Assign anchor parameter & augmentation about cascade-rcnn

[GuoxingYan]

我建议你可以看一下detection_data_layer.cpp，ignore_fg_threshold就是训练的时候用到了。在这个里面有很多值得学习的东西，比如说anchor_ignore_margin_ratio()等等。
至于base的话，我看了作者的fpn base和普通的fpn不一样的很，作者这里都有些想panet的感觉了，感兴趣的话可以看我博客https://mp.csdn.net/postedit/80854160

[zhaoweicai]

fg_threshold is used for assigning labels for anchors. When the image has ignored region, the anchors will be ignored if they have IoU with ignored region that >= ignore_fg_threshold. Removing image distortion won't impair the performance.