Adjust clamping for rotated bboxes

[AntoineSimoulin]

Adjust clamping for Rotated Boxes

This PR is a follow-up for #9104 and slightly adjust some inconsistency in the clamping function. This PR implements in particular the following modifications :

• Modify the conditions from the clamping function to ensure the resulting box completely encapsulate the input box. The output from the clamping operation is the box of smallest area completely overlapping the intersection polygon between the input box and the canvas (and preserving the input box rotation angle).
• With this adjustments, clamped rotated boxes can have vertices outside of the canvas. However, the center of the bounding box is guaranteed to be within the canvas.
• This PR should address Allow bounding boxes transforms to *not* clamp #8254 as we now SHOULD clamp rotated bounding boxes (similar to what is done for un-rotated boxes). The operation should not impact the information captured by the box.

Details on the clamping function

We illustrate the adjustments on the clamping function using this image example. The clamping should be more intuitive and should prevent from loosing information.

Before:

After:

Test plan

Please run the following tests:

pytest test/test_transforms_v2.py -k box -v
...
2372 passed, 1432 skipped, 5025 deselected in 46.08s

[pytorch-bot]

🔗 Helpful Links

🧪 See artifacts and rendered test results at hud.pytorch.org/pr/pytorch/vision/9112

• 📄 Preview Python docs built from this PR

Note: Links to docs will display an error until the docs builds have been completed.

❌ 1 New Failure

As of commit 4261ed3 with merge base d5df0d6 ():

NEW FAILURE - The following job has failed:

• CMake / windows (windows.g5.4xlarge.nvidia.gpu, cuda, 11.8) / windows-job (gh)
  Process completed with exit code 1.

This comment was automatically generated by Dr. CI and updates every 15 minutes.