mAP50计算与iou_thres的关系

[lqh964165950]

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mAP50计算与iou_thres有什么关系，运行val.py文件时，改变iou_thres为0.5，精度上升了，召回率稍微下降了，这是为什么？

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[UltralyticsAssistant]

👋 Hello @lqh964165950, thank you for your interest in YOLOv5 🚀! The relationship between [email protected] and iou_thres is an important topic in evaluating object detection performance.

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[LZLwoaini]

MAP是所有类别AP的均值，AP由精确率和召回率确定，而IoU 阈值、confidence （置信度）阈值影响精确率和召回率的计算。

[pderrenger]

@LZLwoaini 您提到得很正确，mAP 是所有类别 AP 的均值，而 AP 是由精确率和召回率决定的。运行 val.py 时更改 IoU 阈值会影响精确率与召回率的平衡：提高 IoU 阈值（如 0.5），会倾向于更严格的匹配标准，通常会提高精确率但稍微降低召回率，因为检测框需要更高的重叠度才能被视为正确。您可以根据具体应用需求调整 IoU 阈值以优化结果。更多关于 mAP 和 IoU 的信息，请参考 Ultralytics Glossary: mAP。