crucially, its ease of integration with existing government data portals and GIS workflows ensured rapid deployment, enhancing investments in current capabilities. 

Implementation Highlights

Data Integration

Tokyo’s digital twin integrates datasets from various sources:

  • Real-time sensor data (e.g., weather, traffic)

  • BIM and 3D urban models

  • Disaster simulation outputs (e.g., flood zones, seismic intensity)

  • Open data from city planning, infrastructure, and demographics

These datasets are layered in a coherent geospatial interface that allows users to toggle visibility, filter information, and query specific regions.

3D Visualisation

TerriaJS, combined with Cesium ION, enabled the development of an immersive 3D representation of Tokyo:

  • Buildings are visualized in detail using 3D Tiles.

  • Simulation overlays (e.g., tsunami inundation) appear directly over the terrain.

  • Users can switch between 2D and 3D views seamlessly.

It brings together the 3 key ingredients of a spatial digital twin: the built environment, the natural environment and live data. 

Integration of vegetation, buildings and underground data for Shinjuku Ward

User Experience and Accessibility

Recognising the diverse audience, from urban planners to everyday citizens, the user experience was crafted for intuition and accessibility. A responsive design ensured seamless functionality on both desktop and mobile devices. Bilingual support in Japanese and English bridged language barriers, while searchable location indexes and thematic maps offered quick access to vital insights.

Outcomes and Impact

The Tokyo Digital Twin has already demonstrated several key benefits:

  • Increased preparedness: Authorities use the tool for crisis simulations and risk communication.

  • Enhanced public engagement and trust: Citizens explore their neighbourhoods and understand risks through the web interface.

  • Cross-agency collaboration: City departments share consistent data layers, breaking down silos and duplication.

Shinsakongawa Water Park point cloud, Industry-Academia-Government FY 2022 data collaboration demonstration

Lessons Learned

Reflecting on this transformative project, several key lessons emerged. 

The modular architecture of TerriaJS, with its plugin-based structure, proved invaluable, allowing the project team to rapidly iterate and integrate new features as needs evolved. 

The power of open data was undeniable; by leveraging publicly available datasets, the project avoided expensive vendor lock-in and paved the way for broader use and a higher return on investment. 

And finally, the importance of visual clarity shone through. Terria's user-friendly storytelling and layering features made complex data digestible and accessible to diverse audiences, driving widespread adoption and engagement.

Conclusion

The Tokyo Digital Twin is a model example of using TerriaJS and Cesium ION to build scalable, open, and interactive urban platforms. It proves how modern geospatial tools can transform complex data into actionable insight, fostering smarter and more resilient cities.

Integration of population information and buildings data for Chiyoda Ward

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