Awesome

<p align="center"> GS-IR: 3D Gaussian Splatting for Inverse Rendering </p>

<p align="center"> Zhihao Liang, Qi Zhang, Ying Feng, Ying Shan, Kui Jia</p>

<p align="center">Project Page | ArXiv | Paper</p>

Introduction

We present GS-IR that models a scene as a set of 3D Gaussians to achieve physically-based rendering and state-ofthe-art decomposition results for both objects and scenes.

Welcome to our new work Analytic-Splatting. We achieve anti-aliasing and excellent detail fidelity through analytical integral approximation. Analytic-Splatting was accepted by ECCV 2024!

Installation

create the basic environment

conda env create --file environment.yml
conda activate gsir

pip install kornia

install some extensions

cd gs-ir && python setup.py develop && cd ..

cd submodules
git clone https://github.com/NVlabs/nvdiffrast
pip install ./nvdiffrast

pip install ./simple-knn
pip install ./diff-gaussian-rasterization # or cd ./diff-gaussian-rasterization && python setup.py develop && cd ../..

Dataset

We evaluate our method on TensoIR-Synthetic and Mip-NeRF 360 datasets. And please visit here for the environment maps. Please refer to the TensoIR for more details about TensoIR-Synthetic and Environment map.

Running

TensoIR-Synthetic

Take the lego case as an example.

Stage1 (Initial Stage)

python train.py \
-m outputs/lego/ \
-s datasets/TensoIR/lego/ \
--iterations 30000 \
--eval

Baking

python baking.py \
-m outputs/lego/ \
--checkpoint outputs/lego/chkpnt30000.pth \
--bound 1.5 \
--occlu_res 128 \
--occlusion 0.25

Stage2 (Decomposition Stage)

python train.py \
-m outputs/lego/ \
-s datasets/TensoIR/lego/ \
--start_checkpoint outputs/lego/chkpnt30000.pth \
--iterations 35000 \
--eval \
--gamma \
--indirect

set --gamma to enable linear_to_sRGB will cause better relighting results but worse novel view synthesis results set --indirect to enable indirect illumination modelling

Evaluation (Novel View Synthesis)

python render.py \
-m outputs/lego \
-s datasets/TensoIR/lego/ \
--checkpoint outputs/lego/chkpnt35000.pth \
--eval \
--skip_train \
--pbr \
--gamma \
--indirect

Evaluation (Normal)

python normal_eval.py \
--gt_dir datasets/TensoIR/lego/ \
--output_dir outputs/lego/test/ours_None

Evaluation (Albedo)

python render.py \
-m outputs/lego \
-s datasets/TensoIR/lego/ \
--checkpoint outputs/lego/chkpnt35000.pth \
--eval \
--skip_train \
--brdf_eval

Relighting

python relight.py \
-m outputs/lego \
-s datasets/TensoIR/lego/ \
--checkpoint outputs/lego/chkpnt35000.pth \
--hdri datasets/TensoIR/Environment_Maps/high_res_envmaps_2k/bridge.hdr \
--eval \
--gamma

set --gamma to enable linear_to_sRGB will cause better relighting results but worse novel view synthesis results

Relighting Evaluation

python relight_eval.py \
--output_dir outputs/lego/test/ours_None/relight/ \
--gt_dir datasets/TensoIR/lego/

Mip-NeRF 360

Take the bicycle case as an example.

Stage1 (Initial Stage)

python train.py \
-m outputs/bicycle/ \
-s datasets/nerf_real_360/bicycle/ \
--iterations 30000 \
-i images_4 \
-r 1 \
--eval

-i images_4 for outdoor scenes and -i images_2 for indoor scenes -r 1 for resolution scaling (not rescale)

Baking

python baking.py \
-m outputs/bicycle/ \
--checkpoint outputs/bicycle/chkpnt30000.pth \
--bound 16.0 \
--occlu_res 256 \
--occlusion 0.4

Stage2 (Decomposition Stage)

python train.py \
-m outputs/bicycle \
-s datasets/nerf_real_360/bicycle/ \
--start_checkpoint outputs/bicycle/chkpnt30000.pth \
--iterations 40000 \
-i images_4 \
-r 1 \
--eval \
--metallic \
--indirect

set --metallic choose to reconstruct metallicness set --gamma to enable linear_to_sRGB will cause better relighting results but worse novel view synthesis results set --indirect to enable indirect illumination modelling

Evaluation

python render.py \
-m outputs/bicycle \
-s datasets/nerf_real_360/bicycle/ \
--checkpoint outputs/bicycle/chkpnt40000.pth \
-i images_4 \
-r 1 \
--eval \
--skip_train \
--pbr \
--metallic \
--indirect

set --gamma to enable linear_to_sRGB will cause better relighting results but worse novel view synthesis results

Relighting

python relight.py \
-m outputs/bicycle \
-s datasets/nerf_real_360/bicycle/ \
--checkpoint outputs/bicycle/chkpnt40000.pth \
--hdri datasets/TensoIR/Environment_Maps/high_res_envmaps_2k/bridge.hdr \
--eval \
--gamma

set --gamma to enable linear_to_sRGB will cause better relighting results but worse novel view synthesis results

Demo Implementation

In addition, you can conduct the following script and get the same results of demo in project page:

# Stay point light and move camera
python shadow_map.py -m output/garden-linear/ \
-s dataset/nerf_data/nerf_real_360/garden/ \
--checkpoint output/garden-linear/chkpnt35000.pth \
--frames 480 \
--fps 60 \
--start 158 \
--end 184 \
--linear \
--loop

# Stay camera and move point light
python light_move.py -m output/garden-linear/ \
-s dataset/nerf_data/nerf_real_360/garden/ \
--checkpoint output/garden-linear/chkpnt35000.pth \
--frames 240 \
--fps 30 \
--start 158 \
--end 184 \
--loop --\
linear

Acknowledge

• gaussian-splatting
• nvdiffrast
• nvdiffrec

Citation

If you find this work useful in your research, please cite:

@article{liang2023gs,
  title={Gs-ir: 3d gaussian splatting for inverse rendering},
  author={Liang, Zhihao and Zhang, Qi and Feng, Ying and Shan, Ying and Jia, Kui},
  journal={arXiv preprint arXiv:2311.16473},
  year={2023}
}