NMS in mrcnn during reference stage

hi, guys~ I’m training my own dataset with mrcnn. But when I tested my model, I found some bboxes overlapped with each other like the picture below. I’m really confused about the principle here, shouldn’t the nms have suppressed these boxes after rpn before classification? Thanks a lot for any help!image

Those bboxes are of the same class?

No, they are from different classes, and of course, some of them are bad predictions with relative low scores. :disappointed_relieved: BTY, I’m not sure, are there two nms during reference stage, one for all proposals in rpn, and the other only between the same class after classification or what?