https://andreasplesch.github.io/3d-tiles-examples/

selection:

https://andreasplesch.github.io/3d-tiles-examples/migration/output_from_1.0/Tilesets/Tileset/tileset.json
https://andreasplesch.github.io/3d-tiles-examples/migration/output_from_1.1_explicit/MultipleContents/MultipleContents/tileset.json

area in radians:
    "Longitude": {
      "minimum": -1.3196959060375169, -75.6149
      "maximum": -1.3196607462778132 -75.6131
    },
    "Latitude": {
      "minimum": 0.6988590050687061, 40.04290
      "maximum": 0.6988864387845588  40.04463
    }

basemap: https://github.com/earthstruct/x3dom/wiki/3D-Tiles#basemap