IOU、mAP等
https://www.zhihu.com/question/53405779/answer/394311144
SPPNet
https://blog.csdn.net/yzf0011/article/details/75212513
http://www.mamicode.com/info-detail-2222982.html
https://blog.csdn.net/u012938704/article/details/71185126
原始图片中的ROI如何映射到到feature map?
https://zhuanlan.zhihu.com/p/24780433
ROI Pooling层详解
https://blog.csdn.net/auto1993/article/details/78514071
faster-rcnn 之 RPN网络的结构解析
https://blog.csdn.net/sloanqin/article/details/51545125
R-FCN论文阅读（R-FCN: Object Detection via Region-based Fully Convolutional Networks ）
https://blog.csdn.net/baidu_32173921/article/details/71741970
