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- # Copyright (c) OpenMMLab. All rights reserved.
- import warnings
-
- import torch.nn as nn
- from mmcv.cnn import build_conv_layer, build_norm_layer
- from mmcv.runner import BaseModule, ModuleList, Sequential
- from torch.nn.modules.batchnorm import _BatchNorm
-
- from ..builder import BACKBONES
- from .resnet import BasicBlock, Bottleneck
-
-
- class HRModule(BaseModule):
- """High-Resolution Module for HRNet.
-
- In this module, every branch has 4 BasicBlocks/Bottlenecks. Fusion/Exchange
- is in this module.
- """
-
- def __init__(self,
- num_branches,
- blocks,
- num_blocks,
- in_channels,
- num_channels,
- multiscale_output=True,
- with_cp=False,
- conv_cfg=None,
- norm_cfg=dict(type='BN'),
- block_init_cfg=None,
- init_cfg=None):
- super(HRModule, self).__init__(init_cfg)
- self.block_init_cfg = block_init_cfg
- self._check_branches(num_branches, num_blocks, in_channels,
- num_channels)
-
- self.in_channels = in_channels
- self.num_branches = num_branches
-
- self.multiscale_output = multiscale_output
- self.norm_cfg = norm_cfg
- self.conv_cfg = conv_cfg
- self.with_cp = with_cp
- self.branches = self._make_branches(num_branches, blocks, num_blocks,
- num_channels)
- self.fuse_layers = self._make_fuse_layers()
- self.relu = nn.ReLU(inplace=False)
-
- def _check_branches(self, num_branches, num_blocks, in_channels,
- num_channels):
- if num_branches != len(num_blocks):
- error_msg = f'NUM_BRANCHES({num_branches}) ' \
- f'!= NUM_BLOCKS({len(num_blocks)})'
- raise ValueError(error_msg)
-
- if num_branches != len(num_channels):
- error_msg = f'NUM_BRANCHES({num_branches}) ' \
- f'!= NUM_CHANNELS({len(num_channels)})'
- raise ValueError(error_msg)
-
- if num_branches != len(in_channels):
- error_msg = f'NUM_BRANCHES({num_branches}) ' \
- f'!= NUM_INCHANNELS({len(in_channels)})'
- raise ValueError(error_msg)
-
- def _make_one_branch(self,
- branch_index,
- block,
- num_blocks,
- num_channels,
- stride=1):
- downsample = None
- if stride != 1 or \
- self.in_channels[branch_index] != \
- num_channels[branch_index] * block.expansion:
- downsample = nn.Sequential(
- build_conv_layer(
- self.conv_cfg,
- self.in_channels[branch_index],
- num_channels[branch_index] * block.expansion,
- kernel_size=1,
- stride=stride,
- bias=False),
- build_norm_layer(self.norm_cfg, num_channels[branch_index] *
- block.expansion)[1])
-
- layers = []
- layers.append(
- block(
- self.in_channels[branch_index],
- num_channels[branch_index],
- stride,
- downsample=downsample,
- with_cp=self.with_cp,
- norm_cfg=self.norm_cfg,
- conv_cfg=self.conv_cfg,
- init_cfg=self.block_init_cfg))
- self.in_channels[branch_index] = \
- num_channels[branch_index] * block.expansion
- for i in range(1, num_blocks[branch_index]):
- layers.append(
- block(
- self.in_channels[branch_index],
- num_channels[branch_index],
- with_cp=self.with_cp,
- norm_cfg=self.norm_cfg,
- conv_cfg=self.conv_cfg,
- init_cfg=self.block_init_cfg))
-
- return Sequential(*layers)
-
- def _make_branches(self, num_branches, block, num_blocks, num_channels):
- branches = []
-
- for i in range(num_branches):
- branches.append(
- self._make_one_branch(i, block, num_blocks, num_channels))
-
- return ModuleList(branches)
-
- def _make_fuse_layers(self):
- if self.num_branches == 1:
- return None
-
- num_branches = self.num_branches
- in_channels = self.in_channels
- fuse_layers = []
- num_out_branches = num_branches if self.multiscale_output else 1
- for i in range(num_out_branches):
- fuse_layer = []
- for j in range(num_branches):
- if j > i:
- fuse_layer.append(
- nn.Sequential(
- build_conv_layer(
- self.conv_cfg,
- in_channels[j],
- in_channels[i],
- kernel_size=1,
- stride=1,
- padding=0,
- bias=False),
- build_norm_layer(self.norm_cfg, in_channels[i])[1],
- nn.Upsample(
- scale_factor=2**(j - i), mode='nearest')))
- elif j == i:
- fuse_layer.append(None)
- else:
- conv_downsamples = []
- for k in range(i - j):
- if k == i - j - 1:
- conv_downsamples.append(
- nn.Sequential(
- build_conv_layer(
- self.conv_cfg,
- in_channels[j],
- in_channels[i],
- kernel_size=3,
- stride=2,
- padding=1,
- bias=False),
- build_norm_layer(self.norm_cfg,
- in_channels[i])[1]))
- else:
- conv_downsamples.append(
- nn.Sequential(
- build_conv_layer(
- self.conv_cfg,
- in_channels[j],
- in_channels[j],
- kernel_size=3,
- stride=2,
- padding=1,
- bias=False),
- build_norm_layer(self.norm_cfg,
- in_channels[j])[1],
- nn.ReLU(inplace=False)))
- fuse_layer.append(nn.Sequential(*conv_downsamples))
- fuse_layers.append(nn.ModuleList(fuse_layer))
-
- return nn.ModuleList(fuse_layers)
-
- def forward(self, x):
- """Forward function."""
