3dtiled Supported Formats

Introduction: The intent (online, range-streamed)

This started as a set of Node.js SDK/CLI, standalone-packaged, converters: take a tiled / LoD source format — HLOD Hierarchical Level of Detail, tiled point clouds, meshes, or 3D Gaussian splats (COPC, Potree, I3S, stream-SOG, LCC, RAD, 3MX, GeoSplats, …) — and turn it into OGC 3D Tiles 1.1 (standard mesh primitives, TRIANGLES, POINTS, splats via KHR_gaussian_splatting + KHR_gaussian_splatting_compression_spz_2 GLB tiles). The unifying idea behind every converter is the same: translate each of the tree-hierarchy and tile-geometry as-is, since each source format is already some spatial tree of pre-tiled, LoD'd content — so the converter just maps that tree onto a 3D Tiles HLOD tree, implicit (octree/quadtree) or explicit (arbitrary), and re-encodes node content into one shared output. The decode differs per format; the output is uniform.

It has since grown into an on-the-fly streaming middleware (packages/tile-server, the offline converters' live counterpart): point it at a <format> source URL and it serves a 3D Tiles tileset live, so any 3D-Tiles-compatible client — browser/JS viewers, CesiumJS or its native plugins (Unreal, Unity, Nvidia Omniverse, Open-3d-Engine), GIS software (QGIS, ESRI etc), anything that speaks the OGC standard — can consume any of these tiled formats without a pre-conversion step, with tile-hierarchy/content caching and prefetching tunable per use case (cache=none|hierarchy|all). A viewer (vite-served React app) based on CesiumJS and 3DTilesRendererJS is the reference client, and doubles as a bbox + geometric-error-aware crop/extract tool (/extract/*) for pulling a sub-region, with user-controlled Geometric Error target precision, of any of these formats back out as LAS/COPC/GLB/SPZ/SOG/PLY.

Towards a TiTiler for 3D

A TiTiler equivalent for 3D formats: middleware that reads cloud-native, internally tiled 3D formats and streams OGC 3D Tiles 1.1 on demand — transcribing the source octree/hierarchy into a 3D Tiles tree and converting raw node geometry to glTF/GLB, served over HTTP Range so nothing is re-encoded or re-sorted. Like TiTiler for COG: zero re-tiling, zero copy.

The intent: fully online, fetching only the required portions of the underlying format hierarchy to build the 3D Tiles JSON hierarchy, then — when GLB tiles are requested — fetching via range requests the corresponding {copc, stream-sog, lcc, potree, etc} contiguous memory block just to build the requested tile.

The end state is the same model generalised to every internally-tiled format (streamed-SOG chunk runs, LCC unit LOD runs, Potree octree-node byte ranges, …): a per-format "range adapter" mapping a requested 3D-Tiles key → the source byte range to fetch and transcode.

Supported Input Format

The format name below links to its canonical spec/source (multiple links where more than one canonical source exists); formats with no public spec (reverse-engineered/undocumented) link to nothing.

Output — 3D Tiles

Tiled point clouds → 3D Tiles

Generic tiled formats → 3D Tiles

Formats that carry (or wrap) a general node/mesh hierarchy rather than a point- or splat-specific one.

Bing Maps

Tiled Gaussian-splat sources → 3D Tiles

3D Tiles → 3D Tiles transcodes

The input is already 3D Tiles — these are tileset-level transforms (the live/streaming-flavored counterparts to 3d-tiles-tools). Served live by the /3dtiles-tools endpoint (packages/tile-server/3dtiles-tools-live.js): tileset JSON is rewritten once and cached; each tile is converted on demand (like /stream).

tool=implicit-to-explicit — read a tileset with implicitTiling (OCTREE/QUADTREE) + .subtree files, walk the availability bitstreams, and emit an explicit nested tree (derived boxes via the same octreeSubCube/cubeToBox core helpers as the octree converters). Per-tile .b3dm/.pnts content is converted to glb on the fly; .glb is proxied as-is. Works on local dirs and remote URLs.

tool=upgrade — legacy → 3D Tiles 1.1 with per-tile content conversion (packages/3dtiles-tools/upgrade.js):

• JSON-level: asset.version → 1.1, legacy content.url → uri (older 1.0/0.0 tilesets).
• b3dm → glb: a b3dm is a header + feature/batch tables + an embedded GLB — extracted by slicing to the GLB (zero-copy where possible).
• pnts → glb: parsed and re-encoded to a glTF POINTS GLB (native fast builder; POSITION / POSITION_QUANTIZED, RGBA/RGB/RGB565/CONSTANT_RGBA, RTC_CENTER → node translation).
• glTF 1.0 → 2.0: if the embedded GLB is version 1 (legacy pg2b3dm/older exporters), it is upgraded to glTF 2.0 via gltf-pipeline (processGlb) so Three.js/3DTRjs can load it (CesiumJS reads glTF 1.0 natively, Three.js does not).
• CESIUM_RTC baking: because we serve a plain GLB (bypassing each renderer's native b3dm/RTC handling), the b3dm's CESIUM_RTC.center (an ECEF offset) is folded into a wrapper node translation and the extension stripped. The center is pre-rotated by the inverse glTF up-axis (RX−90°: (x,y,z)→(x,z,−y)) so the renderer's Y-up→Z-up RX+90° restores the true ECEF position — otherwise the ~6378 km-magnitude center is itself rotated 90° and the geometry lands thousands of km away (correct bounding boxes, empty tiles). The small relative mesh vertices still get RX+90°, as in native b3dm.

i3dm/cmpt content and full PBR material rebuilds are deferred to 3d-tiles-tools (upgrade --targetVersion 1.1).

viewer.html's "⚙ Tools" mode groups a third operation, packages, alongside these two for UX — but it isn't a /3dtiles-tools?tool=… value at all: it routes to the separate /3dtiles-self-contained endpoint (a .3tz/.3dtiles package → a standard streamed 3D Tiles tileset — see "/3dtiles-self-contained — serve .3tz / .3dtiles packages in-place" in the architecture doc), not a tileset-level transcode. The grouping is "pick an operation to demo," not an architectural claim that packages lives under /3dtiles-tools.

Doable but low value (noted, not planned):

• Point-budget / downsample proxy — serve fewer/decimated tiles to weak clients. Marginal: a capable renderer (CesiumJS / 3DTilesRendererJS) already loads only what its SSE budget needs.
• Mesh → points — emit only vertices of a mesh tileset. Niche (loses the surface; render-time can approximate), listed for completeness.

For full offline pipelines (merge, mergeJson, upgrade, b3dmToGlb/pnts/i3dm/cmpt → glTF), use 3d-tiles-tools — the canonical CesiumGS toolbox.