本文是結論，詳細過程參考 https://blog.csdn.net/yinglang19941010/article/details/102790168
問題描述
使用Pascal的coco格式標註文件是Detectron代碼提供的，下載地址爲https://github.com/facebookresearch/Detectron/blob/master/detectron/datasets/data/README.md#coco-minival-annotations
使用coco評測標準測出的AP50和voc評測標準測出的AP50不一致，相差好幾個點(4~5).
問題解決
修改評測代碼maskrcnn_benchmark/data/datasets/evaluation/coco/cocoeval.py _prepare函數
# orgin code
# gt['ignore'] = 'iscrowd' in gt and gt['iscrowd']
# changed code
gt['ignore'] = gt['ignore'] if 'ignore' in gt else 0
gt['ignore'] = ('iscrowd' in gt and gt['iscrowd']) or gt['ignore'] # changed by hui
問題簡單分析
Pascal的coco格式標註文件是Detectron代碼提供的，下載地址爲https://github.com/facebookresearch/Detectron/blob/master/detectron/datasets/data/README.md#coco-minival-annotations
加載查看annotations字段，發現他有一個ignore字段，估計應該是pascal裏的difficult字段之類的
In [2]: import json
In [3]: jd_gt = json.load(open('pascal_test2007.json'))
In [4]: jd_gt['annotations'][0]
Out[4]:
{'segmentation': [[47, 239, 47, 371, 195, 371, 195, 239]],
'area': 19536,
'iscrowd': 0,
'image_id': 1,
'bbox': [47, 239, 148, 132],
'category_id': 12,
'id': 1,
'ignore': 0}
但是標準的coco評測代碼裏並沒有ignroe字段，因此，即使ignore不爲0,也不會被處理，但是Pascal VOC中正好有ignore不爲0的數據．
print(len(jd_gt['annotations']))
ann_gt1 = [a for a in jd_gt['annotations'] if a['iscrowd']==0]
print(len(ann_gt1))
ann_gt2 = [a for a in jd_gt['annotations'] if a['ignore']==0]
print(len(ann_gt2))
Out[]:
14976
14976
12032
因此會有這個問題，即使使用ground-truth作爲檢測結果AP也只有80%
