Weighted boxes fusion
Repository contains Python implementation of several methods for ensembling boxes from object detection models:
- Non-maximum Suppression (NMS)
- Soft-NMS [1]
- Non-maximum weighted (NMW) [2]
- Weighted boxes fusion (WBF) [3] - new method which gives better results comparing to others
Requirements
Python 3.*, Numpy, Numba
Installation
pip install ensemble-boxes
Usage examples
Coordinates for boxes expected to be normalized e.g in range [0; 1]. Order: x1, y1, x2, y2.
Example of boxes ensembling for 2 models below.
- First model predicts 5 boxes, second model predicts 4 boxes.
- Confidence scores for each box model 1: [0.9, 0.8, 0.2, 0.4, 0.7]
- Confidence scores for each box model 2: [0.5, 0.8, 0.7, 0.3]
- Labels (classes) for each box model 1: [0, 1, 0, 1, 1]
- Labels (classes) for each box model 2: [1, 1, 1, 0]
- We set weight for 1st model to be 2, and weight for second model to be 1.
- We set intersection over union for boxes to be match: iou_thr = 0.5
- We skip boxes with confidence lower than skip_box_thr = 0.0001
from ensemble_boxes import *
boxes_list = [[
[0.00, 0.51, 0.81, 0.91],
[0.10, 0.31, 0.71, 0.61],
[0.01, 0.32, 0.83, 0.93],
[0.02, 0.53, 0.11, 0.94],
[0.03, 0.24, 0.12, 0.35],
],[
[0.04, 0.56, 0.84, 0.92],
[0.12, 0.33, 0.72, 0.64],
[0.38, 0.66, 0.79, 0.95],
[0.08, 0.49, 0.21, 0.89],
]]
scores_list = [[0.9, 0.8, 0.2, 0.4, 0.7], [0.5, 0.8, 0.7, 0.3]]
labels_list = [[0, 1, 0, 1, 1], [1, 1, 1, 0]]
weights = [2, 1]
iou_thr = 0.5
skip_box_thr = 0.0001
sigma = 0.1
boxes, scores, labels = nms(boxes_list, scores_list, labels_list, weights=weights, iou_thr=iou_thr)
boxes, scores, labels = soft_nms(boxes_list, scores_list, labels_list, weights=weights, iou_thr=iou_thr, sigma=sigma, thresh=skip_box_thr)
boxes, scores, labels = non_maximum_weighted(boxes_list, scores_list, labels_list, weights=weights, iou_thr=iou_thr, skip_box_thr=skip_box_thr)
boxes, scores, labels = weighted_boxes_fusion(boxes_list, scores_list, labels_list, weights=weights, iou_thr=iou_thr, skip_box_thr=skip_box_thr)
Single model
If you need to apply NMS or any other method to single model predictions you can call function like that:
from ensemble_boxes import *
# Merge boxes for single model predictions
boxes, scores, labels = weighted_boxes_fusion([boxes_list], [scores_list], [labels_list], weights=None, method=method, iou_thr=iou_thr, thresh=thresh)
More examples can be found in example.py
3D version
There is support for 3D boxes in WBF method with weighted_boxes_fusion_3d
function. Check example of usage in example_3d.py
Accuracy and speed comparison
Comparison was made for ensemble of 5 different object detection models predictions trained on Open Images Dataset (500 classes).
Model scores at local validation:
- Model 1: mAP(0.5) 0.5164
- Model 2: mAP(0.5) 0.5019
- Model 3: mAP(0.5) 0.5144
- Model 4: mAP(0.5) 0.5152
- Model 5: mAP(0.5) 0.4910
Method | mAP(0.5) Result | Best params | Elapsed time (sec) |
---|---|---|---|
NMS | 0.5642 | IOU Thr: 0.5 | 47 |
Soft-NMS | 0.5616 | Sigma: 0.1, Confidence Thr: 0.001 | 88 |
NMW | 0.5667 | IOU Thr: 0.5 | 171 |
WBF | 0.5982 | IOU Thr: 0.6 | 249 |
You can download model predictions as well as ground truth labels from here: test_data.zip
Ensemble script for them is available here: example_oid.py
We also published large benchmark based on COCO dataset here.
Description of WBF method and citation
- https://arxiv.org/abs/1910.13302 (updated: 2020.08)
- https://authors.elsevier.com/c/1ca0dxnVK3cWY
If you find this code useful please cite:
@article{solovyev2021weighted,
title={Weighted boxes fusion: Ensembling boxes from different object detection models},
author={Solovyev, Roman and Wang, Weimin and Gabruseva, Tatiana},
journal={Image and Vision Computing},
pages={1-6},
year={2021},
publisher={Elsevier}
}