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# Ultralytics YOLO 🚀, AGPL-3.0 license
import torch
import torch.nn as nn
import torch.nn.functional as F
from ultralytics.utils.loss import FocalLoss, VarifocalLoss
from ultralytics.utils.metrics import bbox_iou
from .ops import HungarianMatcher
class DETRLoss(nn.Module):
def __init__(self,
nc=80,
loss_gain=None,
aux_loss=True,
use_fl=True,
use_vfl=False,
use_uni_match=False,
uni_match_ind=0):
"""
DETR loss function.
Args:
nc (int): The number of classes.
loss_gain (dict): The coefficient of loss.
aux_loss (bool): If 'aux_loss = True', loss at each decoder layer are to be used.
use_vfl (bool): Use VarifocalLoss or not.
use_uni_match (bool): Whether to use a fixed layer to assign labels for auxiliary branch.
uni_match_ind (int): The fixed indices of a layer.
"""
super().__init__()
if loss_gain is None:
loss_gain = {'class': 1, 'bbox': 5, 'giou': 2, 'no_object': 0.1, 'mask': 1, 'dice': 1}
self.nc = nc
self.matcher = HungarianMatcher(cost_gain={'class': 2, 'bbox': 5, 'giou': 2})
self.loss_gain = loss_gain
self.aux_loss = aux_loss
self.fl = FocalLoss() if use_fl else None
self.vfl = VarifocalLoss() if use_vfl else None
self.use_uni_match = use_uni_match
self.uni_match_ind = uni_match_ind
self.device = None
def _get_loss_class(self, pred_scores, targets, gt_scores, num_gts, postfix=''):
# logits: [b, query, num_classes], gt_class: list[[n, 1]]
name_class = f'loss_class{postfix}'
bs, nq = pred_scores.shape[:2]
# one_hot = F.one_hot(targets, self.nc + 1)[..., :-1] # (bs, num_queries, num_classes)
one_hot = torch.zeros((bs, nq, self.nc + 1), dtype=torch.int64, device=targets.device)
one_hot.scatter_(2, targets.unsqueeze(-1), 1)
one_hot = one_hot[..., :-1]
gt_scores = gt_scores.view(bs, nq, 1) * one_hot
if self.fl:
if num_gts and self.vfl:
loss_cls = self.vfl(pred_scores, gt_scores, one_hot)
else:
loss_cls = self.fl(pred_scores, one_hot.float())
loss_cls /= max(num_gts, 1) / nq
else:
loss_cls = nn.BCEWithLogitsLoss(reduction='none')(pred_scores, gt_scores).mean(1).sum() # YOLO CLS loss
return {name_class: loss_cls.squeeze() * self.loss_gain['class']}
def _get_loss_bbox(self, pred_bboxes, gt_bboxes, postfix=''):
# boxes: [b, query, 4], gt_bbox: list[[n, 4]]
name_bbox = f'loss_bbox{postfix}'
name_giou = f'loss_giou{postfix}'
loss = {}
if len(gt_bboxes) == 0:
loss[name_bbox] = torch.tensor(0., device=self.device)
loss[name_giou] = torch.tensor(0., device=self.device)
return loss
loss[name_bbox] = self.loss_gain['bbox'] * F.l1_loss(pred_bboxes, gt_bboxes, reduction='sum') / len(gt_bboxes)
loss[name_giou] = 1.0 - bbox_iou(pred_bboxes, gt_bboxes, xywh=True, GIoU=True)
loss[name_giou] = loss[name_giou].sum() / len(gt_bboxes)
loss[name_giou] = self.loss_gain['giou'] * loss[name_giou]
return {k: v.squeeze() for k, v in loss.items()}
def _get_loss_mask(self, masks, gt_mask, match_indices, postfix=''):
# masks: [b, query, h, w], gt_mask: list[[n, H, W]]
name_mask = f'loss_mask{postfix}'
name_dice = f'loss_dice{postfix}'
loss = {}
if sum(len(a) for a in gt_mask) == 0:
loss[name_mask] = torch.tensor(0., device=self.device)
loss[name_dice] = torch.tensor(0., device=self.device)
return loss
num_gts = len(gt_mask)
src_masks, target_masks = self._get_assigned_bboxes(masks, gt_mask, match_indices)
src_masks = F.interpolate(src_masks.unsqueeze(0), size=target_masks.shape[-2:], mode='bilinear')[0]
