Deep3DComp

This is an implementation of our 2023 semester project Deep 3D-Shape Compression. You can read our research report or view a summary of our results on our website. We thank the authors of DeepSDF from whom be borrow code.

File Organization

The various Python scripts assume a shared organizational structure such that the output from one script can easily be used as input to another. This is true for both preprocessed data as well as experiments which make use of the datasets.

Data Layout

The DeepSDF code allows for pre-processing of meshes from multiple datasets and stores them in a unified data source. It also allows for separation of meshes according to class at the dataset level. The structure is as follows:

<data_source_name>/
    .datasources.json
    SdfSamples/
        <dataset_name>/
            <class_name>/
                <instance_name>.npz
    SurfaceSamples/
        <dataset_name>/
            <class_name>/
                <instance_name>.ply

Subsets of the unified data source can be reference using split files, which are stored in a simple JSON format. For examples, see examples/splits/.

The file datasources.json stores a mapping from named datasets to paths indicating where the data came from. This file is referenced again during evaluation to compare against ground truth meshes (see below), so if this data is moved this file will need to be updated accordingly.

Experiment Layout

Each DeepSDF experiment is organized in an "experiment directory", which collects all of the data relevant to a particular experiment. The structure is as follows:

<experiment_name>/
    specs.json
    Logs.pth
    LatentCodes/
        <Epoch>.pth
    ModelParameters/
        <Epoch>.pth
    OptimizerParameters/
        <Epoch>.pth
    Reconstructions/
        <Epoch>/
            Codes/
                <MeshId>.pth
            Meshes/
                <MeshId>.pth
    Evaluations/
        Chamfer/
            <Epoch>.json
        EarthMoversDistance/
            <Epoch>.json
    TensorBoard/
        ReconstructionsTrain/
            <classID_shapeID>/
                <epoch=Epoch>.ply
        ReconstructionsTest/
            <classID_shapeID>/
                <epoch=Epoch>.ply
        TensorBoardLogFile

The only file that is required to begin an experiment is 'specs.json', which sets the parameters, network architecture, and data to be used for the experiment.

How to Use DeepSDF

Pre-processing the Data

In order to use mesh data for training a DeepSDF model, the mesh will need to be pre-processed. This can be done with the preprocess_data.py executable. The preprocessing code is in C++ and has the following requirements:

• CLI11
• Pangolin
• nanoflann
• Eigen3

With these dependencies, the build process follows the standard CMake procedure:

mkdir build
cd build
cmake ..
make -j

Once this is done there should be two executables in the DeepSDF/bin directory, one for surface sampling and one for SDF sampling. With the binaries, the dataset can be preprocessed using preprocess_data.py.

Preprocessing with Headless Rendering

The preprocessing script requires an OpenGL context, and to acquire one it will open a (small) window for each shape using Pangolin. If Pangolin has been compiled with EGL support, you can use the "headless" rendering mode to avoid the windows stealing focus. Pangolin's headless mode can be enabled by setting the PANGOLIN_WINDOW_URI environment variable as follows:

export PANGOLIN_WINDOW_URI=headless://

Training a Model

Once data has been preprocessed, models can be trained using:

python train_deep_sdf.py -e <experiment_directory>

Parameters of training are stored in a "specification file" in the experiment directory, which (1) avoids proliferation of command line arguments and (2) allows for easy reproducibility. This specification file includes a reference to the data directory and a split file specifying which subset of the data to use for training.

Continuing from a Saved Optimization State

If training is interrupted, pass the --continue flag along with a epoch index to train_deep_sdf.py to continue from the saved state at that epoch. Note that the saved state needs to be present --- to check which checkpoints are available for a given experiment, check the `ModelParameters', 'OptimizerParameters', and 'LatentCodes' directories (all three are needed).

