Directions: 3D Tiles 2.0 on glTF 2.1

Read on 2026-11-02. Every spec below is a draft and the streaming work in cesium-native is not merged, so names and details may change. For glTF 2.1 core, see glTF 2.1 — Complex Scenes.

Nothing needs to change in 3dtiled today. Its 3D Tiles 1.1 output is the format to keep writing, and a 2.0 writer should wait until cesium-native's loader leaves draft.

What 3D Tiles 2.0 is

A tileset becomes a glTF 2.1 file. Tiles are nodes carrying 3DTILES_tileset, and subtrees are glTF too, through 3DTILES_subtree. The entry file should be named root.tileset.gltf or root.tileset.glb, must have one scene with one root node, and every node carries the extension.

The drafts are on CesiumGS/glTF, branch 3d-tiles-2.0, under extensions/2.1/Vendor:

glTF 2.1 core is tracked in KhronosGroup/glTF#2585.

State of cesium-native

v0.66.0 (2026-11-02) can read and write these extensions through generated classes (#1451), but it cannot stream such a tileset yet.

Streaming is tracked in #1453, as a stack of open pull requests:

External assets are tracked separately in #1465.

This page only covers cesium-native. Support in CesiumJS and 3DTilesRendererJS has not been checked.

What it means for 3dtiled

1.1 output. Every converter and live endpoint writes asset.version: '1.1', and core/tiling.js writes binary .subtree files. #1467 replaces cesium-native's subtree class and converts the old format on the way in, so regressions there would hit implicit tilesets first. COPC and Potree output would make good test cases once it lands.

Where each draft would land:

packages/3dtiles-tools/upgrade.js may look like the natural home for a 1.1 → 2.0 step, but it is mostly per-tile conversion (b3dm and pnts to GLB), while 2.0 restructures the tileset itself.

EXT_georeference supersedes the 3DTILES_georeference draft noted in Future work. It places a node at a longitude, latitude and height on the ellipsoid, with local -x east, +y up and +z north. The node's own transform is applied first, so a heading goes there. That maps closely onto /stream's placement parameters, and the extension is optional, so it could be added alongside the tile transform without affecting other readers.

Compression passes the stricter decoding in v0.66. These were memory-safety fixes for malformed files (#1446, #1447, #1460). A one-off check ran compressGlb on 12 synthetic cases, Draco and meshopt across meshes and points, with RGB and RGBA colours in 8 and 16 bits, tangents and 16- and 32-bit indices:

This checks the format only. The output was not loaded in cesium-native, and no real tiles were used.

Splats stay as they are. cesium-native's classes cover KHR_gaussian_splatting and KHR_gaussian_splatting_compression_spz_2, which is what 3dtiled writes. CESIUM_DISABLE_SPZ (#1438) is a build option that removes the SPZ decoder, for applications that don't want it. No converter writes EXT_splat_opacity.

Clipping. cesium-native#1486 requests clipping geometry by box or polygon. Crop and extract here are server-side and don't depend on it.

Open question

The Blender add-on built on cesium-native selected 0 tiles on two local, non-georeferenced 3dtiled tilesets (clipping off, view pivot at the origin, 60 m), where the same output had selected 26 tiles the day before. So it may depend on the view, and the add-on's local-placement camera conversion is the first suspect. One lead on this side, not confirmed: rad-to-3dtiles gives its root an RX(180°) transform, which a camera conversion could mishandle.

When to act

• #1467 merges: test COPC and Potree implicit output against it.
• #1478 leaves draft: design the .tileset.gltf writer.
• EXT_georeference stabilises: emit it on /stream tiles alongside the transform.