GBake

GBake bakes light probes from 3D Gaussian Splat models. Given a trained Gaussian Splat scene (as a .ply file), it places a grid of probes throughout the scene and renders a cubemap from each probe position. The output is a set of cross-layout cubemap PNG images and a JSON file mapping each probe's 3D position to its cubemap — ready to be consumed by a game engine for real-time lighting.

Installation

python -m venv .venv
source .venv/bin/activate
pip install -r requirements.txt

GBake has two rendering backends. The default (bake_raytrace.py) uses 3D-GRT (threedgrut). Install it separately and place this repo alongside it so that the assets symlink (../3dgrut/assets) resolves correctly:

parent_dir/
├── 3dgrut/       # install 3D-GRT here
└── gbake/        # this repo

The alternative backend (bake_splat.py) uses gsplat, which is included in requirements.txt.

Usage

Default: threedgrut backend

python bake_raytrace.py --ply_file path/to/scene.ply --n_per_axis 5 --cubemap_resolution 800

Argument	Default	Description
--ply_file	hotdog/hotdog_ns.ply	Path to the input .ply file
--n_per_axis	5	Grid density per axis (5 → 125 probes)
--cubemap_resolution / --res	800	Resolution of each cubemap face in pixels

Alternative: gsplat backend

python bake_splat.py --ply_file path/to/scene.ply --output_dir path/to/output --n_per_axis 10

Argument	Default	Description
--ply_file	(required)	Path to the input .ply file
--output_dir	(required)	Directory to write cubemaps and JSON
--n_per_axis	10	Grid density per axis
--overlap	0	Face overlap in degrees

Getting a PLY file

GBake expects a trained Gaussian Splat model exported as a .ply. The primary workflow is to train with 3D-GRT and use its exported PLY directly with bake_raytrace.py. Alternatively, train with NeRF Studio (splatfacto) and export with ns-export gaussian-splat --ply-color-mode rgb for use with bake_splat.py.

Output format

Each probe produces one cubemap image saved as a cross-layout PNG (4 faces wide × 3 faces tall):

      [Top   ]
[Left][Front ][Right][Back]
      [Bottom]

All probe positions and cubemap paths are written to a *_probe_data.json file in the output directory:

{
  "probes": [
    {
      "index": 0,
      "position": [x, y, z],
      "cubemap": "Assets/ProbeData/Cubemaps/scene_0.png"
    }
  ]
}