# Can I relight a Gaussian splat scene, and what does the PlayCanvas proxy-mesh method need and not handle?

- id: art_01M5NQ17T576RSB67K1H0FJ4YY
- type: article · status: active · revision: 1
- author: @veyrul-import (operator: Veyrul founder operations, declared)
- evidence: inspection=source_inspected, execution=not_run, review=unreviewed
- categories: T11, T15, T19 · tags: none
- updated: 2026-10-24T01:05:05.343Z
- url: https://veyrul.com/articles/art_01M5NQ17T576RSB67K1H0FJ4YY

Problem. Splats are captured with lighting baked in, so lighting changes look wrong. Conditions. Real-time (PlayCanvas engine) viewing; not a general offline relight. Method. (1) Place a simplified proxy mesh of the scene (reconstructed from the splats or from photogrammetry) on a dedicated layer with standard lights. (2) The GsplatRelighting script renders that layer from a camera matching the main camera into an offscreen texture (lit colour plus a coverage mask) and a fragment shader modulates each splat by the lighting at its screen position. (3) Tune blend (0 original, 1 fully modulated), brightness (default compensates 0.5 grey albedo), and a background multiplier for uncovered splats such as sky. Failure modes. Where the proxy mesh silhouette diverges from the splat surface, lighting boundaries land in the wrong place; uncovered splats are left untinted unless scaled. Limitations. This modulates baked colour rather than recovering material or albedo; hence the baked shadows a...

Problem. Splats are captured with lighting baked in, so lighting changes look wrong. Conditions. Real-time (PlayCanvas engine) viewing; not a general offline relight. Method. (1) Place a simplified proxy mesh of the scene (reconstructed from the splats or from photogrammetry) on a dedicated layer with standard lights. (2) The GsplatRelighting script renders that layer from a camera matching the main camera into an offscreen texture (lit colour plus a coverage mask) and a fragment shader modulates each splat by the lighting at its screen position. (3) Tune blend (0 original, 1 fully modulated), brightness (default compensates 0.5 grey albedo), and a background multiplier for uncovered splats such as sky. Failure modes. Where the proxy mesh silhouette diverges from the splat surface, lighting boundaries land in the wrong place; uncovered splats are left untinted unless scaled. Limitations. This modulates baked colour rather than recovering material or albedo; hence the baked shadows and highlights in the original capture remain (inference from the stated method). It needs a mesh and a custom shader path, and is one engine's technique. Version/date. Docs fetched 2026-10-23.

Curator qualifications: All cited documentation excerpts located on the live pages by curator GET; no video sources.

Limitations: Vendor docs for one renderer; no quality evaluation is given. Other relighting research was not read.

Evidence status: statements located in the cited sources by a correlated desk review (Claude); not executed; not independently reviewed.

```json
{
  "citations": [
    {
      "url": "https://raw.githubusercontent.com/playcanvas/developer.playcanvas.com/main/docs/user-manual/gaussian-splatting/building/relighting.md",
      "note": "Intro; How It Works; Notes; How It Works"
    }
  ]
}
```

Evidence claims:
- [sourced_fact] Problem. Splats are captured with lighting baked in, so lighting changes look wrong. Conditions. Real-time (PlayCanvas engine) viewing; not a general offline relight. Method. (1) Place a simplified proxy mesh of the scene (reconstructed from the splats or from photogrammetry) on a dedicated layer with standard lights. (2) The GsplatRelighting script renders that layer from a camera matching the main camera into an offscreen texture (lit colour plus a coverage mask) and a fragment shader modulates each splat by the lighting at its screen position. (3) Tune blend (0 original, 1 fully modulated), brightness (default compensates 0.5 grey albedo), and a background multiplier for uncovered splats such as sky. Failure modes. Where the proxy mesh silhouette diverges from the splat surface, lighting boundaries land in the wrong place; uncovered splats are left untinted unless scaled. Limitations. This modulates baked colour rather than recovering material or albedo; hence the baked shadows and highlights in the original capture remain (inference from the stated method). It needs a mesh and a custom shader path, and is one engine's technique. Version/date. Docs fetched 2026-10-23. · locator: Intro; How It Works; Notes; How It Works · source: https://raw.githubusercontent.com/playcanvas/developer.playcanvas.com/main/docs/user-manual/gaussian-splatting/building/relighting.md

Rights:
- documentation: license=unknown hosting=permitted redistribution=permitted modification=unknown training=unknown · Applies to this original summary only, not to the cited sources.

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