目标检测中的mAP是什么含义？ - 知乎用户的回答 - 知乎
mAP定义及相关概念
- mAP: mean Average Precision, 即各类别AP的平均值
- AP: PR曲线下面积，后文会详细讲解
- PR曲线: Precision-Recall曲线
- Precision: TP / (TP + FP)
- Recall: TP / (TP + FN)
- TP: IoU>0.5的检测框数量（同一Ground Truth只计算一次）
- FP: IoU<=0.5的检测框，或者是检测到同一个GT的多余检测框的数量
- FN: 没有检测到的GT的数量
链接（github）：Metrics for object detection
Intersection Over Union (IOU)：
True Positive, False Positive, False Negative and True Negative：
Some basic concepts used by the metrics:
- True Positive (TP): A correct detection. Detection with IOU ≥ threshold
- False Positive (FP): A wrong detection. Detection with IOU < threshold
- False Negative (FN): A ground truth not detected
- True Negative (TN): Does not apply. It would represent a corrected misdetection. In the object detection task there are many possible bounding boxes that should not be detected within an image. Thus, TN would be all possible bounding boxes that were corrrectly not detected (so many possible boxes within an image). That's why it is not used by the metrics.
threshold: depending on the metric, it is usually set to 50%, 75% or 95%.
Precision ：
找得对！在你认为的正样本中， 实际是正样本的比例
Recall：
找得全！在真正的正样本中， 有多少被你找到了。
PR曲线：
找得又对又全！Precision × Recall curve
AP：
Average Precision：PR曲线下的面积
mAP：
算均值：所有类别的AP和/总的类别数目