CSDNet

Pytorch implmentation of CSDNet (2021) - Omnidirectional stereo depth estimation based on spherical deep network

Introduction

This paper proposes a novel approach that use spherical CNNs and the epipolar constraint on sphere for omnidirectional depth estimation.

CSDNet using a cascade structure to obtain depth maps from left and right 360$^\circ$ images. First convert the ERP domain 360$^\circ$ images to sphere signals and use Spherical Convolution Residual Network (SCRN) to estimate initial depth maps. Then finetune the results based on the initial depth maps and left & right RGB images via the Planar Refinement Network (PRN).

SCRN is built with the Mesh CNNs, which is a type of spherical convolution that convert imgaes to sphere signals and then adopt the convolution operator. SCRN is used for depth estimation of sphere signals.

PRN is a planar refinement network and ti is used to refine the depth maps on ERP domain.

Requirements

pytorch >= 1.6.0

numpy

igl

scipy

pretrained models

The pretrained models of CSDNet on 3D60 and Matterport3D can be downloaded via this link

Dataset

We use the dataset 3D60. It comprises multi-modal stereo renders of scenes from realistic and synthetic large-scale 3D datasets (Matterport3D, Stanford2D3D, SunCG).

The structure of the dataset folder is as follow:

3D60
├── Center_Left_Down
    │ ├── Matterport3D
    │   ├── xxx_color_0_Left_Down_0.0.png
    │   ├── xxx_depth_0_Left_Down_0.0.exr
    │ ├── Stanford2D3D
    │ ├── SunCG
├── Right
    │ ├── Matterport3D
    │   ├── xxx_color_0_Right_0.0.png
    │   ├── xxx_depth_0_Right_0.0.exr
    │ ├── Stanford2D3D
    │ ├── SunCG
├── Up
    │ ├── Matterport3D
    │   ├── xxx_color_0_Up_0.0.png
    │   ├── xxx_depth_0_Up_0.0.exr
    │ ├── Stanford2D3D
    │ ├── SunCG

Usage

install requirements

Please install the required packages above before running the training and testing codes.

generate mesh files

To run the CSDNet, you need to generate the mesh CNN files first. The mesh files indicate the rules that sample ERP images to sphere signals.

python gen_mesh.py

This will create a direcoty names "meshfiles" and 8 mesh files in it. The number in the name of each file is the mesh level. Briefly, the higher the level is, the more sampling points that the mesh contais. you can also download the mesh files directly from this link https://drive.google.com/file/d/1TgO4mSmRFXLr5WR8uH31m4fgCvrqYpKd/view?usp=share_link.

generate mesh2ERP interpolation maps

The mesh2ERP interpolation maps is used to re-project the sphere signals to ERP images. If the file './interMapFiles/interMap_6-1d.npy' does not exist, please run python gen_interMap.py to genearte the file.

If you need to run the model with different mesh levels, please modified the parameters in gen_interMap.py and run the command above.

train CSDNet

Follow this example to train

python train.py --train_files [path to train list] --val_files [path to validation list]

test CSDNet

Follow this example to test

python test.py --filename_list [path to test list] --dataset_root [path to dataset] --load_ckpt [path to checkpoint] --spherical_metrics --save_output --save_dir [path to directory to save results]

Note

1. The Mesh CNN is generated and used with reference to maxjiang93/ugscnn. The codes of spherical utils (i.e. sperical weights, smoothness loss) and dataloader reference VCL3D/SphericalViewSynthesis. We sincerely appericiate these exciting and helpful works.
2. We use the same dataloader for 3D60 and all other relevant datasets (Matterport3D, Stanford2D3D, SunCG), just choose different file_list.txt to control the input data.
3. The train/val/test split of 3D60 that we used is one of the official splits in VCL3D/3D60. For the datasets Matterport3D and SunCG, we used our own splits.

Citation

If you find this project helpful in your research, welcome to cite the paper.

@article{Li2021csdnet,
  title    = {Omnidirectional stereo depth estimation based on spherical deep network},
  journal  = {Image and Vision Computing},
  volume   = {114},
  pages    = {104264},
  year     = {2021},
  issn     = {0262-8856},
  doi      = {https://doi.org/10.1016/j.imavis.2021.104264},
  url      = {https://www.sciencedirect.com/science/article/pii/S0262885621001694},
  author   = {Ming Li and Xuejiao Hu and Jingzhao Dai and Yang Li and Sidan Du},
  keywords = {Omnidirectional depth estimation, Spherical convolutional network, Stereo matching, Cascade learning}
}