where block back propagate?

[CongWeilin]

for both positive and negative images, we calculate cls_prob and bbox_pred loss, however, do not backward update the bbow_pred weigh for negative images by block back propagate.

I have read the source code, however I could not find where block back propagate.

Where can i find it?

Thanks~

[Seanlinx]

core/negativemining.py, line 25 and line 42 find out the valid indexes for cls and bbox. In backward, only gradient on valid indexes are assigned 1 otherwise 0.