[Feature] Class agnostic NMS for object detector in torch2onnx

[darrenjkt]

Motivation

Currently, overlapping detections of a different class are not filtered out by NMS when converting the mmdetection model to onnx. The class_agnostic flag in the mmdetection model config does not seem to work. I would like to be able to apply a class_agnostic NMS to the output of my detector.

Currently, for RTMDet I have set my model.test_cfg to the following but the class_agnostic flag does not seem to be working (according to my visualized predictions).

{'max_per_img': 300, 'min_bbox_size': 0, 'nms': {'iou_threshold': 0.01, 'type': 'nms', 'class_agnostic': True}, 'nms_pre': 30000, 'score_thr': 0.001}

I've done some digging but I'm not sure where the NMS is currently being encoded into the onnx model so I apologize if this is an implemented feature that I've missed.

Related resources

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Additional context

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