GLB (Binary glTF)

glTF 2.0 is the Khronos Group standard for transmitting 3D scenes, often called "the JPEG of 3D": a scene description, geometry and materials in the PBR model. GLB is its binary packing, where everything including buffers and textures sits in a single file. That is exactly why GLB became the default format for the web, for augmented reality and for quick model exchange.

The export is for when a 3D city has to show up in a browser or on a phone: an interactive model of a block on a website, an AR view of the development, a project presentation with no special software to install. GLB opens in the built-in Windows viewer and loads into three.js in a few lines.

Only buildings go into the scene. Every outline is extruded to its own height: first by the height tag, then by building:levels multiplied by 3 meters, and if neither is present, by a neutral default of about 9 meters. Optionally a base is added; where elevation data (DEM) covers the area, buildings and base follow the terrain.

Coordinates are meters relative to the center of the selected area, so the model arrives at real scale and does not fly off from the origin. Buildings are colored by development type with PBR materials, so in a viewer the scene looks meaningful straight away, with no manual setup.