- if self.num_branches == 1:
- return [self.branches[0](x[0])]
-
- for i in range(self.num_branches):
- x[i] = self.branches[i](x[i])
-
- x_fuse = []
- for i in range(len(self.fuse_layers)):
- y = 0
- for j in range(self.num_branches):
- if i == j:
- y += x[j]
- else:
- y += self.fuse_layers[i][j](x[j])
- x_fuse.append(self.relu(y))
- return x_fuse
-
-
- @BACKBONES.register_module()
- class HRNet(BaseModule):
- """HRNet backbone.
-
- `High-Resolution Representations for Labeling Pixels and Regions
- arXiv: <https://arxiv.org/abs/1904.04514>`_.
-
- Args:
- extra (dict): Detailed configuration for each stage of HRNet.
- There must be 4 stages, the configuration for each stage must have
- 5 keys:
-
- - num_modules(int): The number of HRModule in this stage.
- - num_branches(int): The number of branches in the HRModule.
- - block(str): The type of convolution block.
- - num_blocks(tuple): The number of blocks in each branch.
- The length must be equal to num_branches.
- - num_channels(tuple): The number of channels in each branch.
- The length must be equal to num_branches.
- in_channels (int): Number of input image channels. Default: 3.
- conv_cfg (dict): Dictionary to construct and config conv layer.
- norm_cfg (dict): Dictionary to construct and config norm layer.
- norm_eval (bool): Whether to set norm layers to eval mode, namely,
- freeze running stats (mean and var). Note: Effect on Batch Norm
- and its variants only. Default: True.
- with_cp (bool): Use checkpoint or not. Using checkpoint will save some
- memory while slowing down the training speed. Default: False.
- zero_init_residual (bool): Whether to use zero init for last norm layer
- in resblocks to let them behave as identity. Default: False.
- multiscale_output (bool): Whether to output multi-level features
- produced by multiple branches. If False, only the first level
- feature will be output. Default: True.
- pretrained (str, optional): Model pretrained path. Default: None.
- init_cfg (dict or list[dict], optional): Initialization config dict.
- Default: None.
-
- Example:
- >>> from mmdet.models import HRNet
- >>> import torch
- >>> extra = dict(
- >>> stage1=dict(
- >>> num_modules=1,
- >>> num_branches=1,
- >>> block='BOTTLENECK',
- >>> num_blocks=(4, ),
- >>> num_channels=(64, )),
- >>> stage2=dict(
- >>> num_modules=1,
- >>> num_branches=2,
- >>> block='BASIC',
- >>> num_blocks=(4, 4),
- >>> num_channels=(32, 64)),
- >>> stage3=dict(
- >>> num_modules=4,
- >>> num_branches=3,
- >>> block='BASIC',
- >>> num_blocks=(4, 4, 4),
- >>> num_channels=(32, 64, 128)),
- >>> stage4=dict(
- >>> num_modules=3,
- >>> num_branches=4,
- >>> block='BASIC',
- >>> num_blocks=(4, 4, 4, 4),
- >>> num_channels=(32, 64, 128, 256)))
- >>> self = HRNet(extra, in_channels=1)
- >>> self.eval()
- >>> inputs = torch.rand(1, 1, 32, 32)
- >>> level_outputs = self.forward(inputs)
- >>> for level_out in level_outputs:
- ... print(tuple(level_out.shape))
- (1, 32, 8, 8)
- (1, 64, 4, 4)
- (1, 128, 2, 2)
- (1, 256, 1, 1)
- """
-
- blocks_dict = {'BASIC': BasicBlock, 'BOTTLENECK': Bottleneck}
-
- def __init__(self,
- extra,
- in_channels=3,
- conv_cfg=None,
- norm_cfg=dict(type='BN'),
- norm_eval=True,
- with_cp=False,
- zero_init_residual=False,
- multiscale_output=True,
- pretrained=None,
- init_cfg=None):
- super(HRNet, self).__init__(init_cfg)
-
- self.pretrained = pretrained
- assert not (init_cfg and pretrained), \
- 'init_cfg and pretrained cannot be specified at the same time'
- if isinstance(pretrained, str):
- warnings.warn('DeprecationWarning: pretrained is deprecated, '
- 'please use "init_cfg" instead')
- self.init_cfg = dict(type='Pretrained', checkpoint=pretrained)
- elif pretrained is None:
- if init_cfg is None:
- self.init_cfg = [
- dict(type='Kaiming', layer='Conv2d'),
