Fix batched_nms for rotated box and add type hint for nms.py

[liuyanyi]

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Motivation

When set class_agnostic=False in batched_nms, it will add an offset to det boxes, for horizional bbox in xyxy, the code works fine. But in rotated box (x_ctr, y_ctr, w, h, angle), only center point need offset, so I add a branch to solve that.

Add type hint for nms.py. #1948

Modification

• Update mmcv/ops/nms.py
• Update tests/test_ops/test_nms_rotated.py

BC-breaking (Optional)

Does the modification introduce changes that break the backward-compatibility of the downstream repositories?
If so, please describe how it breaks the compatibility and how the downstream projects should modify their code to keep compatibility with this PR.

Use cases (Optional)

If this PR introduces a new feature, it is better to list some use cases here, and update the documentation.

Checklist

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• Bug fixes are covered by unit tests, the case that causes the bug should be added in the unit tests.
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[zhouzaida]

please @zytx121 have a look.

[zhouzaida]

Hi @liuyanyi , it would be better to add a unit test for this modification.

Unit tests can be added at

mmcv/tests/test_ops/test_nms_rotated.py

Line 73 in 70944a2

# test batched_nms with nms_rotated

[liuyanyi]

Hi @liuyanyi , it would be better to add a unit test for this modification.

Unit tests can be added at

mmcv/tests/test_ops/test_nms_rotated.py

Line 73 in 70944a2

# test batched_nms with nms_rotated

Done

[zytx121]

LGMT