NICER-SLAM: Neural Implicit Scene Encoding for RGB SLAM

Zihan Zhu* · Songyou Peng* · Viktor Larsson · Zhaopeng Cui · Martin R. Oswald

Andreas Geiger · Marc Pollefeys

(* Equal Contribution)

3DV 2024 (Best Paper Honorable Mention)

Paper | Video | Project Page

NICER-SLAM produces accurate dense geometry and camera tracking without the need of depth sensor input.

(The black / red lines are the ground truth / predicted camera trajectory)

Table of Contents

1. Installation
2. Visualization
3. Demo
4. Run
5. Evaluation
6. Acknowledgement
7. Citation
8. Contact

Installation

First you have to make sure that you have all dependencies in place. The simplest way to do so, is to use anaconda.

You can create an anaconda environment called nicer-slam.

conda env create -f env_yamls/nicer-slam.yaml
conda activate nicer-slam

Visualizing NICER-SLAM Results

We provide the results of NICER-SLAM ready for download. You can run our interactive visualizer as following.

Self-captured Outdoor Dataset

To visualize our results on the Self-captured Outdoor Dataset:

bash scripts/download_vis_sco.sh
# Choose one of the following scenes
OUTPUT_FOLDER=exps/azure_2/2024_03_11_22_57_38sample_vis
OUTPUT_FOLDER=exps/azure_3/2024_03_11_22_57_38sample_vis
python visualizer.py --output $OUTPUT_FOLDER

You can find more results of NICER-SLAM here.

7-Scenes

bash scripts/download_vis_7scenes_office.sh
OUTPUT_FOLDER=exps/7scenes_4/2024_02_27_15_05_29sample_vis
python visualizer.py --output $OUTPUT_FOLDER

Replica

bash scripts/download_vis_replica_room2.sh
OUTPUT_FOLDER=exps/replica_3/2024_02_27_00_12_45sample_vis
python visualizer.py --output $OUTPUT_FOLDER

Interactive Visualizer Usage

The black trajectory indicates the ground truth trajectory, and the red is trajectory of NICER-SLAM.

• Press Ctrl+0 for grey mesh rendering.
• Press Ctrl+1 for textured mesh rendering.
• Press Ctrl+9 for normal rendering.
• Press L to turn off/on lighting.

Command Line Arguments

• --output $OUTPUT_FOLDER output folder
• --save_rendering save rendering video to vis.mp4 in the output folder
• --render_every_frame screen recording speed and frame rate are syncd, one frame in video corresponds to one frame in input
• --no_gt_traj do not show ground truth trajectory

Demo

Here you can run NICER-SLAM yourself on two short sequences with 200 frames.

First, download the demo data as below and the data is saved into the ./Datasets/processed/Demo folder.

bash scripts/download_demo.sh

Next, run NICER-SLAM. It takes about half an hour with ~24G GPU memory.

For short sequence from Self-captured Outdoor Dataset.

cd code
python training/exp_runner.py --conf confs/runconf_demo_1.conf

For short sequence from Replica Dataset.

cd code
python training/exp_runner.py --conf confs/runconf_demo_2.conf

Finally, run the following command to visualize.

# here is just an example, change to your output folder
OUTPUT_FOLDER=exps/demo_1/2024_03_16_16_39_08demo
python code/evaluation/eval_cam.py --output $OUTPUT_FOLDER
python visualizer.py --output $OUTPUT_FOLDER

NOTE: This is for demonstration only, its configuration/performance may be different from our paper.

Third Party

Install third-party repositories for monocular depth/normal estimation and optical flow extraction.

mkdir 3rdparty
cd 3rdparty
git clone https://github.com/EPFL-VILAB/omnidata.git
cd omnidata/omnidata_tools/torch
mkdir -p pretrained_models && cd pretrained_models
wget 'https://zenodo.org/records/10447888/files/omnidata_dpt_depth_v2.ckpt'
wget 'https://zenodo.org/records/10447888/files/omnidata_dpt_normal_v2.ckpt'
cd ..
cd ../../../
git clone https://github.com/haofeixu/gmflow.git
cd gmflow

Download GMFlow's pretrained models from https://drive.google.com/file/d/1d5C5cgHIxWGsFR1vYs5XrQbbUiZl9TX2/view?usp=sharing to the gmflow folder. Then unzip it.

unzip pretrained.zip
cd ../../

Install the environments for the third-party repositories.

conda env create -f env_yamls/gmflow.yaml
conda env create -f env_yamls/omnidata.yaml

Run

Replica Dataset

Download the data as below and the data is saved into the ./Datasets/orig/Replica folder. Note that the Replica data is generated by the authors of iMAP, so please cite iMAP if you use the data.