- dict(
- type='Constant',
- val=1,
- layer=['_BatchNorm', 'GroupNorm'])
- ]
- else:
- raise TypeError('pretrained must be a str or None')
-
- # Assert configurations of 4 stages are in extra
- assert 'stage1' in extra and 'stage2' in extra \
- and 'stage3' in extra and 'stage4' in extra
- # Assert whether the length of `num_blocks` and `num_channels` are
- # equal to `num_branches`
- for i in range(4):
- cfg = extra[f'stage{i + 1}']
- assert len(cfg['num_blocks']) == cfg['num_branches'] and \
- len(cfg['num_channels']) == cfg['num_branches']
-
- self.extra = extra
- self.conv_cfg = conv_cfg
- self.norm_cfg = norm_cfg
- self.norm_eval = norm_eval
- self.with_cp = with_cp
- self.zero_init_residual = zero_init_residual
-
- # stem net
- self.norm1_name, norm1 = build_norm_layer(self.norm_cfg, 64, postfix=1)
- self.norm2_name, norm2 = build_norm_layer(self.norm_cfg, 64, postfix=2)
-
- self.conv1 = build_conv_layer(
- self.conv_cfg,
- in_channels,
- 64,
- kernel_size=3,
- stride=2,
- padding=1,
- bias=False)
-
- self.add_module(self.norm1_name, norm1)
- self.conv2 = build_conv_layer(
- self.conv_cfg,
- 64,
- 64,
- kernel_size=3,
- stride=2,
- padding=1,
- bias=False)
-
- self.add_module(self.norm2_name, norm2)
- self.relu = nn.ReLU(inplace=True)
-
- # stage 1
- self.stage1_cfg = self.extra['stage1']
- num_channels = self.stage1_cfg['num_channels'][0]
- block_type = self.stage1_cfg['block']
- num_blocks = self.stage1_cfg['num_blocks'][0]
-
- block = self.blocks_dict[block_type]
- stage1_out_channels = num_channels * block.expansion
- self.layer1 = self._make_layer(block, 64, num_channels, num_blocks)
-
- # stage 2
- self.stage2_cfg = self.extra['stage2']
- num_channels = self.stage2_cfg['num_channels']
- block_type = self.stage2_cfg['block']
-
- block = self.blocks_dict[block_type]
- num_channels = [channel * block.expansion for channel in num_channels]
- self.transition1 = self._make_transition_layer([stage1_out_channels],
- num_channels)
- self.stage2, pre_stage_channels = self._make_stage(
- self.stage2_cfg, num_channels)
-
- # stage 3
- self.stage3_cfg = self.extra['stage3']
- num_channels = self.stage3_cfg['num_channels']
- block_type = self.stage3_cfg['block']
-
- block = self.blocks_dict[block_type]
- num_channels = [channel * block.expansion for channel in num_channels]
- self.transition2 = self._make_transition_layer(pre_stage_channels,
- num_channels)
- self.stage3, pre_stage_channels = self._make_stage(
- self.stage3_cfg, num_channels)
-
- # stage 4
- self.stage4_cfg = self.extra['stage4']
- num_channels = self.stage4_cfg['num_channels']
- block_type = self.stage4_cfg['block']
-
- block = self.blocks_dict[block_type]
- num_channels = [channel * block.expansion for channel in num_channels]
- self.transition3 = self._make_transition_layer(pre_stage_channels,
- num_channels)
- self.stage4, pre_stage_channels = self._make_stage(
- self.stage4_cfg, num_channels, multiscale_output=multiscale_output)
-
- @property
- def norm1(self):
- """nn.Module: the normalization layer named "norm1" """
- return getattr(self, self.norm1_name)
-
- @property
- def norm2(self):
- """nn.Module: the normalization layer named "norm2" """
- return getattr(self, self.norm2_name)
-
- def _make_transition_layer(self, num_channels_pre_layer,
- num_channels_cur_layer):
- num_branches_cur = len(num_channels_cur_layer)
- num_branches_pre = len(num_channels_pre_layer)
-
- transition_layers = []
- for i in range(num_branches_cur):
- if i < num_branches_pre:
- if num_channels_cur_layer[i] != num_channels_pre_layer[i]:
- transition_layers.append(
- nn.Sequential(
- build_conv_layer(
- self.conv_cfg,
- num_channels_pre_layer[i],
- num_channels_cur_layer[i],
- kernel_size=3,
- stride=1,
- padding=1,
- bias=False),
