import torch
from mmdet.core import multi_apply
from ..builder import HEADS
from ..losses import CrossEntropyLoss, SmoothL1Loss, carl_loss, isr_p
from .ssd_head import SSDHead
# TODO: add loss evaluator for SSD
[docs]@HEADS.register_module()
class PISASSDHead(SSDHead):
[docs] def loss(self,
cls_scores,
bbox_preds,
gt_bboxes,
gt_labels,
img_metas,
gt_bboxes_ignore=None):
"""Compute losses of the head.
Args:
cls_scores (list[Tensor]): Box scores for each scale level
Has shape (N, num_anchors * num_classes, H, W)
bbox_preds (list[Tensor]): Box energies / deltas for each scale
level with shape (N, num_anchors * 4, H, W)
gt_bboxes (list[Tensor]): Ground truth bboxes of each image
with shape (num_obj, 4).
gt_labels (list[Tensor]): Ground truth labels of each image
with shape (num_obj, 4).
img_metas (list[dict]): Meta information of each image, e.g.,
image size, scaling factor, etc.
gt_bboxes_ignore (list[Tensor]): Ignored gt bboxes of each image.
Default: None.
Returns:
dict: Loss dict, comprise classification loss regression loss and
carl loss.
"""
featmap_sizes = [featmap.size()[-2:] for featmap in cls_scores]
assert len(featmap_sizes) == self.anchor_generator.num_levels
device = cls_scores[0].device
anchor_list, valid_flag_list = self.get_anchors(
featmap_sizes, img_metas, device=device)
cls_reg_targets = self.get_targets(
anchor_list,
valid_flag_list,
gt_bboxes,
img_metas,
gt_bboxes_ignore_list=gt_bboxes_ignore,
gt_labels_list=gt_labels,
label_channels=1,
unmap_outputs=False,
return_sampling_results=True)
if cls_reg_targets is None:
return None
(labels_list, label_weights_list, bbox_targets_list, bbox_weights_list,
num_total_pos, num_total_neg, sampling_results_list) = cls_reg_targets
num_images = len(img_metas)
all_cls_scores = torch.cat([
s.permute(0, 2, 3, 1).reshape(
num_images, -1, self.cls_out_channels) for s in cls_scores
], 1)
all_labels = torch.cat(labels_list, -1).view(num_images, -1)
all_label_weights = torch.cat(label_weights_list,
-1).view(num_images, -1)
all_bbox_preds = torch.cat([
b.permute(0, 2, 3, 1).reshape(num_images, -1, 4)
for b in bbox_preds
], -2)
all_bbox_targets = torch.cat(bbox_targets_list,
-2).view(num_images, -1, 4)
all_bbox_weights = torch.cat(bbox_weights_list,
-2).view(num_images, -1, 4)
# concat all level anchors to a single tensor
all_anchors = []
for i in range(num_images):
all_anchors.append(torch.cat(anchor_list[i]))
isr_cfg = self.train_cfg.get('isr', None)
all_targets = (all_labels.view(-1), all_label_weights.view(-1),
all_bbox_targets.view(-1,
4), all_bbox_weights.view(-1, 4))
# apply ISR-P
if isr_cfg is not None:
all_targets = isr_p(
all_cls_scores.view(-1, all_cls_scores.size(-1)),
all_bbox_preds.view(-1, 4),
all_targets,
torch.cat(all_anchors),
sampling_results_list,
loss_cls=CrossEntropyLoss(),
bbox_coder=self.bbox_coder,
**self.train_cfg.isr,
num_class=self.num_classes)
(new_labels, new_label_weights, new_bbox_targets,
new_bbox_weights) = all_targets
all_labels = new_labels.view(all_labels.shape)
all_label_weights = new_label_weights.view(all_label_weights.shape)
all_bbox_targets = new_bbox_targets.view(all_bbox_targets.shape)
all_bbox_weights = new_bbox_weights.view(all_bbox_weights.shape)
# add CARL loss
carl_loss_cfg = self.train_cfg.get('carl', None)
if carl_loss_cfg is not None:
loss_carl = carl_loss(
all_cls_scores.view(-1, all_cls_scores.size(-1)),
all_targets[0],
all_bbox_preds.view(-1, 4),
all_targets[2],
SmoothL1Loss(beta=1.),
**self.train_cfg.carl,
avg_factor=num_total_pos,
num_class=self.num_classes)
# check NaN and Inf
assert torch.isfinite(all_cls_scores).all().item(), \
'classification scores become infinite or NaN!'
assert torch.isfinite(all_bbox_preds).all().item(), \
'bbox predications become infinite or NaN!'
losses_cls, losses_bbox = multi_apply(
self.loss_single,
all_cls_scores,
all_bbox_preds,
all_anchors,
all_labels,
all_label_weights,
all_bbox_targets,
all_bbox_weights,
num_total_samples=num_total_pos)
loss_dict = dict(loss_cls=losses_cls, loss_bbox=losses_bbox)
if carl_loss_cfg is not None:
loss_dict.update(loss_carl)
return loss_dict