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Fast Point Cloud Generation with Straight Flows
Lemeng Wu, Dilin Wang, Chengyue Gong, Xingchao Liu, Yunyang Xiong, Rakesh Ranjan, Raghuraman Krishnamoorthi, Vikas Chandra, Qiang Liu

About This Code:

Now we release code for training and inference. Some works are still in progress including pretrained checkpoint.

Requirements:

This code is largely build based on PVD. Make sure at least the following environments are installed (newer version may also works, we test in the below environments).

python==3.8
pytorch==1.4.0
torchvision==0.5.0
cudatoolkit==10.1
matplotlib==2.2.5
tqdm==4.32.1
open3d==0.9.0
trimesh=3.7.12
scipy==1.5.1

We also need to install pytorch3D for Chamfer Distance Loss, we recommend to follow the offical install guideline here

Install PyTorchEMD by

cd metrics/PyTorchEMD
python setup.py install
cp build/**/emd_cuda.cpython-36m-x86_64-linux-gnu.so .

Data

We use the data follow PVD and PointFlow, which can be downloaded here. Extract and put the data in ./data/ folder/

Train:

First Stage, train the flow model. We do not add EMA here for a simple and quick converge as illustration.

$ python train_flow.py --category car|chair|airplane

Assume the checkpoint is saved as flow_checkpoint.pth (you can find it in the ./output/train_flow/ )

Second Stage, straight the flow, first sample the data pairs. We provide a single GPU version, in practice, we use multiGPU to speed up.

$ python sample_flow.py --category car|chair|airplane --model flow_checkpoint.pth

Then run the reflow procedure:

$ python train_reflow.py --category car|chair|airplane --model flow_checkpoint.pth

Assume the checkpoint is saved as reflow_checkpoint.pth (you can find it in the ./output/train_reflow/ )

Third Stage, distill the flow.

$ python train_distill.py --category car|chair|airplane --model reflow_checkpoint.pth

Assume the checkpoint is saved as distill_checkpoint.pth (you can find it in the ./output/train_distill/ )

Test:

$ python test_flow.py --category car|chair|airplane --model {flow|reflow|distill}_checkpoint.pth --step 1|20|50|100|500|1000

You can adjust the step in this test code. For flow, reflow model, we can still expect a good few-step generation.

Reference

@InProceedings{Wu_2023_CVPR,
    author    = {Wu, Lemeng and Wang, Dilin and Gong, Chengyue and Liu, Xingchao and Xiong, Yunyang and Ranjan, Rakesh and Krishnamoorthi, Raghuraman and Chandra, Vikas and Liu, Qiang},
    title     = {Fast Point Cloud Generation With Straight Flows},
    booktitle = {Proceedings of the IEEE/CVF Conference on Computer Vision and Pattern Recognition (CVPR)},
    month     = {June},
    year      = {2023},
    pages     = {9445-9454}
}

Acknowledgement:

This code is built based on PVD. Thanks for their great code repo!