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# Copyright (c) Facebook, Inc. and its affiliates. | |
""" | |
MIT License | |
Copyright (c) 2019 Microsoft | |
Permission is hereby granted, free of charge, to any person obtaining a copy | |
of this software and associated documentation files (the "Software"), to deal | |
in the Software without restriction, including without limitation the rights | |
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell | |
copies of the Software, and to permit persons to whom the Software is | |
furnished to do so, subject to the following conditions: | |
The above copyright notice and this permission notice shall be included in all | |
copies or substantial portions of the Software. | |
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR | |
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, | |
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE | |
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER | |
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, | |
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE | |
SOFTWARE. | |
""" | |
import torch | |
import torch.nn as nn | |
import torch.nn.functional as F | |
from detectron2.layers import ShapeSpec | |
from detectron2.modeling.backbone import BACKBONE_REGISTRY | |
from detectron2.modeling.backbone.backbone import Backbone | |
from .hrnet import build_pose_hrnet_backbone | |
class HRFPN(Backbone): | |
"""HRFPN (High Resolution Feature Pyramids) | |
Transforms outputs of HRNet backbone so they are suitable for the ROI_heads | |
arXiv: https://arxiv.org/abs/1904.04514 | |
Adapted from https://github.com/open-mmlab/mmdetection/blob/master/mmdet/models/necks/hrfpn.py | |
Args: | |
bottom_up: (list) output of HRNet | |
in_features (list): names of the input features (output of HRNet) | |
in_channels (list): number of channels for each branch | |
out_channels (int): output channels of feature pyramids | |
n_out_features (int): number of output stages | |
pooling (str): pooling for generating feature pyramids (from {MAX, AVG}) | |
share_conv (bool): Have one conv per output, or share one with all the outputs | |
""" | |
def __init__( | |
self, | |
bottom_up, | |
in_features, | |
n_out_features, | |
in_channels, | |
out_channels, | |
pooling="AVG", | |
share_conv=False, | |
): | |
super(HRFPN, self).__init__() | |
assert isinstance(in_channels, list) | |
self.bottom_up = bottom_up | |
self.in_features = in_features | |
self.n_out_features = n_out_features | |
self.in_channels = in_channels | |
self.out_channels = out_channels | |
self.num_ins = len(in_channels) | |
self.share_conv = share_conv | |
if self.share_conv: | |
self.fpn_conv = nn.Conv2d( | |
in_channels=out_channels, out_channels=out_channels, kernel_size=3, padding=1 | |
) | |
else: | |
self.fpn_conv = nn.ModuleList() | |
for _ in range(self.n_out_features): | |
self.fpn_conv.append( | |
nn.Conv2d( | |
in_channels=out_channels, | |
out_channels=out_channels, | |
kernel_size=3, | |
padding=1, | |
) | |
) | |
# Custom change: Replaces a simple bilinear interpolation | |
self.interp_conv = nn.ModuleList() | |
for i in range(len(self.in_features)): | |
self.interp_conv.append( | |
nn.Sequential( | |
nn.ConvTranspose2d( | |
in_channels=in_channels[i], | |
out_channels=in_channels[i], | |
kernel_size=4, | |
stride=2**i, | |
padding=0, | |
output_padding=0, | |
bias=False, | |
), | |
nn.BatchNorm2d(in_channels[i], momentum=0.1), | |
nn.ReLU(inplace=True), | |
) | |
) | |
# Custom change: Replaces a couple (reduction conv + pooling) by one conv | |
self.reduction_pooling_conv = nn.ModuleList() | |
for i in range(self.n_out_features): | |
self.reduction_pooling_conv.append( | |
nn.Sequential( | |
nn.Conv2d(sum(in_channels), out_channels, kernel_size=2**i, stride=2**i), | |
nn.BatchNorm2d(out_channels, momentum=0.1), | |
nn.ReLU(inplace=True), | |
) | |
) | |
if pooling == "MAX": | |
self.pooling = F.max_pool2d | |
else: | |
self.pooling = F.avg_pool2d | |
self._out_features = [] | |
self._out_feature_channels = {} | |
self._out_feature_strides = {} | |
for i in range(self.n_out_features): | |
self._out_features.append("p%d" % (i + 1)) | |
self._out_feature_channels.update({self._out_features[-1]: self.out_channels}) | |
self._out_feature_strides.update({self._out_features[-1]: 2 ** (i + 2)}) | |
# default init_weights for conv(msra) and norm in ConvModule | |
def init_weights(self): | |
for m in self.modules(): | |
if isinstance(m, nn.Conv2d): | |
nn.init.kaiming_normal_(m.weight, a=1) | |
nn.init.constant_(m.bias, 0) | |
def forward(self, inputs): | |
bottom_up_features = self.bottom_up(inputs) | |
assert len(bottom_up_features) == len(self.in_features) | |
inputs = [bottom_up_features[f] for f in self.in_features] | |
outs = [] | |
for i in range(len(inputs)): | |
outs.append(self.interp_conv[i](inputs[i])) | |
shape_2 = min(o.shape[2] for o in outs) | |
shape_3 = min(o.shape[3] for o in outs) | |
out = torch.cat([o[:, :, :shape_2, :shape_3] for o in outs], dim=1) | |
outs = [] | |
for i in range(self.n_out_features): | |
outs.append(self.reduction_pooling_conv[i](out)) | |
for i in range(len(outs)): # Make shapes consistent | |
outs[-1 - i] = outs[-1 - i][ | |
:, :, : outs[-1].shape[2] * 2**i, : outs[-1].shape[3] * 2**i | |
] | |
outputs = [] | |
for i in range(len(outs)): | |
if self.share_conv: | |
outputs.append(self.fpn_conv(outs[i])) | |
else: | |
outputs.append(self.fpn_conv[i](outs[i])) | |
assert len(self._out_features) == len(outputs) | |
return dict(zip(self._out_features, outputs)) | |
def build_hrfpn_backbone(cfg, input_shape: ShapeSpec) -> HRFPN: | |
in_channels = cfg.MODEL.HRNET.STAGE4.NUM_CHANNELS | |
in_features = ["p%d" % (i + 1) for i in range(cfg.MODEL.HRNET.STAGE4.NUM_BRANCHES)] | |
n_out_features = len(cfg.MODEL.ROI_HEADS.IN_FEATURES) | |
out_channels = cfg.MODEL.HRNET.HRFPN.OUT_CHANNELS | |
hrnet = build_pose_hrnet_backbone(cfg, input_shape) | |
hrfpn = HRFPN( | |
hrnet, | |
in_features, | |
n_out_features, | |
in_channels, | |
out_channels, | |
pooling="AVG", | |
share_conv=False, | |
) | |
return hrfpn | |