Cesium 3D Tiles geospatial streaming

Dawn Engine Cesium 3D Tiles streams global-scale geospatial content (terrain, photogrammetry, BIM, point clouds, Gaussian splats, voxels) into the Atom renderer using cesium-native and the 3D Tiles standard. It provides WGS84 georeference, camera-driven LOD, Cesium ion and self-hosted data sources, raster overlays, globe anchors, origin shift, and fly navigation—expressed as O3DE components and EBuses, and integrated with Dawn’s LargeWorld double-precision coordinates.

Maturity: Experimental / shipped in-engine (Cesium3DTiles Gem, v0.2.0). Desktop platforms: Windows, Linux, Mac. Geospatial scenes require double-precision rendering (LargeWorld / RenderOriginService); the Gem can enable LargeWorld on activate. Mobile (Android / iOS) is not in the support matrix.

Difference from O3DE: the historical external Cesium for O3DE community Gem is no longer actively maintained. Dawn Engine ships Cesium built into the engine, continuously maintained, and integrated with LargeWorld so globe-scale tilesets work with the rest of the Dawn large-world stack.

It does not replace PolyTerrain or World Streaming: Cesium owns globe-scale 3D Tiles LOD; Terrain and World Streaming remain available and can coexist via optional bridges.

What problem it solves

Digital twins, simulation training, and GIS visualization need real-world context at planetary scale. Cesium3DTiles provides:

• End-to-end streaming from Cesium ion, URL, or local tileset.json into Atom;
• Accurate LLH / ECEF / engine-local transforms on a WGS84 (or custom) ellipsoid;
• Imagery and vector overlays draped on tileset geometry;
• Globe-anchored entities, fly camera, origin shift for large-world precision;
• Optional PhysX tile colliders, metadata picking, credits attribution, and editor tooling.

With the Gem disabled, Terrain / WorldStreaming / LargeWorld behavior is unchanged.

How it works

ion / URL / local tileset.json
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cesium-native (tile selection · load · glTF)
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Atom MeshFeatureProcessor (+ optional PhysX)
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LargeWorld RenderOrigin (float relative to camera)
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ScriptCanvas / EBus (anchors, fly-to, metadata)

Key ideas:

1. Georeference maps LLH/ECEF to the level’s local frame (default: cartographic origin → engine (0,0,0), +X East, +Y North, +Z Up).
2. Tilesets refine by screen-space error (SSE) from aggregated camera frustums.
3. Raster overlays are separate LOD streams textured onto tile meshes (up to four material slots on the default material).
4. Origin shift keeps the render origin near the camera so single-precision GPU transforms stay stable at global scale.

Layout under Gems/Cesium3DTiles/:

Quick start (summary)

1. Enable Cesium3DTiles (and PhysX if you need tile colliders).
2. Set CESIUM_ION_TOKEN or open Tools → Cesium Settings.
3. Build a minimal hierarchy: Georeference → Tileset (ion 1) + Ion Raster Overlay (ion 2) → SunSky + Credits → Camera with Fly Controller + Origin Shift.

For the full walkthrough and verification checklist, see Getting started.

Handbook chapters

Glossary

Limits and related capabilities

You can rely on:

• ion / URL / local tileset streaming with camera-driven LOD;
• Georeference, Globe Anchor, Origin Shift, Fly Controller / Fly-To, geographic sub-levels;
• Multiple raster overlay providers and credit display;
• Optional PhysX colliders; Gaussian splat and voxel paths when content supports them;
• Editor Settings, ion asset browser, Quick Add, and token troubleshooter.

Do not assume:

• Mobile runtime support;
• That Terrain or World Streaming cells are replaced (they coexist; bridges are opt-in);
• That empty ion tokens or wrong asset permissions will load silently—check network and Troubleshoot Token;
• That PIE without Unload tiles in play mode stays memory-safe with large tilesets;
• That occlusion culling is production-ready (experimental, off by default).

Next steps

• Getting started — shortest path to a working globe.
• Double-precision rendering — required foundation for globe-scale precision.
• World Streaming — stream local Prefab cells beside Cesium globe content.
• Navigation3D — volumetric air navigation over Cesium terrain.