OptionalassetTileset asset metadata. gltfUpAxis declares the up-axis of this tileset's glb content
('Y' when absent, per the spec); it is read per tileset because an external tileset
carries its own asset and may differ from its parent.
OptionalextensionsRaw tileset-level extensions object.
OptionalextensionsExtension names declared used by this tileset (e.g. ESRI_crs); see detectVendor.
OptionalgeometricTileset-level geometric error (metres).
The root tile of the tree.
A parsed
tileset.jsondocument — the input to the engine constructors andparseTileset(typically obtained via resolveSource).