Neural Implicit Surface Evolution

Tiago Novello [1], Vinícius da Silva [2], Guilherme Schardong [3], Luiz Schirmer [4], Hélio Lopes [2], Luiz Velho [1]
[1] Institute for Pure and Applied Mathematics (IMPA), [2] Pontifical Catholic University of Rio de Janeiro (PUC-Rio), [3] University of Coimbra (UC) [4] University of the Sinos Valley (UNISINOS)

This is the official implementation of "Neural Implicit Surface Evolution", to appear at the Proceedings of ICCV 2023, published on arXiv.

Getting started

Prerequisites

1. Mamba (Miniforge) on Windows, alternativelly you can use PyEnv and PyEnv-VirtualEnv on UNIX based/like systems
2. Git
3. (Optional) MeshLab
4. (Optional) NVIDIA Kaolin

If using Linux, or macOS, these programs should be available through the package manager, or Homebrew.

Code organization

The common code is contained in the nise package. Inside the respective folder, there are the following files:

• dataset.py - contains the sampling and data classes
• diff_operators.py - implementation of differential operators (gradient, hessian, jacobian, curvatures)
• loss.py - contains loss functions for different experimental settings
• meshing.py - mesh creation through marching cubes
• model.py - networks and layers implementations
• util.py - miscelaneous functions and utilities

The main training and reconstruction scripts are in the repository's root folder:

• meancurvature-train.py - train a smoothing/sharpening of a single neural implicit surface (see Sec 6.2 in the paper)
• morph-train.py - train an interpolation between two neural implicit surfaces (see Sec 6.3 in the paper)
• reconstruct.py - given a trained model (pth) reconstructs the mesh using marching cubes at values t given by the user
• vectorfield-train.py - train a neural-based deformation of a neural implicit surface (see Sec 6.1 in the paper)

Additionally, under the experiment_scripts folder, there are more scripts with experiments and other auxiliary code that is generally independent of the main code.

Note that these scripts were written them some time ago and may not run as smoothly as expected. We are working to update them.

• discrete_smoothing.py - experiments with discrete smoothing methods (laplacian, cotangent, etc.)
• enlarge_networks.py - studying the effects of increasing network width in the training results (see Sec. 4.4 of the supplementary material)
• lipschitz_exp.py - experiments with lipschitz regularization
• mean_curvature_scale.py - experiments with different values for the mean curvature equation scale parameter (see Sec. 4.2 of the supplementary material)
• point_sample_proportions.py - experiments with the proportions of points drawn from the surface, off-surface and along time (see Sec. 4.3 of the supplementary material)
• training_time_intervals.py - studies with varying time-intervals for training (see Sec. 4.1 of the supplementary material)

Setup and sample run

1. Open a terminal (or Git Bash if using Windows)
2. Clone this repository: git clone git@github.com:dsilvavinicius/nise.git
3. Enter project folder: cd nise
4. Setup project dependencies via Mamba

mamba env create -f environment.yml
conda activate nise
pip install -e .

or, if using pyenv (with pyenv-virtualenv):

pyenv virtualenv 3.9.9 nise
pyenv local nise
pip install -r requirements.txt
pip install -e .

5. Download the pretrained neural implicit objects into the ni folder in the repository
6. Download the meshes into the data folder in the repository
7. Run the desired script passing the pipeline test configuration file as input

python meancurvature-train.py experiments/meancurvature_bunny.yaml

8. (Optional) Pass the --kaolin switch to the training scripts to visualize the meshes using NVIDIA Kaolin
9. (Optional) Run tensorboard using the command below and access http://localhost:6006/ to see the training progress

tensorboard --logdir results/meancurvature_bunny/summaries

10. Run the reconstruction script to convert the output model to a series of meshes

python reconstruct.py results/meancurvature_bunny/models/best.pth results/meancurvature_bunny/reconstructions/ -t -0.2 0.0 0.2

11. Run MeshLab and open one the resulting mesh files

meshlab results/meancurvature_bunny/reconstructions/time_-0.2.ply

End Result

If everything works, MeshLab should show the following image (or an image similar to it):

Citation

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

@InProceedings{Novello_2023_ICCV,
    author    = {Novello, Tiago and da Silva, Vin\'icius and Schardong, Guilherme and Schirmer, Luiz and Lopes, H\'elio and Velho, Luiz},
    title     = {Neural Implicit Surface Evolution},
    booktitle = {Proceedings of the IEEE/CVF International Conference on Computer Vision (ICCV)},
    month     = {October},
    year      = {2023},
    url       = {https://openaccess.thecvf.com/content/ICCV2023/html/Novello_Neural_Implicit_Surface_Evolution_ICCV_2023_paper.html},
    pages     = {14279-14289}
}

Contact

If you have any questions, please feel free to email the authors, or open an issue.