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What does mask r-cnn's AP, AP50, AP70 mean?

I'm novice on r-cnn.

There are term AP, AP50, AP75 on mask r-cnn paper. 50, 75 is small postfix, but I can't make it small, sorry. Anyway the paper says it is averaged over IOU thresholds. For AP50, only candidates over 50% region comparing ground truth are counted, and for AP75 only candidate over 75% are counted. Then what is empty AP? I knew AP use 70% IoU threshold, but it wouldn't. Because just AP is lower then AP75.

And additionally, there are another terms I don't understand well. They are APs, m, L. I know they mean small, medium, large. Then is there any criteria how big they are. Just saying small, medium, large makes me little bit confused.

Thanks in advance!

like image 931
semenbari Avatar asked Jan 26 '18 07:01

semenbari


1 Answers

I found them from below: http://cocodataset.org/#detections-eval

Average Precision (AP):
AP % AP at IoU=.50:.05:.95 (primary challenge metric)
APIoU=.50 % AP at IoU=.50 (PASCAL VOC metric)
APIoU=.75 % AP at IoU=.75 (strict metric)
AP Across Scales: APsmall % AP for small objects: area < 322
APmedium % AP for medium objects: 322 < area < 962
APlarge % AP for large objects: area > 962
Average Recall (AR):
ARmax=1 % AR given 1 detection per image
ARmax=10 % AR given 10 detections per image
ARmax=100 % AR given 100 detections per image
AR Across Scales:
ARsmall % AR for small objects: area < 322
ARmedium % AR for medium objects: 322 < area < 962
ARlarge % AR for large objects: area > 962

Thanks.

like image 56
semenbari Avatar answered Nov 07 '22 20:11

semenbari