Gaussian Splats and 3D Mesh for the City of Liestal

For its urban planning, the city of Liestal wanted an up-to-date, detailed 3D model of the entire urban area. The data was to serve as a common basis for planning its districts.

Using a helicopter, we captured the 6.65 km² area with nadir and oblique imagery, meaning photos taken straight down and at an angle toward the facades. In total, more than 10,000 images were captured at a resolution of 3 cm per pixel. This means that one pixel in the orthophoto covers a square measuring 3 cm on each side in the real world.
From this imagery we computed a textured 3D mesh, prepared in tiles of varying edge length and multiple LOD levels, detail levels that load depending on viewing distance. For the icRoom by Inside Reality, a projection that turns three walls of a room into a single image using multiple projectors, we developed a dedicated workflow together with the manufacturer.

The triangle count was optimized, and the surfaces were then split by slope into roofs and streets, facades, and undersides. Each group received textures at the appropriate resolution, allowing the model to run live in the icRoom at 60 frames per second. The workflow can now be applied to project areas of any size. Gaussian Splats, photorealistic 3D scenes computed from the aerial images, were also produced from the same data.

For the Sichtern district, we additionally created a Cesium tileset, a web format for streaming 3D data, connected to the platform LUUCY. Volumes designed in LUUCY are transferred to the icRoom at the push of a button.

The city of Liestal uses the data to plan its districts and reviews proposals directly in the photorealistic model, on screen in LUUCY and room-filling in the icRoom.