def __init__(self, cfg, box_coder): self.cfg = cfg self.cls_loss_func = SigmoidFocalLoss(cfg.MODEL.ATSS.LOSS_GAMMA, cfg.MODEL.ATSS.LOSS_ALPHA) self.centerness_loss_func = nn.BCEWithLogitsLoss(reduction="sum") self.matcher = Matcher(cfg.MODEL.ATSS.FG_IOU_THRESHOLD, cfg.MODEL.ATSS.BG_IOU_THRESHOLD, True) self.box_coder = box_coder