Question about ROI heads

[vadimkantorov]

1. Do I understand correctly that in practice for existing configs, only ROIWeakRegHead ends up used? (so box_head isn't used)

2. Do I understand correctly that ROI-pooling is done only once and that student models reuse the computed ROI-features?

3. Do I udnerstand correctly that only a single Pooler scale used at both train and test time?

4. How do you handle background class in WSDDN computation? Do you take into account background scores in softmax over classes in classification branch?

Thank you!