Parity with quantized mesh

[lilleyse]

quantized-mesh is a predecessor of 3D Tiles for global scale terrain. This issue keeps track of the remaining work needed for 3D Tiles to have parity with quantized-mesh.

• Double headed quadtree - 3DTILES_implicit_tiling
• Tile header - Covered by implicit tile metadata and tile semantics
  • TILE_BOUNDING_SPHERE
  • TILE_MINIMUM_HEIGHT
  • TILE_MAXIMUM_HEIGHT
  • TILE_HORIZON_OCCLUSION_POINT
• Vertex data
  • Covered by glTF and mesh compression extensions e.g. EXT_meshopt_compression and KHR_draco_mesh_compression
  • Note: quantized mesh positions are quantized spherical coordinates while glTF is cartesian
• Skirt indices - https://github.com/CesiumGS/glTF/tree/cesium-terrain-edges/extensions/2.0/Vendor/CESIUM_tile_edges
• Oct-encoded normals - covered by glTF mesh compression
• Watermask extension. Two approaches:
  • Property texture in EXT_mesh_features + WATERMASK semantic + dynamically generated texture coordinates
  • Or store it per vertex
• Metadata extension - covered by implicit tile metadata

[runaas]

Shouldn't also "draping of textures from ImageryProviders like WebMapTileServiceImageryProvider" be in a roadmap like this?

[lilleyse]

@runaas - that is definitely of interest but would be part of the CesumJS roadmap unless there are specifics that need to make their way into the spec.

See CesiumGS/cesium#7591 for the CesiumJS issue