MinBackProp – Backpropagating through Minimal Solvers

Source code for the paper MinBackProp – Backpropagating through Minimal Solvers

Outlier Detection for Essential Matrix Estimation

We evaluate our MinBackProp on outlier detection for essential matrix estimation. This code is based on the baseline ∇-RANSAC we compare with; the forward pass is the same for both the baseline and MinBackProp, while the backward pass differs ($\color{rgb(192,0,0)}{\text{Autograd}}$ vs $\color{rgb(0,112,192)}{\text{DDN}}$ / $\color{rgb(0,176,80)}{\text{IFT}}$).

Requirements and installation

Install the required packages

python = 3.8.10	
pytorch = 1.12.1
opencv = 3.4.2
tqdm
kornia
kornia_moons
tensorboardX
scikit-learn
einops
yacs

For inference, build MAGSAC++ with

git clone https://github.com/disungatullina/magsac.git --recursive
cd magsac
mkdir build
cd build
cmake ..
make
cd ..
python setup.py install

Then clone the project with submodules

git clone https://github.com/disungatullina/MinBackProp.git --recurse-submodules -j8
cd MinBackProp

Training

Use -ift 1 for the IFT, -ift 2 for the DDN, and -ift 0 for Autograd (baseline). Default is -ift 1.

python train.py -ift 1 -nf 2000 -m pretrained_models/weights_init_net_3_sampler_0_epoch_1000_E_rs_r0.80_t0.00_w1_1.00_.net -bs 32 -e 10 -tr 1 -t 0.75 -pth <data_path>

Evaluation

Models for inference are stored in the models directory.

python test_magsac.py -nf 2000 -m models/ift.net -bs 32 -bm 1 -t 2 -pth <data_path>

Dataset

Download the RootSIFT features of the PhotoTourism dataset from here.

Command line arguments

-ift: backprop method to use, 0-autograd, 1-ift, 2-ddn, default=1
-pth: path to the dataset
-nf: number of features, default=2000
-m: pretrained model to init or trained model for inference
-bs: batch size, default=32
-e: the number of epochs, default=10
-tr: train or test mode, default=0
-t: threshold, default=0.75
-lr: learning rate, default=1e-4
-bm: batch mode, using all the 12 testing scenes defined in utils.py, default=0
-ds: name of a scene, if single scene used, default="st_peters_square"

See more command line arguments in utils.py.

Docker image

The current Docker image is built for CPU usage. If you need a GPU version, please modify the Dockerfile accordingly.

docker pull dsungatullina/minbackprop
docker run -it dsungatullina/minbackprop

For training, run the following command

python3 train.py -ift 1 -nf 2000 -m pretrained_models/weights_init_net_3_sampler_0_epoch_1000_E_rs_r0.80_t0.00_w1_1.00_.net -bs 32 -e 10 -tr 1 -t 0.75 -pth data 

To start the inference, run

python3 test_magsac.py -nf 2000 -m models/ift.net -bs 32 -bm 1 -t 2 -pth data

Toy examples

3D Point Registration with an Outlier

cd toy_examples
python estimate_rotation.py --ift --ddn --autograd --plot

Fundamental Matrix Estimation with an Outlier

cd toy_examples
python estimate_fundamental.py --ift --ddn --autograd --plot

Citation

If you use our algorithm, please cite

@ARTICLE{Sungatullina2024-A83,
author={Diana Sungatullina and Tomas Pajdla},
title={MinBackProp – Backpropagating through Minimal Solvers},
journal={Journal of WSCG},
year={2024},
volume={32},
number = {1-2},
pages={41-50},
doi={10.24132/JWSCG.2024.5},
publisher={Union Agency, Science Press},
issn={1213-6972},
abbrev_source_title={J WSCG},
document_type={Article},
}