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

Tokyo Flood Control Channel River monitoring camera (live capture)

Why TerriaJS?

TerriaJS is open-source, which provided Tokyo with unparalleled control and 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 Tokyo’s existing investments and capabilities. 

Integration of vegetation, buildings and underground data for Shinjuku Ward

Implementation highlights

Data integration

Tokyo’s digital twin integrates datasets from many 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 three key ingredients of a spatial digital twin: the built environment, the natural environment and live data. 

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.

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

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.

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.

Integration of population information and buildings data for Chiyoda Ward