Google 3D Tiles with R3F and ENU Coordinates

When to Use This Skill

• Integrating Google Maps Photorealistic 3D Tiles or Google Earth 3D Tiles API into a web app
• Building a Three.js or React Three Fiber (R3F) scene that displays real-world 3D terrain/buildings
• Correcting 座標系 (coordinate systems): converting ECEF (Earth-Centered, Earth-Fixed) to ENU (East-North-Up) so the map is flat and Y-up for gameplay, camera, or audio
• Placing objects (camera, vehicles, audio sources) in the same coordinate system as the tiles

Quick Overview

1. Tiles: Google 3D Tiles are served in ECEF. Use 3d-tiles-renderer with TilesRenderer (R3F) and GoogleCloudAuthPlugin (API key).
2. R3F: Render tiles inside a <Canvas>; wrap TilesRenderer in a transformer group that applies an ECEF→ENU matrix so the scene is local and Y-up.
3. Consistency: Use a single origin (e.g. city center). Convert all lat/lng/alt to ENU with that origin so camera, physics, and tiles share the same 座標系.

Stack and Packages

• three + @react-three/fiber (R3F)
• 3d-tiles-renderer (provides TilesRenderer, TilesPlugin, WGS84_ELLIPSOID, GoogleCloudAuthPlugin, GLTFExtensionsPlugin)
• Optional: three/examples/jsm/loaders/DRACOLoader for compressed tiles

Google Tiles root URL: https://tile.googleapis.com/v1/3dtiles/root.json. API key required (Google Cloud Maps API / 3D Tiles).

Coordinate Correction (ECEF → ENU)

• ECEF: Earth-centered, Cartesian. Tiles from Google are in ECEF.
• ENU: East-North-Up at a chosen origin. X=east, Y=north, Z=up (then remap to Three.js Y-up: X=east, Y=up, Z=-north so north is -Z).

Steps:

1. Get ENU→ECEF at origin (lat, lng) using WGS84 ellipsoid (e.g. WGS84_ELLIPSOID.getEastNorthUpFrame from 3d-tiles-renderer/three), then invert to get ECEF→ENU.
2. Apply a Y-up remap so Three.js convention is X=east, Y=up, Z=-north (geographic north = -Z).
3. Set this matrix on the parent group of the tiles (e.g. the group that wraps TilesRenderer), and set matrixAutoUpdate = false.

All other scene objects (camera, entities) should use the same origin and the same ENU↔lat/lng conversion (e.g. latLngAltToENU / enuToLatLngAlt) so positions align with the transformed tiles.

Checklist

• R3F Canvas with appropriate camera near/far and optional logarithmicDepthBuffer for large scenes
• Tiles: TilesRenderer wrapped in a group; apply ECEF→ENU+Y-up matrix to that group once on mount
• Auth: TilesPlugin with GoogleCloudAuthPlugin and apiToken (API key)
• Optional: GLTFExtensionsPlugin + DRACOLoader for Draco tiles
• Single origin (e.g. ORIGIN_LAT, ORIGIN_LNG); all lat/lng/alt converted to ENU relative to that origin
• Geo utils: latLngAltToENU and enuToLatLngAlt use the same Y-up remap (Z = -north) as the tiles transform

Additional Resources

• reference.md — Concepts and 座標系 summary; all code lives in examples/ so the skill is project-agnostic.
• examples/ — Copy-paste files: config, geo-utils, ECEF→ENU matrix + TilesTransformer, TilesScene, page snippet. See examples/README.md for copy-to-path mapping.