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Semantic Gaussians: Open-Vocabulary Scene Understanding with 3D Gaussian Splatting

This repository is the official implemetation of the paper "Semantic Gaussians: Open-Vocabulary Scene Understanding with 3D Gaussian Splatting".

Abstract

Open-vocabulary 3D scene understanding presents a significant challenge in computer vision, with wide-ranging applications in embodied agents and augmented reality systems. Previous approaches have adopted Neural Radiance Fields (NeRFs) to analyze 3D scenes. In this paper, we introduce Semantic Gaussians, a novel open-vocabulary scene understanding approach based on 3D Gaussian Splatting. Our key idea is distilling pretrained 2D semantics into 3D Gaussians. We design a versatile projection approach that maps various 2D semantic features from pretrained image encoders into a novel semantic component of 3D Gaussians, without the additional training required by NeRFs. We further build a 3D semantic network that directly predicts the semantic component from raw 3D Gaussians for fast inference. We explore several applications of Semantic Gaussians: semantic segmentation on ScanNet-20, where our approach attains a 9.3% mIoU and 6.5% mAcc improvement over prior open-vocabulary scene understanding counterparts; object part segmentation, scene editing, and spatial-temporal segmentation with better qualitative results over 2D and 3D baselines, highlighting its versatility and effectiveness on supporting diverse downstream tasks.

Prerequisites

This code has been tested on Ubuntu 22.04 and NVIDIA RTX 4090. We recommend to use Linux and an NVIDIA GPU with ≥ 16GB VRAM. This repository may support Windows machines but it was not evaluated. It cannot support MacOS system as it requires CUDA.

Install

1. Clone our repository (remember to add the --recursive argument to clone submodules).

   git clone https://github.com/sharinka0715/semantic-gaussians --recursive
   cd semantic-gaussians
   

2. Create individual virtual environment (or use existing environments with CUDA Development kit and corresponding version of PyTorch).

   conda env create -f environment.yaml
   conda activate sega
   

3. Install additional dependencies with pip as many of them need to be compiled.

   pip install -r requirements.txt
   

4. Compile and install MinkowskiEngine through anaconda, recommending to install through official instructions.

   # Here is an example only for Anaconda, CUDA 11.x
   conda install openblas-devel -c anaconda
   pip install git+https://github.com/NVIDIA/MinkowskiEngine -v --no-deps --install-option="--blas_include_dirs=${CONDA_PREFIX}/include" --install-option="--blas=openblas"
   

Prepare Dataset and Pretrained 2D Models

Data structure

This repository supports three formats of dataset for 3D Gaussians Splatting:

• Blender format

  scene_name
  |-- images/
  |-- points3d.ply
  |-- transforms_train.json
  

• COLMAP format

  scene_name
  |-- images/
  |-- sparse/
  |   |-- 0
  |   |   |-- cameras.bin
  |   |   |-- points3D.bin
  

• ScanNet format

  scene_name
  |-- color/
  |-- intrnsic/
  |-- pose/
  |-- points3d.ply
  

Blender and COLMAP formats are originally supported by 3D Gaussian Splatting and many NeRF-based works. You can easily prepare your dataset as these two format.

The ScanNet dataset can be extracted by tools/scannet_sens_reader.py. You can also use tools/unzip_lable_filt.py to extract ground truth semantic labels in ScanNet-20 dataset.

# An example used for experiments in paper
python tools/scannet_sens/reader.py --input_path /PATH/TO/YOUR/scene0000_00 --output_path /PATH/TO/YOUR/OUTPUT/scene0000_00

Datasets Used in Paper

Pretrained 2D Vision-Language Models

You should put these downloaded pretrained checkpoints under the ./weight/ folder, or you can modify the saving path in YAML configs.

Usage

This repository has 4 entries to start a program. Every entry has its corresponding config YAML file. You only need to run python xxx.py, all configs are in YAML files.

• train.py: Train normal RGB gaussians. Code mainly from 3D Gaussian Splatting official repository.

  config: config/official_train.yaml.

  This will output 3D Gaussians under output/ folder.

• fusion.py: Apply 2D versatile projection.

  config: config/fusion_scannet.yaml.

  This will output fused features under config.fusion.out_dir

• distill.py: Train 3D semantic network.

  config: config/distill_scannet.yaml.

  This will output 3D semantic network checkpoints in results_distlll/ folder.

• eval_segmentation.py: Evaluate the semantic segmentation performance on ScanNet dataset.

  config: config/eval.yaml.

  This will print the evaluation results on the screen.

• view_viser.py: View the semantic Gaussians. Need 2D projected results (*.pt) and original RGB Gaussians.

  config: config/view_scannet.yaml.

  This will open a web service supported by viser.

Acknowledgements

We appreciate the works below as this repository is heavily based on them:

[SIGGRAPH 2023] 3D Gaussian Splatting for Real-Time Radiance Field Rendering

[CVPR 2023] OpenScene: 3D Scene Understanding with Open Vocabularies

[ECCV 2022] OpenSeg: Scaling Open-Vocabulary Image Segmentation with Image-Level Labels

[Cheems Seminar] Grounded Segment Anything: From Objects to Parts

News

• [2024.07] We fix some dependency problems in our code. Add LSeg modules.

• [2024.05] We release our initial version of implemetation.

Citation

@misc{guo2024semantic,
    title={Semantic Gaussians: Open-Vocabulary Scene Understanding with 3D Gaussian Splatting}, 
    author={Jun Guo and Xiaojian Ma and Yue Fan and Huaping Liu and Qing Li},
    year={2024},
    eprint={2403.15624},
    archivePrefix={arXiv},
    primaryClass={cs.CV}
  }