detectron2/configs/Detectron1-Comparisons/README.md

Detectron2 model zoo's experimental settings and a few implementation details are different from Detectron.

The differences in implementation details are shared in Compatibility with Other Libraries.

The differences in model zoo's experimental settings include:

• Use scale augmentation during training. This improves AP with lower training cost.
• Use L1 loss instead of smooth L1 loss for simplicity. This sometimes improves box AP but may affect other AP.
• Use POOLER_SAMPLING_RATIO=0 instead of 2. This does not significantly affect AP.
• Use ROIAlignV2. This does not significantly affect AP.

In this directory, we provide a few configs that do not have the above changes. They mimic Detectron's behavior as close as possible, and provide a fair comparison of accuracy and speed against Detectron.

Name	lr sched	train time (s/iter)	inference time (s/im)	train mem (GB)	box AP	mask AP	kp. AP	model id	download
Faster R-CNN	1x	0.219	0.038	3.1	36.9			137781054	model | metrics
Keypoint R-CNN	1x	0.313	0.071	5.0	53.1		64.2	137781195	model | metrics
Mask R-CNN	1x	0.273	0.043	3.4	37.8	34.9		137781281	model | metrics

Comparisons:

• Faster R-CNN: Detectron's AP is 36.7, similar to ours.
• Keypoint R-CNN: Detectron's AP is box 53.6, keypoint 64.2. Fixing a Detectron's bug lead to a drop in box AP, and can be compensated back by some parameter tuning.
• Mask R-CNN: Detectron's AP is box 37.7, mask 33.9. We're 1 AP better in mask AP, due to more correct implementation. See this article for details.

For speed comparison, see benchmarks.