SDF-SRN: Learning Signed Distance 3D Object Reconstruction from Static Images

Chen-Hsuan Lin, Chaoyang Wang, and Simon Lucey
Advances in Neural Information Processing Systems (NeurIPS), 2020

Project page: https://chenhsuanlin.bitbucket.io/signed-distance-SRN
Paper: https://chenhsuanlin.bitbucket.io/signed-distance-SRN/paper.pdf
arXiv preprint: https://arxiv.org/abs/2010.10505

We provide PyTorch code for both the ShapeNet and PASCAL3D+ experiments.

---

Prerequisites

This code is developed with Python3 (python3). PyTorch 1.4+ is required.
It is recommended to install the dependencies with conda by running

conda env create --file requirements.yaml python=3

This creates a conda environment named sdfsrn-env. Activate it with

conda activate sdfsrn-env

You may want to install with virtualenv; however, this repository depends on VIGRA to compute the distance transforms, which does not seem to be pip installable. Some workarounds would include (a) installing VIGRA from source, or (b) replacing the VIGRA distance transform function with scipy.ndimage.distance_transform_edt (significantly slower).

---

Dataset

• ShapeNet

  Download the ShapeNet renderings of Kato et al. from the DVR repository (33GB):
  (this file is huge and takes a long time to fully unzip, so we extract only the 3 categories of interest in this work)

  wget https://s3.eu-central-1.amazonaws.com/avg-projects/differentiable_volumetric_rendering/data/NMR_Dataset.zip
  unzip NMR_Dataset.zip NMR_Dataset/02691156/* # airplane
  unzip NMR_Dataset.zip NMR_Dataset/02958343/* # car
  unzip NMR_Dataset.zip NMR_Dataset/03001627/* # chair
  rm NMR_Dataset.zip

  In the data/NMR_Dataset directory, download the post-processed surface point clouds:

  wget https://cmu.box.com/shared/static/yvencf3ts8itfgyuh5sap9q7dy5r1elg.gz
  tar -zxvf yvencf3ts8itfgyuh5sap9q7dy5r1elg.gz
  rm yvencf3ts8itfgyuh5sap9q7dy5r1elg.gz

  There should be a pointcloud3.npz within each shape directory, along with the original pointcloud.npz. You can check with

  ls NMR_Dataset/02691156/10155655850468db78d106ce0a280f87

  If you're interested in creating ground-truth point clouds for other object categories, please refer to the README in data.

• PASCAL3D+

  Download the PASCAL3D+ (v1.1) dataset under the data directory (7.7GB):

  wget ftp://cs.stanford.edu/cs/cvgl/PASCAL3D+_release1.1.zip
  unzip PASCAL3D+_release1.1.zip
  rm PASCAL3D+_release1.1.zip

  Also under the data directory, download the object masks and ground-truth point clouds for the 3 categories (23MB):

  wget https://cmu.box.com/shared/static/uyz0txthw0ufjwury0f3z3iuhqdbaet9.gz
  tar -zxvf uyz0txthw0ufjwury0f3z3iuhqdbaet9.gz
  rm uyz0txthw0ufjwury0f3z3iuhqdbaet9.gz

---

Pretrained models

First, create a directory to store the pretrained models:

mkdir -p pretrained

Then under pretrained, download the pretrained model(s) by running the commands

# ShapeNet (trained on multi-view renderings, 615MB each)
wget https://cmu.box.com/shared/static/cgrzlaudm2ojs5l3nmmbbr7ovsvbqhtv.ckpt -O shapenet_airplane.ckpt  # airplane
wget https://cmu.box.com/shared/static/lclrhwae5xu6z7f2fc3qnkeon3q5ljfg.ckpt -O shapenet_car.ckpt  # car
wget https://cmu.box.com/shared/static/58dsppp8hq0yqj216tqm573or9porq2m.ckpt -O shapenet_chair.ckpt  # chair
# PASCAL3D+ (197MB each)
wget https://cmu.box.com/shared/static/gvslqtye7p0pzgaspmwvq7pggnmxsu3x.ckpt -O pascal3d_airplane.ckpt # airplane
wget https://cmu.box.com/shared/static/kh8mrrufol3u1mm6duaym5sygfd42d5p.ckpt -O pascal3d_car.ckpt # car
wget https://cmu.box.com/shared/static/ty0ywyeud1n1n9uu169xoag9m35me267.ckpt -O pascal3d_chair.ckpt # chair

---

Compiling the CUDA libraries

The Chamfer distance function can be compiled by running python3 setup.py install under external/chamfer3D. The source code is taken/modified from the AtlasNet repository.
When compiling CUDA code, you may need to modify CUDA_PATH accordingly.

