Result mismatch in coco metrics

[purvang3]

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• I have searched the YOLOv5 issues and found no similar bug report.

YOLOv5 Component

Validation

Bug

I see results are not same for mAP@0.50 and mAP@0.50:0.95 during training after each epoch. I have made changes in val.py
accordingly as I am using "xywh" format for bboxes.

I have commented line
#box[:, :2] -= box[:, 2:] / 2 # xy center to top-left corner as my gt in xywh format.

Environment

YOLOv5 🚀 v6.0-144-gc9a46a6 torch 1.10.2 CUDA:0 (NVIDIA RTX A4000, 16116MiB)
os : Ubuntu 18.04

Minimal Reproducible Example

make save_json in val.run=True and start training.

Additional

No response

Are you willing to submit a PR?

• Yes I'd like to help by submitting a PR!

[github-actions]

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[glenn-jocher]

@purvang3 yes mAP mismatch with pycocotools is a known issue, and there's actually an open competition to solve it in #2258

We also have a few PRs related to mAP updates from users that you could try:

• Bug fix mAP0.5-0.95 #6787
• Fix mAP bug at a higher conf #6813

[codingonion]

@purvang3 yes mAP mismatch with pycocotools is a known issue, and there's actually an open competition to solve it in #2258

We also have a few PRs related to mAP updates from users that you could try:

* [Improve mAP0.5-0.95 #6787](https://github.com/ultralytics/yolov5/pull/6787)

* [Fix mAP bug at a higher conf #6813](https://github.com/ultralytics/yolov5/pull/6813)

I had the same problem.
test.py in v4.0、v5.0 is OK.
val.py in v6.0、v6.1 is not OK.
Please see blow.

[glenn-jocher]

@dotnet-rs-py we have a warning in place to advise users of incorrect settings. mAP should be calculated at --conf 0.0 for best results, we compute at --conf 0.001 for significant speed improvements at near identical results. Anything above that will not allow for a full integration of the PR curve from 0 to 1, which will result in incorrect mAP.

yolov5/val.py

Lines 352 to 353 in 99de551

	if opt.conf_thres > 0.001: # https://github.com/ultralytics/yolov5/issues/1466
	LOGGER.info(f'WARNING: confidence threshold {opt.conf_thres} >> 0.001 will produce invalid mAP values.')

[github-actions]

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