I’m running Faster R-CNN based on (https://github.com/ruotianluo/pytorch-faster-rcnn 4). The loss is a sum over the RPN and Fast RCNN losses, which include 2 L1 smooth loss functions for bbox regression and 2 cross-entropy loss functions for classification (see here 1).
I’m trying to reproduce the error on a small snippet, but haven’t had any luck thus far. I did find, however, that I can call backward on the rpn losses only. The error above is thrown when trying to call backward on the RCNN cross-entropy and bbox losses.