import torch import torch.nn as nn import torch.nn.functional as F from utils.box_ops import bbox2dist, bbox_iou from utils.distributed_utils import get_world_size, is_dist_avail_and_initialized from .matcher import TaskAlignedAssigner class SetCriterion(object): def __init__(self, cfg): # --------------- Basic parameters --------------- self.cfg = cfg self.reg_max = cfg.reg_max self.num_classes = cfg.num_classes # --------------- Loss config --------------- self.loss_cls_weight = cfg.loss_cls self.loss_box_weight = cfg.loss_box self.loss_dfl_weight = cfg.loss_dfl # --------------- Matcher config --------------- self.matcher = TaskAlignedAssigner(num_classes = cfg.num_classes, topk_candidates = cfg.tal_topk_candidates, alpha = cfg.tal_alpha, beta = cfg.tal_beta ) def loss_classes(self, pred_cls, gt_score): # compute bce loss loss_cls = F.binary_cross_entropy_with_logits(pred_cls, gt_score, reduction='none') return loss_cls def loss_bboxes(self, pred_box, gt_box, bbox_weight): # regression loss ious = bbox_iou(pred_box, gt_box, xywh=False, CIoU=True) loss_box = (1.0 - ious.squeeze(-1)) * bbox_weight return loss_box def loss_dfl(self, pred_reg, gt_box, anchor, stride, bbox_weight=None): # rescale coords by stride gt_box_s = gt_box / stride anchor_s = anchor / stride # compute deltas gt_ltrb_s = bbox2dist(anchor_s, gt_box_s, self.reg_max - 1) gt_left = gt_ltrb_s.to(torch.long) gt_right = gt_left + 1 weight_left = gt_right.to(torch.float) - gt_ltrb_s weight_right = 1 - weight_left # loss left loss_left = F.cross_entropy( pred_reg.view(-1, self.reg_max), gt_left.view(-1), reduction='none').view(gt_left.shape) * weight_left # loss right loss_right = F.cross_entropy( pred_reg.view(-1, self.reg_max), gt_right.view(-1), reduction='none').view(gt_left.shape) * weight_right loss_dfl = (loss_left + loss_right).mean(-1) if bbox_weight is not None: loss_dfl *= bbox_weight return loss_dfl def __call__(self, outputs, targets): """ outputs['pred_cls']: List(Tensor) [B, M, C] outputs['pred_reg']: List(Tensor) [B, M, 4*(reg_max+1)] outputs['pred_box']: List(Tensor) [B, M, 4] outputs['anchors']: List(Tensor) [M, 2] outputs['strides']: List(Int) [8, 16, 32] output stride outputs['stride_tensor']: List(Tensor) [M, 1] targets: (List) [dict{'boxes': [...], 'labels': [...], 'orig_size': ...}, ...] """ # preds: [B, M, C] cls_preds = torch.cat(outputs['pred_cls'], dim=1) reg_preds = torch.cat(outputs['pred_reg'], dim=1) box_preds = torch.cat(outputs['pred_box'], dim=1) bs, num_anchors = cls_preds.shape[:2] device = cls_preds.device anchors = torch.cat(outputs['anchors'], dim=0) # --------------- label assignment --------------- gt_score_targets = [] gt_bbox_targets = [] fg_masks = [] for batch_idx in range(bs): tgt_labels = targets[batch_idx]["labels"].to(device) # [Mp,] tgt_boxs = targets[batch_idx]["boxes"].to(device) # [Mp, 4] if self.cfg.normalize_coords: img_h, img_w = outputs['image_size'] tgt_boxs[..., [0, 2]] *= img_w tgt_boxs[..., [1, 3]] *= img_h if self.cfg.box_format == 'xywh': tgt_boxs_x1y1 = tgt_boxs[..., :2] - 0.5 * tgt_boxs[..., 2:] tgt_boxs_x2y2 = tgt_boxs[..., :2] + 0.5 * tgt_boxs[..., 2:] tgt_boxs = torch.cat([tgt_boxs_x1y1, tgt_boxs_x2y2], dim=-1) # check target if len(tgt_labels) == 0 or tgt_boxs.max().item() == 0.: # There is no valid gt fg_mask = cls_preds.new_zeros(1, num_anchors).bool() #[1, M,] gt_score = cls_preds.new_zeros((1, num_anchors, self.num_classes)) #[1, M, C] gt_box = cls_preds.new_zeros((1, num_anchors, 4)) #[1, M, 4] else: tgt_labels = tgt_labels[None, :, None] # [1, Mp, 1] tgt_boxs = tgt_boxs[None] # [1, Mp, 4] ( _, gt_box, # [1, M, 4] gt_score, # [1, M, C] fg_mask, # [1, M,] _ ) = self.matcher( pd_scores = cls_preds[batch_idx:batch_idx+1].detach().sigmoid(), pd_bboxes = box_preds[batch_idx:batch_idx+1].detach(), anc_points = anchors, gt_labels = tgt_labels, gt_bboxes = tgt_boxs ) gt_score_targets.append(gt_score) gt_bbox_targets.append(gt_box) fg_masks.append(fg_mask) # List[B, 1, M, C] -> Tensor[B, M, C] -> Tensor[BM, C] fg_masks = torch.cat(fg_masks, 0).view(-1) # [BM,] gt_score_targets = torch.cat(gt_score_targets, 0).view(-1, self.num_classes) # [BM, C] gt_bbox_targets = torch.cat(gt_bbox_targets, 0).view(-1, 4) # [BM, 4] num_fgs = gt_score_targets.sum() # Average loss normalizer across all the GPUs if is_dist_avail_and_initialized(): torch.distributed.all_reduce(num_fgs) num_fgs = (num_fgs / get_world_size()).clamp(1.0) # ------------------ Classification loss ------------------ cls_preds = cls_preds.view(-1, self.num_classes) loss_cls = self.loss_classes(cls_preds, gt_score_targets) loss_cls = loss_cls.sum() / num_fgs # ------------------ Regression loss ------------------ box_preds_pos = box_preds.view(-1, 4)[fg_masks] box_targets_pos = gt_bbox_targets.view(-1, 4)[fg_masks] bbox_weight = gt_score_targets[fg_masks].sum(-1) loss_box = self.loss_bboxes(box_preds_pos, box_targets_pos, bbox_weight) loss_box = loss_box.sum() / num_fgs # ------------------ Distribution focal loss ------------------ ## process anchors anchors = anchors[None].repeat(bs, 1, 1).view(-1, 2) ## process stride tensors strides = torch.cat(outputs['stride_tensor'], dim=0) strides = strides.unsqueeze(0).repeat(bs, 1, 1).view(-1, 1) ## fg preds reg_preds_pos = reg_preds.view(-1, 4*self.reg_max)[fg_masks] anchors_pos = anchors[fg_masks] strides_pos = strides[fg_masks] ## compute dfl loss_dfl = self.loss_dfl(reg_preds_pos, box_targets_pos, anchors_pos, strides_pos, bbox_weight) loss_dfl = loss_dfl.sum() / num_fgs # total loss losses = loss_cls * self.loss_cls_weight + loss_box * self.loss_box_weight + loss_dfl * self.loss_dfl_weight loss_dict = dict( loss_cls = loss_cls, loss_box = loss_box, loss_dfl = loss_dfl, losses = losses ) return loss_dict if __name__ == "__main__": pass