Detector-Free Structure from Motion

Project Page | Paper

Detector-Free Structure from Motion
Xingyi He, Jiaming Sun, Yifan Wang, Sida Peng, Qixing Huang, Hujun Bao, Xiaowei Zhou
CVPR 2024, 1st in Image Matching Challenge 2023

Installation

Please refer to INSTALL.md for installation instructions.

Prepare Dataset

The data structure of our system is organized as follows:

repo_path/SfM_dataset
    - dataset_name1
        - scene_name_1
            - images
                - image_name_1.jpg or .png or ...
                - image_name_2.jpg
                - ...
            - intrins (optional, used for evaluation)
                - camera_name_1.txt
                - camera_name_2.txt
                - ...
            - poses (optional, used for evaluation)
                - pose_name_1.txt
                - pose_name_2.txt
                - ...
        - scene_name_2
            - ...
    - dataset_name2
        - ...

The folder naming of images, intrins and poses is compulsory, for the identification by our system.

Now, download the training and evaluation datasets, and then format them to required structure following instructions in DATASET_PREPARE.md.

Run Demo data

First modify L22 in hydra_configs/demo/dfsfm.yaml to specify the absolute path of the repo. Then run the following command:

python eval_dataset.py +demo=dfsfm.yaml

SfM result will be saved in SfM_dataset/example_dataset/example_scene/DetectorFreeSfM_loftr_official_coarse_only__scratch_no_intrin/colmap_refined in COLMAP format, and can be visualized by colmap gui.

Evaluation

SfM Evaluation

# For ETH3D dataset:
python eval_dataset.py +eth3d_sfm=dfsfm.yaml neuralsfm.NEUSFM_coarse_matcher='loftr_official'
python eval_dataset.py +eth3d_sfm=dfsfm.yaml neuralsfm.NEUSFM_coarse_matcher='aspanformer'
python eval_dataset.py +eth3d_sfm=dfsfm.yaml neuralsfm.NEUSFM_coarse_matcher='matchformer'

# For IMC dataset:
sh scripts/eval_imc_dataset.sh

# For TexturePoorSfM dataset:
sh scripts/eval_texturepoorsfm_dataset.sh

Triangulation evaluation

# For ETH3D dataset:
python eval_dataset.py +eth3d_tri=dfsfm.yaml neuralsfm.NEUSFM_coarse_matcher='loftr_official'
python eval_dataset.py +eth3d_tri=dfsfm.yaml neuralsfm.NEUSFM_coarse_matcher='aspanformer'
python eval_dataset.py +eth3d_tri=dfsfm.yaml neuralsfm.NEUSFM_coarse_matcher='matchformer'

Tips about speed up

1. You can speed up evaluation by enable multi-processing if you have multiple GPUs. You can set ray.enable=True and set ray.n_workers=your_gpu_number the configs to simutaneously evaluate many scenes within a dataset.
2. For a scene with many images, like Bridge in the ETH3D dataset, you can set multiple workers for image matching in coarse SfM and multi-view refinement matching phase by setting sub_use_ray=True and sub_ray_n_worker=your_gpu_number
3. Increase batchsize in multi-view refinement phase. Currently, we chunk the tracks in refinement matching and neuralsfm.NEUSFM_refinement_chunk_size is set to 2000 so that it can work on GPU with VRAM less than 12GB. If the GPUs in your device are with larger VRAM, you can consider increase this value to speed up the process.

Train Multiview Matching Refiner

Be sure you have downloaded and formated the MegaDepth dataset following DATASET_PREPARE.md.

python train_multiview_matcher.py +experiment=multiview_refinement_matching.yaml paths=dataset_path_config trainer=trainer_config

You can modify the GPU ids in hydra_training_configs/trainer/trainer_config.yaml. By default, we use 8 GPUs for training.

Acknowledgement

Our code is partally based on COLMAP and HLoc, we thank the authors for their great work.

Citation

If you find this code useful for your research, please use the following BibTeX entry.

@article{he2024dfsfm,
  title={Detector-Free Structure from Motion},
  author={He, Xingyi and Sun, Jiaming and Wang, Yifan and Peng, Sida and Huang, Qixing and Bao, Hujun and Zhou, Xiaowei},
  journal={{CVPR}},
  year={2024}
}