minimal-pointcloud-gltf

a gltf 'profile' for an open format Point-cloud standard, leveraging glTF and 3d-tiles-next.

Point-Cloud profile

Recommended extensions:

• GLTF: EXT_meshopt_compression
• GLTF: KHR_mesh_quantization
• GLTF: KHR_materials_unlit
• 3DTILES: EXT_mesh_features
• 3DTILES: implicit_tiling

Creating a glb Tile:

1. point primitives only
2. only one node
3. single buffer
4. required buffer view for VEC3 positions (max size uint32) (do not break up into 65k buffer chunks)
5. optional buffer view for VEC4 RGB colors (max size uint32) (do not break up into 65k buffer chunks)
6. optional buffer view for VEC3 normals (max size uint32) (do not break up into 65k buffer chunks)
7. single material using extension 'KHR_materials_unlit'
8. finally, compress glb with GLTF_EXT_meshopt_compression (ie. try glTFpack )

Unlit Material example:

"materials": [
    {
      "name": "unlit",
      "extensions": {
        "KHR_materials_unlit": {}
      },
    }
  ],

Flower

• Source: SketchFab cc
• Using KHR_materials_unlit
• Compressed with MeshOpt Compression, based on this conversation
• glTF version: flower-pointcloud-MeshOpt_unlit gltf bin
• glb version: flower-pointcloud-MeshOpt_unlit.glb

single position & color buffer example:

"bufferViews": [
    {
      "buffer": 0,
      "byteLength": 200789448,
      "byteOffset": 0,
      "byteStride": 12,
      "name": "floatBufferViews",
      "target": 34962
    },
    {
      "buffer": 0,
      "byteLength": 267719264,
      "byteOffset": 200789448,
      "byteStride": 16,
      "name": "floatBufferViews",
      "target": 34962
    }
  ],

References

• all 3DTiles-Next extensions - https://github.com/CesiumGS/3d-tiles/tree/main/extensions
• convert from pointcloud 3dTiles v1.0 (PNTS-Draco) to 3dTiles v1.1 (glb-MeshOpt) I used this script: https://gist.github.com/wallabyway/d022f97191599c5d9dde4827aecec1e5

Demo

Add point-cloud to mapbox, via 3d-Tiles/glTF pointcloud file set

(watch this space)

three.js (ebeaufay)	Cesium (experimental)