# TODO: torch does not have `sigmoid_focal_loss`, but it's not urgent since we don't use mask branch for now.
loss[name_mask] = self.loss_gain['mask'] * F.sigmoid_focal_loss(src_masks, target_masks,
torch.tensor([num_gts], dtype=torch.float32))
loss[name_dice] = self.loss_gain['dice'] * self._dice_loss(src_masks, target_masks, num_gts)
return loss
@staticmethod
def _dice_loss(inputs, targets, num_gts):
inputs = F.sigmoid(inputs)
inputs = inputs.flatten(1)
targets = targets.flatten(1)
numerator = 2 * (inputs * targets).sum(1)
denominator = inputs.sum(-1) + targets.sum(-1)
loss = 1 - (numerator + 1) / (denominator + 1)
return loss.sum() / num_gts
def _get_loss_aux(self,
pred_bboxes,
pred_scores,
gt_bboxes,
gt_cls,
gt_groups,
match_indices=None,
postfix='',
masks=None,
gt_mask=None):
"""Get auxiliary losses"""
# NOTE: loss class, bbox, giou, mask, dice
loss = torch.zeros(5 if masks is not None else 3, device=pred_bboxes.device)
if match_indices is None and self.use_uni_match:
match_indices = self.matcher(pred_bboxes[self.uni_match_ind],
pred_scores[self.uni_match_ind],
gt_bboxes,
gt_cls,
gt_groups,
masks=masks[self.uni_match_ind] if masks is not None else None,
gt_mask=gt_mask)
for i, (aux_bboxes, aux_scores) in enumerate(zip(pred_bboxes, pred_scores)):
aux_masks = masks[i] if masks is not None else None
loss_ = self._get_loss(aux_bboxes,
aux_scores,
gt_bboxes,
gt_cls,
gt_groups,
masks=aux_masks,
gt_mask=gt_mask,
postfix=postfix,
match_indices=match_indices)
loss[0] += loss_[f'loss_class{postfix}']
loss[1] += loss_[f'loss_bbox{postfix}']
loss[2] += loss_[f'loss_giou{postfix}']
# if masks is not None and gt_mask is not None:
# loss_ = self._get_loss_mask(aux_masks, gt_mask, match_indices, postfix)
# loss[3] += loss_[f'loss_mask{postfix}']
# loss[4] += loss_[f'loss_dice{postfix}']
loss = {
f'loss_class_aux{postfix}': loss[0],
f'loss_bbox_aux{postfix}': loss[1],
f'loss_giou_aux{postfix}': loss[2]}
# if masks is not None and gt_mask is not None:
# loss[f'loss_mask_aux{postfix}'] = loss[3]
# loss[f'loss_dice_aux{postfix}'] = loss[4]
return loss
@staticmethod
def _get_index(match_indices):
batch_idx = torch.cat([torch.full_like(src, i) for i, (src, _) in enumerate(match_indices)])
src_idx = torch.cat([src for (src, _) in match_indices])
dst_idx = torch.cat([dst for (_, dst) in match_indices])
return (batch_idx, src_idx), dst_idx
def _get_assigned_bboxes(self, pred_bboxes, gt_bboxes, match_indices):
pred_assigned = torch.cat([
t[I] if len(I) > 0 else torch.zeros(0, t.shape[-1], device=self.device)
for t, (I, _) in zip(pred_bboxes, match_indices)])
gt_assigned = torch.cat([
t[J] if len(J) > 0 else torch.zeros(0, t.shape[-1], device=self.device)
for t, (_, J) in zip(gt_bboxes, match_indices)])
return pred_assigned, gt_assigned
def _get_loss(self,
pred_bboxes,
pred_scores,
gt_bboxes,
gt_cls,
gt_groups,
masks=None,
gt_mask=None,
postfix='',
match_indices=None):
"""Get losses"""
if match_indices is None:
match_indices = self.matcher(pred_bboxes,
pred_scores,
gt_bboxes,
gt_cls,
gt_groups,
masks=masks,
gt_mask=gt_mask)
idx, gt_idx = self._get_index(match_indices)
pred_bboxes, gt_bboxes = pred_bboxes[idx], gt_bboxes[gt_idx]
bs, nq = pred_scores.shape[:2]
