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# Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved | |
from typing import Any, List | |
import torch | |
from detectron2.config import CfgNode | |
from detectron2.structures import Instances | |
from .mask import MaskLoss | |
from .segm import SegmentationLoss | |
class MaskOrSegmentationLoss: | |
""" | |
Mask or segmentation loss as cross-entropy for raw unnormalized scores | |
given ground truth labels. Ground truth labels are either defined by coarse | |
segmentation annotation, or by mask annotation, depending on the config | |
value MODEL.ROI_DENSEPOSE_HEAD.COARSE_SEGM_TRAINED_BY_MASKS | |
""" | |
def __init__(self, cfg: CfgNode): | |
""" | |
Initialize segmentation loss from configuration options | |
Args: | |
cfg (CfgNode): configuration options | |
""" | |
self.segm_trained_by_masks = cfg.MODEL.ROI_DENSEPOSE_HEAD.COARSE_SEGM_TRAINED_BY_MASKS | |
if self.segm_trained_by_masks: | |
self.mask_loss = MaskLoss() | |
self.segm_loss = SegmentationLoss(cfg) | |
def __call__( | |
self, | |
proposals_with_gt: List[Instances], | |
densepose_predictor_outputs: Any, | |
packed_annotations: Any, | |
) -> torch.Tensor: | |
""" | |
Compute segmentation loss as cross-entropy between aligned unnormalized | |
score estimates and ground truth; with ground truth given | |
either by masks, or by coarse segmentation annotations. | |
Args: | |
proposals_with_gt (list of Instances): detections with associated ground truth data | |
densepose_predictor_outputs: an object of a dataclass that contains predictor outputs | |
with estimated values; assumed to have the following attributes: | |
* coarse_segm - coarse segmentation estimates, tensor of shape [N, D, S, S] | |
packed_annotations: packed annotations for efficient loss computation | |
Return: | |
tensor: loss value as cross-entropy for raw unnormalized scores | |
given ground truth labels | |
""" | |
if self.segm_trained_by_masks: | |
return self.mask_loss(proposals_with_gt, densepose_predictor_outputs) | |
return self.segm_loss(proposals_with_gt, densepose_predictor_outputs, packed_annotations) | |
def fake_value(self, densepose_predictor_outputs: Any) -> torch.Tensor: | |
""" | |
Fake segmentation loss used when no suitable ground truth data | |
was found in a batch. The loss has a value 0 and is primarily used to | |
construct the computation graph, so that `DistributedDataParallel` | |
has similar graphs on all GPUs and can perform reduction properly. | |
Args: | |
densepose_predictor_outputs: DensePose predictor outputs, an object | |
of a dataclass that is assumed to have `coarse_segm` | |
attribute | |
Return: | |
Zero value loss with proper computation graph | |
""" | |
return densepose_predictor_outputs.coarse_segm.sum() * 0 | |