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