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# Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved | |
import torch | |
from torch import nn | |
from detectron2.config import CfgNode | |
from detectron2.layers import ConvTranspose2d, interpolate | |
from ...structures import DensePoseEmbeddingPredictorOutput | |
from ..utils import initialize_module_params | |
from .registry import DENSEPOSE_PREDICTOR_REGISTRY | |
class DensePoseEmbeddingPredictor(nn.Module): | |
""" | |
Last layers of a DensePose model that take DensePose head outputs as an input | |
and produce model outputs for continuous surface embeddings (CSE). | |
""" | |
def __init__(self, cfg: CfgNode, input_channels: int): | |
""" | |
Initialize predictor using configuration options | |
Args: | |
cfg (CfgNode): configuration options | |
input_channels (int): input tensor size along the channel dimension | |
""" | |
super().__init__() | |
dim_in = input_channels | |
n_segm_chan = cfg.MODEL.ROI_DENSEPOSE_HEAD.NUM_COARSE_SEGM_CHANNELS | |
embed_size = cfg.MODEL.ROI_DENSEPOSE_HEAD.CSE.EMBED_SIZE | |
kernel_size = cfg.MODEL.ROI_DENSEPOSE_HEAD.DECONV_KERNEL | |
# coarse segmentation | |
self.coarse_segm_lowres = ConvTranspose2d( | |
dim_in, n_segm_chan, kernel_size, stride=2, padding=int(kernel_size / 2 - 1) | |
) | |
# embedding | |
self.embed_lowres = ConvTranspose2d( | |
dim_in, embed_size, kernel_size, stride=2, padding=int(kernel_size / 2 - 1) | |
) | |
self.scale_factor = cfg.MODEL.ROI_DENSEPOSE_HEAD.UP_SCALE | |
initialize_module_params(self) | |
def interp2d(self, tensor_nchw: torch.Tensor): | |
""" | |
Bilinear interpolation method to be used for upscaling | |
Args: | |
tensor_nchw (tensor): tensor of shape (N, C, H, W) | |
Return: | |
tensor of shape (N, C, Hout, Wout), where Hout and Wout are computed | |
by applying the scale factor to H and W | |
""" | |
return interpolate( | |
tensor_nchw, scale_factor=self.scale_factor, mode="bilinear", align_corners=False | |
) | |
def forward(self, head_outputs): | |
""" | |
Perform forward step on DensePose head outputs | |
Args: | |
head_outputs (tensor): DensePose head outputs, tensor of shape [N, D, H, W] | |
""" | |
embed_lowres = self.embed_lowres(head_outputs) | |
coarse_segm_lowres = self.coarse_segm_lowres(head_outputs) | |
embed = self.interp2d(embed_lowres) | |
coarse_segm = self.interp2d(coarse_segm_lowres) | |
return DensePoseEmbeddingPredictorOutput(embedding=embed, coarse_segm=coarse_segm) | |