Note We use the Faster RCNN framework [33] for its state-of-the-art performance. Faster RCNN is a two-stage model. The first stage is called region proposal network (RPN), which aims at generating class-agnostic object proposals. The second stage is a box classifier, it takes the boxes predicted by RPN and crops feature maps to generate classification predictions and refined bounding box predictions. These two stages share a common feature map generated by a ConvNet, and box classifier has additio...