> `PS:` In our implementation, we use pytorch built-in operators to simulate the submanifold sparse convolution in [encoder.py](https://github.com/keyu-tian/SparK/blob/main/pretrain/encoder.py) for generality,
due to the fact that many convolution operators (e.g., grouped conv and dilated conv) do not yet have efficient sparse implementations on today's hardware.
If you want to try those sparse convolution, you may refer to [this](https://github.com/facebookresearch/SparseConvNet) sparse convolution library or [MinkowskiEngine](https://github.com/NVIDIA/MinkowskiEngine).