Reconstructing Meshes

To use a trained model to reconstruct explicit mesh representations of shapes from the test set, run:

python reconstruct.py -e <experiment_directory>

This will use the latest model parameters to reconstruct all the meshes in the split. To specify a particular checkpoint to use for reconstruction, use the --checkpoint flag followed by the epoch number. Generally, test SDF sampling strategy and regularization could affect the quality of the test reconstructions. For example, sampling aggressively near the surface could provide accurate surface details but might leave under-sampled space unconstrained, and using high L2 regularization coefficient could result in perceptually better but quantitatively worse test reconstructions.

Shape Completion

The current release does not include code for shape completion. Please check back later!

Evaluating Reconstructions

Before evaluating a DeepSDF model, a second mesh preprocessing step is required to produce a set of points sampled from the surface of the test meshes. This can be done as with the sdf samples, but passing the --surface flag to the pre-processing script. Once this is done, evaluations are done using:

python evaluate.py -e <experiment_directory> -d <data_directory> --split <split_filename>

Commonly Used Commands

Here's a list of commands for a typical use case of training and evaluating a DeepSDF model using the "sofa" class of the ShapeNet version 2 dataset.

# navigate to the DeepSdf root directory
cd [...]/DeepSdf

# create a home for the data
mkdir data

# pre-process the sofas training set (SDF samples)
python preprocess_data.py --data_dir data --source [...]/ShapeNetCore.v2/ --name ShapeNetV2 --split examples/splits/sv2_sofas_train.json --skip

# train the model
python train_deep_sdf.py -e examples/sofas
python train_deep_sdf.py -e examples/planes --batch_split 2
python train_deep_sdf.py -e ../../shared/deepsdfcomp/experiments/test_planes_pw/

# pre-process the sofa test set (SDF samples)
python preprocess_data.py --data_dir data --source [...]/ShapeNetCore.v2/ --name ShapeNetV2 --split examples/splits/sv2_sofas_test.json --test --skip

python preprocess_data.py --data_dir /home/shared/deepsdf/data/ --source /mnt/hdd/ShapeNetCore.v2/ --name ShapeNetV2 --split examples/splits/sv2_planes_train.json --skip

# pre-process the sofa test set (surface samples)
python preprocess_data.py --data_dir data --source [...]/ShapeNetCore.v2/ --name ShapeNetV2 --split examples/splits/sv2_sofas_test.json --surface --skip

# reconstruct meshes from the sofa test split (after 2000 epochs)
python reconstruct.py -e examples/sofas -c 2000 --split examples/splits/sv2_sofas_test.json -d data --skip
python reconstruct.py -e examples/planes -c 2000 --split examples/splits/sv2_planes_test.json -d ../../shared/deepsdfcomp/data --skip
python reconstruct.py -e ../../shared/deepsdfcomp/searches/double_nonlinearity/all_latentsize\=200_width\=256_lr\=5e-4_int\=150/ --split ../../shared/deepsdfcomp/experiments/splits/sv2_planes_test.json -d ../../shared/deepsdfcomp/data/ --skip

python reconstruct.py -e examples/planes_single/ -c 2000 --split examples/splits/sv2_planes_train_single.json -d data --skip

# evaluate the reconstructions
python evaluate.py -e examples/sofas -c 2000 -d data -s examples/splits/sv2_sofas_test.json 
python evaluate.py -e examples/planes -c 2000 -d ../../shared/deepsdfcomp/data/ -s examples/splits/sv2_planes_test.json 
python evaluate.py -e ../../shared/deepsdfcomp/searches/double_nonlinearity/line -c 1070 -d ../../shared/deepsdfcomp/data/ -s examples/splits/sv2_planes_test.json

Team

Philipp Wulff and Leonard Freißmuth.

We want thank Prof. Matthias Nießner for supervising our project.

Citation

If you use Deep3DComp in your research, please cite:

@article{freissmuth2023deep3dcomp,
  author    = {Freissmuth, Leonard and Wulff, Philipp},
  title     = {Deep 3D-Shape Compression},
  year      = {2023},
  month     = {Mar},
  url       = {https://philippwulff.github.io/Deep3DComp/}
}