---

Running the code

• Evaluating the downloaded pretrained models

  # ShapeNet (trained on multi-view renderings)
  python3 evaluate.py --model=sdf_srn --yaml=options/shapenet/sdf_srn.yaml --name=airplane_pretrained --data.shapenet.cat=plane --load=pretrained/shapenet_airplane.ckpt --tb= --visdom= --eval.vox_res=128
  python3 evaluate.py --model=sdf_srn --yaml=options/shapenet/sdf_srn.yaml --name=car_pretrained --data.shapenet.cat=car --load=pretrained/shapenet_car.ckpt --tb= --visdom= --eval.vox_res=128
  python3 evaluate.py --model=sdf_srn --yaml=options/shapenet/sdf_srn.yaml --name=chair_pretrained --data.shapenet.cat=chair --load=pretrained/shapenet_chair.ckpt --tb= --visdom= --eval.vox_res=128
  # PASCAL3D+
  python3 evaluate.py --model=sdf_srn --yaml=options/pascal3d/sdf_srn.yaml --name=airplane_pretrained --data.pascal3d.cat=plane --load=pretrained/pascal3d_airplane.ckpt --tb= --visdom= --eval.vox_res=128 --eval.icp
  python3 evaluate.py --model=sdf_srn --yaml=options/pascal3d/sdf_srn.yaml --name=car_pretrained --data.pascal3d.cat=car --load=pretrained/pascal3d_car.ckpt --tb= --visdom= --eval.vox_res=128 --eval.icp
  python3 evaluate.py --model=sdf_srn --yaml=options/pascal3d/sdf_srn.yaml --name=chair_pretrained --data.pascal3d.cat=chair --load=pretrained/pascal3d_chair.ckpt --tb= --visdom= --eval.vox_res=128 --eval.icp

  This will create the following files in the output directory (e.g. output/sdf_srn_pascal3d/car_pretrained):

  • chamfer.txt: the (bidirectional) Chamfer distance error for each example.
  • dump/*_mesh.ply: the resulting 3D meshes (from zero isosurface extraction with marching cubes).
  • dump/*.png: images including input/rendered RGB images, input/predicted masks, depth maps and surface normal maps.
  • dump/vis.html: a webpage to visualize all the images for convenience.

  The overall Chamfer distance error (the numbers reported in the paper) will also be shown on screen.
  Note that it takes longer to evaluate the PASCAL3D+ models since we run ICP to pre-align the predictions to the ground-truth shapes.

• Training from scratch

  To train SDF-SRN, we first quickly pretrain the generator with a spherical SDF for 1000 iterations with:

  # ShapeNet
  python3 train.py --model=sdf_srn_pretrain --yaml=options/shapenet/sdf_srn_pretrain.yaml
  # PASCAL3D+
  python3 train.py --model=sdf_srn_pretrain --yaml=options/pascal3d/sdf_srn_pretrain.yaml

  This helps SDF-SRN converge to a feasible solution, otherwise it may get stuck in bad local minima.

  For the main training:

  # ShapeNet (~100K iterations for airplanes and cars, ~200K iterations for chairs)
  python3 train.py --model=sdf_srn --yaml=options/shapenet/sdf_srn.yaml --name=airplane --data.shapenet.cat=plane --max_epoch=24 --loss_weight.shape_silh=1
  python3 train.py --model=sdf_srn --yaml=options/shapenet/sdf_srn.yaml --name=car --data.shapenet.cat=car --max_epoch=27
  python3 train.py --model=sdf_srn --yaml=options/shapenet/sdf_srn.yaml --name=chair --data.shapenet.cat=chair --max_epoch=28
  # PASCAL3D+ (~30K iterations)
  python3 train.py --model=sdf_srn --yaml=options/pascal3d/sdf_srn.yaml --name=airplane --data.pascal3d.cat=plane --freq.eval=30 --freq.ckpt=30 --max_epoch=500
  python3 train.py --model=sdf_srn --yaml=options/pascal3d/sdf_srn.yaml --name=car --data.pascal3d.cat=car --freq.eval=10 --freq.ckpt=10 --max_epoch=170
  python3 train.py --model=sdf_srn --yaml=options/pascal3d/sdf_srn.yaml --name=chair --data.pascal3d.cat=chair --freq.eval=60 --freq.ckpt=60 --max_epoch=900

