We are More than Our JOints: Predicting How 3D Bodies Move

Citation

This repo contains the official implementation of our paper MOJO:

@inproceedings{Zhang:CVPR:2021,
  title = {We are More than Our Joints: Predicting how {3D} Bodies Move},
  author = {Zhang, Yan and Black, Michael J. and Tang, Siyu},
  booktitle = {Proceedings IEEE/CVF Conf.~on Computer Vision and Pattern Recognition (CVPR)},
  month = jun,
  year = {2021},
  month_numeric = {6}
}

License

We employ CC BY-NC-SA 4.0 for the MOJO code, which covers

models/fittingop.py
experiments/utils/batch_gen_amass.py
experiments/utils/utils_canonicalize_amass.py
experiments/utils/utils_fitting_jts2mesh.py
experiments/utils/vislib.py
experiments/vis_*_amass.py

The rest part are developed based on DLow. According to their license, the implementation follows its CMU license.

Environment & code structure

• Tested OS: Linux Ubuntu 18.04
• Packages:
  • Python >= 3.6
  • PyTorch >= 1.2
  • Tensorboard
  • smplx
  • vposer
  • others
• Note: All scripts should be run from the root of this repo to avoid path issues. Also, please fix some path configs in the code, otherwise errors will occur.

Training

The training is split to two steps. Provided we have a config file in experiments/cfg/amass_mojo_f9_nsamp50.yml, we can do

• python experiments/train_MOJO_vae.py --cfg amass_mojo_f9_nsamp50 to train the MOJO
• python experiments/train_MOJO_dlow.py --cfg amass_mojo_f9_nsamp50 to train the DLow

Evaluation

These experiments/eval_*.py files are for evaluation. For eval_*_pred.py, they can be used either to evaluate the results while predicting, or to save results to a file for further evaluation and visualization. An example is python experiments/eval_kps_pred.py --cfg amass_mojo_f9_nsamp50 --mode vis, which is to save files to the folder results/amass_mojo_f9_nsamp50.

Generation

In MOJO, the recursive projection scheme is to get 3D bodies from markers and keep the body valid. The relevant implementation is mainly in models/fittingop.py and experiments/test_recursive_proj.py. An example to run is

python experiments/test_recursive_proj.py --cfg amass_mojo_f9_nsamp50 --testdata ACCAD --gpu_index 0

Datasets

In MOJO, we have used AMASS, Human3.6M, and HumanEva.

For Human3.6M and HumanEva, we follow the same pre-processing step as in DLow, VideoPose3D, and others. Please refer to their pages, e.g. this one, for details.

For AMASS, we perform canonicalization of motion sequences with our own procedures. The details are in experiments/utils_canonicalize_amass.py. We find this sequence canonicalization procedure is important. The canonicalized AMASS used in our work can be downloaded here, which includes the random sample names of ACCAD and BMLhandball used in our experiments about motion realism.

Models

For human body modeling, we employ the SMPL-X parametric body model. You need to follow their license and download. Based on SMPL-X, we can use the body joints or a sparse set of body mesh vertices (the body markers) to represent the body.

• CMU It has 41 markers, the corresponding SMPL-X mesh vertex ID can be downloaded here.
• SSM2 It has 64 markers, the corresponding SMPL-X mesh vertex ID can be downloaded here.
• Joints We used 22 joints. No need to download, but just obtain them from the SMPL-X body model. See details in the code.

Our CVAE model configurations are in experiments/cfg. The pre-trained checkpoints can be downloaded here.

Related projects

• AMASS: It unifies diverse motion capture data with the SMPL-H model, and provides a large-scale high-quality dataset. Its official codebase and tutorials are in this github repo.

• GRAB: Most mocap data only contains the body motion. GRAB, however, provides high-quality data of human-object interactions. Besides capturing the body motion, the object motion and the hand-object contact are captured simultaneously. More demonstrations are in its github repo.

Acknowledgement & disclaimer

We thank Nima Ghorbani for the advice on the body marker setting and the {\bf AMASS} dataset. We thank Yinghao Huang, Cornelia K"{o}hler, Victoria Fern'{a}ndez Abrevaya, and Qianli Ma for proofreading. We thank Xinchen Yan and Ye Yuan for discussions on baseline methods. We thank Shaofei Wang and Siwei Zhang for their help with the user study and the presentation, respectively.

MJB has received research gift funds from Adobe, Intel, Nvidia, Facebook, and Amazon. While MJB is a part-time employee of Amazon, his research was performed solely at, and funded solely by, Max Planck. MJB has financial interests in Amazon Datagen Technologies, and Meshcapade GmbH.