OSRT: Object Scene Representation Transformer

This is an independent PyTorch implementation of OSRT, as presented in the paper "Object Scene Representation Transformer" by Sajjadi et al. All credit for the model goes to the original authors.

Setup

git clone -r git@github.com:alexcbb/OSRT-experiments.git After cloning the repository and creating a new conda environment, the following steps will get you started:

Data

The code currently supports the following datasets. Simply download and place (or symlink) them in the data directory.

• The 3D datasets introduced by ObSuRF.
• OSRT's MultiShapeNet (MSN-hard) dataset. It may be downloaded via gsutil:

pip install gsutil
mkdir -p data/osrt/multi_shapenet_frames/
gsutil -m cp -r gs://kubric-public/tfds/kubric-frames/multi_shapenet_conditional/2.8.0/ data/osrt/multi_shapenet_frames/

Dependencies

This code requires at least Python 3.9 and PyTorch 1.11. Additional dependencies may be installed via pip -r requirements.txt. Note that Tensorflow is required to load OSRT's MultiShapeNet data, though the CPU version suffices.

Rendering videos additionally depends on ffmpeg>=4.3 being available in your $PATH.

To install Segment Anything dependencies :

cd segment-anything/

pip install -e

Running Experiments

Each run's config, checkpoints, and visualization are stored in a dedicated directory. Recommended configs can be found under runs/[dataset]/[model].

Training

To train a model on a single GPU, simply run e.g.:

python train.py runs/clevr3d/osrt/config.yaml

To train on multiple GPUs on a single machine, launch multiple processes via Torchrun, where $NUM_GPUS is the number of GPUs to use:

torchrun --standalone --nnodes 1 --nproc_per_node $NUM_GPUS train.py runs/clevr3d/osrt/config.yaml

Checkpoints are automatically stored in and (if available) loaded from the run directory. Visualizations and evaluations are produced periodically. Check the args of train.py for additional options. Importantly, to log training progress, use the --wandb flag to enable Weights & Biases.

Rendering videos

Videos may be rendered using render.py, e.g.

python render.py runs/msn/osrt/config.yaml --sceneid 1 --motion rotate_and_closeup --fade

Rendered frames and videos are placed in the run directory. Check the args of render.py for various camera movements, and compile_video.py for different ways of compiling videos.

Results

We have found OSRT's object segmentation performance to be strongly dependent on the batch sizes used during training. Due to memory constraints, we were unable to match OSRT's settings on MSN-hard. Our largest and most successful run thus far utilized 2304 target rays per scene as opposed to the 8192 specified in the paper. It reached a foreground ARI of around 0.73 and a PSNR of 22.8 after 750k iterations. For download, we provide both the checkpoint and a sample video.

To match the memory availability of your hardware, consider adjusting data/num_points or training/batch_size in config.yaml. However, setting these too low can make the model prone to getting stuck in local optima, especially early in training.

Citation

@article{sajjadi2022osrt,
  author = {Sajjadi, Mehdi S. M.
			and Duckworth, Daniel
			and Mahendran, Aravindh
			and van Steenkiste, Sjoerd
			and Paveti{\'c}, Filip
			and Lu{\v{c}}i{\'c}, Mario
			and Guibas, Leonidas J.
			and Greff, Klaus
			and Kipf, Thomas
			},
  title = {{Object Scene Representation Transformer}},
  journal = {NeurIPS},
  year  = {2022}
}