bash scripts/download_replica.sh

Run the following command to preprocess the data. This includes converting the camera pose to VolSDF format, extracting monocular depth/normal estimation and optical flow. The processed data is saved into the ./Datasets/processed/Replica folder. NOTE that the npy file for depth/normal/flow is compressed with lzma to save storage.

python preprocess/replica_2_volsdf.py

Then you can run NICER-SLAM:

cd code
python training/exp_runner.py --conf confs/replica/runconf_replica_2.conf

7-Scenes Dataset

Download the data as below and the data is saved into the ./Datasets/orig/7Scenes folder.

bash scripts/download_7scenes.sh

The 7-Scenes dataset does not provide meshes. We provide the following code to do TSDF-Fusion on the gt pose and depth image to get the mesh.

python preprocess/get_mesh_7scenes.py

Run the following command to preprocess the data. This includes converting the camera pose to VolSDF format, extracting monocular depth/normal estimation and optical flow. The processed data is saved into the ./Datasets/processed/7Scenes folder.

python preprocess/7scenes_2_volsdf.py

Then you can run NICER-SLAM:

cd code
python training/exp_runner.py --conf confs/7scenes/runconf_7scenes_2.conf

Self-captured Outdoor Dataset

Download the data as below and the data is saved into the ./Datasets/orig/Azure folder.

bash scripts/download_azure.sh

Run the following command to preprocess the data. This includes converting the camera pose to VolSDF format, extracting monocular depth/normal estimation and optical flow. The processed data is saved into the ./Datasets/processed/Azure folder.

python preprocess/azure_2_volsdf.py

Then you can run NICER-SLAM:

cd code
python training/exp_runner.py --conf confs/azure/runconf_azure_2.conf

NOTE: Please ensure your GPU has over 30GB of memory to avoid surpassing the GPU memory limit. Reducing the batch size can help lessen memory consumption, though it will require more iterations to achieve comparable performance.

Evaluation

Average Trajectory Error

To evaluate the average trajectory error. Run the command below with the corresponding output folder name:

# assign any output_folder you like, here is just an example
OUTPUT_FOLDER=exps/replica_4/2024_03_01_00_07_16code_release
python code/evaluation/eval_cam.py --output $OUTPUT_FOLDER

NOTE: For Self-captured Outdoor Dataset, the error is in COLMAP's metric system, not in cm.

Reconstruction Error

Unlike NICE-SLAM that evaluates on culled mesh, in NICER-SLAM we directly evaluates on the original mesh to showcase the extrapolation ability of our reconstruction.

# assign any output_folder you like, here is just an example
OUTPUT_FOLDER=exps/replica_4/2024_03_01_00_07_16code_release
python code/evaluation/eval_rec.py --output $OUTPUT_FOLDER

Rendering Evaluation

Interpolation

Evaluate the rendering on non-keyframes of input sequences, in default it selects the indexs range(2, n_imgs, 100).

# assign any run, here is just an example
TIMESTAMP=2024_03_01_00_07_16code_release
CONF=../exps/replica_4/2024_03_01_00_07_16code_release/runconf.conf
cd code
python evaluation/eval_rendering.py --conf $CONF --checkpoint latest --is_continue --timestamp $TIMESTAMP --eval_method interpolate

Extrapolation

To evaluate the method's ability to rendering on extrapolated views. We made an extrapolation rendering evaluation set on the Replica dataset using the Replica Renderer. It should be downloaded while downloading the replica dataset and saved into the folder Datasets/orig/Replica_eval_ext. Run the following command to preprocess it to VolSDF coordinate system.

python preprocess/replica_eval_2_volsdf.py

Now we are ready to evaluate.

# assign any run, here is just an example
TIMESTAMP=2024_03_01_00_07_16code_release
CONF=../exps/replica_4/2024_03_01_00_07_16code_release/runconf.conf
cd code
python evaluation/eval_rendering.py --conf $CONF --checkpoint latest --is_continue --timestamp $TIMESTAMP --eval_method extrapolate

Acknowledgement

We adapted some codes from some awesome repositories including convolutional_occupancy_networks, nerf-pytorch, lietorch, BARF, VolSDF, MonoSDF, MiDaS and DIST-Renderer. Thanks for making codes public available.

Citation

If you find our code or paper useful, please cite

@inproceedings{Zhu2024NICER,
  author={Zhu, Zihan and Peng, Songyou and Larsson, Viktor and Cui, Zhaopeng and Oswald, Martin R and Geiger, Andreas and Pollefeys, Marc},
  title     = {NICER-SLAM: Neural Implicit Scene Encoding for RGB SLAM},
  booktitle = {International Conference on 3D Vision (3DV)},
  month     = {March},
  year      = {2024},
}

Contact

Contact Zihan Zhu and Songyou Peng for questions, comments and reporting bugs.