  The above command for ShapeNet runs single-view training on multi-view data. To train on single-view ShapeNet data (only 1 view is available per CAD model) with the reported settings, run

  # single-view ShapeNet chairs (~50K iterations)
  python3 train.py --model=sdf_srn --yaml=options/shapenet/sdf_srn.yaml --name=chair_1view_1kcad --data.shapenet.cat=chair --data.shapenet.train_view=1 --data.train_sub=1000 --data.augment.brightness=0.2 --data.augment.contrast=0.2 --data.augment.saturation=0.2 --data.augment.hue=0.5 --freq.eval=100 --freq.ckpt=100 --max_epoch=800

  This trains on a subset of 1000 chair CAD models with 1 viewpoint each while randomly jittering the colors.

  To evaluate the trained models:

  # ShapeNet
  python3 evaluate.py --model=sdf_srn --yaml=options/shapenet/sdf_srn.yaml --name=airplane --data.shapenet.cat=plane --tb= --visdom= --eval.vox_res=128 --resume
  python3 evaluate.py --model=sdf_srn --yaml=options/shapenet/sdf_srn.yaml --name=car --data.shapenet.cat=car --tb= --visdom= --eval.vox_res=128 --resume
  python3 evaluate.py --model=sdf_srn --yaml=options/shapenet/sdf_srn.yaml --name=chair --data.shapenet.cat=chair --tb= --visdom= --eval.vox_res=128 --resume
  # PASCAL3D+
  python3 evaluate.py --model=sdf_srn --yaml=options/pascal3d/sdf_srn.yaml --name=airplane --data.pascal3d.cat=plane --tb= --visdom= --eval.vox_res=128 --eval.icp --resume
  python3 evaluate.py --model=sdf_srn --yaml=options/pascal3d/sdf_srn.yaml --name=car --data.pascal3d.cat=car --tb= --visdom= --eval.vox_res=128 --eval.icp --resume
  python3 evaluate.py --model=sdf_srn --yaml=options/pascal3d/sdf_srn.yaml --name=chair --data.pascal3d.cat=chair --tb= --visdom= --eval.vox_res=128 --eval.icp --resume

  The expected output is similar to those described above (in the pretrained models section).

• Visualizing the results

  We have included code to visualize the training over TensorBoard. The TensorBoard events include the following:

  • SCALARS: the losses and bidirectional Chamfer distances (for both training and validation sets).
  • IMAGES: visualization of the RGB/mask/depth/normal images.

  We also provide visualization of dense point clouds sampled on the zero isosurface in Visdom.

• General usage of the codebase

  The simplest command to run training is:

  python3 train.py --model=sdf_srn

  This will run model/sdf_srn.py as the main engine with options/sdf_srn.yaml as the main config file. Note that sdf_srn is hierarchically inherited from implicit and base, which makes the codebase customizable.
  The complete configuration will be printed upon execution. To override specific options, add --<key>=value or --<key1>.<key2>=value (and so on) to the command line. The configuration will be loaded as the variable opt throughout the codebase.
  If you want to reproduce the reported results, load preset configurations with the yaml option (details below).

  Some tips on using and understanding the codebase:

  • The computation graph for forward/backprop is stored in var throughout the codebase.
  • The losses are stored in loss. To add a new loss function, just implement it in compute_loss() and add its weight to opt.loss_weight.<name>. It will automatically be added to the overall loss and logged to Tensorboard.
  • If you are using a multi-GPU machine, you can add --gpu=<gpu_number> to specify which GPU to use. Multi-GPU training/evaluation is currently not supported.
  • To resume from a previous checkpoint, add --resume=<epoch_number>, or just --resume to resume from the latest checkpoint.
  • (to be continued....)

---

If you find our code useful for your research, please cite

@inproceedings{lin2020sdfsrn,
  title={SDF-SRN: Learning Signed Distance 3D Object Reconstruction from Static Images},
  author={Lin, Chen-Hsuan and Wang, Chaoyang and Lucey, Simon},
  booktitle={Advances in Neural Information Processing Systems ({NeurIPS})},
  year={2020}
}

Please contact me ([email protected]) if you have any questions!