targets = torch.full((bs, nq), self.nc, device=pred_scores.device, dtype=gt_cls.dtype)
targets[idx] = gt_cls[gt_idx]
gt_scores = torch.zeros([bs, nq], device=pred_scores.device)
if len(gt_bboxes):
gt_scores[idx] = bbox_iou(pred_bboxes.detach(), gt_bboxes, xywh=True).squeeze(-1)
loss = {}
loss.update(self._get_loss_class(pred_scores, targets, gt_scores, len(gt_bboxes), postfix))
loss.update(self._get_loss_bbox(pred_bboxes, gt_bboxes, postfix))
# if masks is not None and gt_mask is not None:
# loss.update(self._get_loss_mask(masks, gt_mask, match_indices, postfix))
return loss
def forward(self, pred_bboxes, pred_scores, batch, postfix='', **kwargs):
"""
Args:
pred_bboxes (torch.Tensor): [l, b, query, 4]
pred_scores (torch.Tensor): [l, b, query, num_classes]
batch (dict): A dict includes:
gt_cls (torch.Tensor) with shape [num_gts, ],
gt_bboxes (torch.Tensor): [num_gts, 4],
gt_groups (List(int)): a list of batch size length includes the number of gts of each image.
postfix (str): postfix of loss name.
"""
self.device = pred_bboxes.device
match_indices = kwargs.get('match_indices', None)
gt_cls, gt_bboxes, gt_groups = batch['cls'], batch['bboxes'], batch['gt_groups']
total_loss = self._get_loss(pred_bboxes[-1],
pred_scores[-1],
gt_bboxes,
gt_cls,
gt_groups,
postfix=postfix,
match_indices=match_indices)
if self.aux_loss:
total_loss.update(
self._get_loss_aux(pred_bboxes[:-1], pred_scores[:-1], gt_bboxes, gt_cls, gt_groups, match_indices,
postfix))
return total_loss
class RTDETRDetectionLoss(DETRLoss):
def forward(self, preds, batch, dn_bboxes=None, dn_scores=None, dn_meta=None):
pred_bboxes, pred_scores = preds
total_loss = super().forward(pred_bboxes, pred_scores, batch)
if dn_meta is not None:
dn_pos_idx, dn_num_group = dn_meta['dn_pos_idx'], dn_meta['dn_num_group']
assert len(batch['gt_groups']) == len(dn_pos_idx)
# Denoising match indices
match_indices = self.get_dn_match_indices(dn_pos_idx, dn_num_group, batch['gt_groups'])
# Compute denoising training loss
dn_loss = super().forward(dn_bboxes, dn_scores, batch, postfix='_dn', match_indices=match_indices)
total_loss.update(dn_loss)
else:
total_loss.update({f'{k}_dn': torch.tensor(0., device=self.device) for k in total_loss.keys()})
return total_loss
@staticmethod
def get_dn_match_indices(dn_pos_idx, dn_num_group, gt_groups):
"""
Get the match indices for denoising.
Args:
dn_pos_idx (List[torch.Tensor]): A list includes positive indices of denoising.
dn_num_group (int): The number of groups of denoising.
gt_groups (List(int)): a list of batch size length includes the number of gts of each image.
Returns:
dn_match_indices (List(tuple)): Matched indices.
"""
dn_match_indices = []
idx_groups = torch.as_tensor([0, *gt_groups[:-1]]).cumsum_(0)
for i, num_gt in enumerate(gt_groups):
if num_gt > 0:
gt_idx = torch.arange(end=num_gt, dtype=torch.long) + idx_groups[i]
gt_idx = gt_idx.repeat(dn_num_group)
assert len(dn_pos_idx[i]) == len(gt_idx), 'Expected the same length, '
f'but got {len(dn_pos_idx[i])} and {len(gt_idx)} respectively.'
dn_match_indices.append((dn_pos_idx[i], gt_idx))
else:
dn_match_indices.append((torch.zeros([0], dtype=torch.long), torch.zeros([0], dtype=torch.long)))
return dn_match_indices
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