[Feature] Rotated Bounding Box GIOU

[marcown]

What's the feature?

Hi there!

GIoU is a very common (loss) function for bounding boxes. Is there any way to utilize mmrotate to use it in python? If you give me a good starting point I can also implement it myself.

regards!

Any other context?

Python only solutions are available but slow :(

[Petros626]

mmrotate/configs/rotated_fcos/README.md

Line 41 in b030f38

At this time bbox loss uses horizontal bbox loss such as `IoULoss`, `GIoULoss`.