- build_norm_layer(self.norm_cfg,
- num_channels_cur_layer[i])[1],
- nn.ReLU(inplace=True)))
- else:
- transition_layers.append(None)
- else:
- conv_downsamples = []
- for j in range(i + 1 - num_branches_pre):
- in_channels = num_channels_pre_layer[-1]
- out_channels = num_channels_cur_layer[i] \
- if j == i - num_branches_pre else in_channels
- conv_downsamples.append(
- nn.Sequential(
- build_conv_layer(
- self.conv_cfg,
- in_channels,
- out_channels,
- kernel_size=3,
- stride=2,
- padding=1,
- bias=False),
- build_norm_layer(self.norm_cfg, out_channels)[1],
- nn.ReLU(inplace=True)))
- transition_layers.append(nn.Sequential(*conv_downsamples))
-
- return nn.ModuleList(transition_layers)
-
- def _make_layer(self, block, inplanes, planes, blocks, stride=1):
- downsample = None
- if stride != 1 or inplanes != planes * block.expansion:
- downsample = nn.Sequential(
- build_conv_layer(
- self.conv_cfg,
- inplanes,
- planes * block.expansion,
- kernel_size=1,
- stride=stride,
- bias=False),
- build_norm_layer(self.norm_cfg, planes * block.expansion)[1])
-
- layers = []
- block_init_cfg = None
- if self.pretrained is None and not hasattr(
- self, 'init_cfg') and self.zero_init_residual:
- if block is BasicBlock:
- block_init_cfg = dict(
- type='Constant', val=0, override=dict(name='norm2'))
- elif block is Bottleneck:
- block_init_cfg = dict(
- type='Constant', val=0, override=dict(name='norm3'))
- layers.append(
- block(
- inplanes,
- planes,
- stride,
- downsample=downsample,
- with_cp=self.with_cp,
- norm_cfg=self.norm_cfg,
- conv_cfg=self.conv_cfg,
- init_cfg=block_init_cfg,
- ))
- inplanes = planes * block.expansion
- for i in range(1, blocks):
- layers.append(
- block(
- inplanes,
- planes,
- with_cp=self.with_cp,
- norm_cfg=self.norm_cfg,
- conv_cfg=self.conv_cfg,
- init_cfg=block_init_cfg))
-
- return Sequential(*layers)
-
- def _make_stage(self, layer_config, in_channels, multiscale_output=True):
- num_modules = layer_config['num_modules']
- num_branches = layer_config['num_branches']
- num_blocks = layer_config['num_blocks']
- num_channels = layer_config['num_channels']
- block = self.blocks_dict[layer_config['block']]
-
- hr_modules = []
- block_init_cfg = None
- if self.pretrained is None and not hasattr(
- self, 'init_cfg') and self.zero_init_residual:
- if block is BasicBlock:
- block_init_cfg = dict(
- type='Constant', val=0, override=dict(name='norm2'))
- elif block is Bottleneck:
- block_init_cfg = dict(
- type='Constant', val=0, override=dict(name='norm3'))
-
- for i in range(num_modules):
- # multi_scale_output is only used for the last module
- if not multiscale_output and i == num_modules - 1:
- reset_multiscale_output = False
- else:
- reset_multiscale_output = True
-
- hr_modules.append(
- HRModule(
- num_branches,
- block,
- num_blocks,
- in_channels,
- num_channels,
- reset_multiscale_output,
- with_cp=self.with_cp,
- norm_cfg=self.norm_cfg,
- conv_cfg=self.conv_cfg,
- block_init_cfg=block_init_cfg))
-
- return Sequential(*hr_modules), in_channels
-
- def forward(self, x):
- """Forward function."""
- x = self.conv1(x)
- x = self.norm1(x)
- x = self.relu(x)
- x = self.conv2(x)
- x = self.norm2(x)
- x = self.relu(x)
- x = self.layer1(x)
-
- x_list = []
- for i in range(self.stage2_cfg['num_branches']):
- if self.transition1[i] is not None:
- x_list.append(self.transition1[i](x))
- else:
- x_list.append(x)
- y_list = self.stage2(x_list)
-
- x_list = []
- for i in range(self.stage3_cfg['num_branches']):
- if self.transition2[i] is not None:
- x_list.append(self.transition2[i](y_list[-1]))
- else:
- x_list.append(y_list[i])
- y_list = self.stage3(x_list)
-
- x_list = []
- for i in range(self.stage4_cfg['num_branches']):
- if self.transition3[i] is not None:
- x_list.append(self.transition3[i](y_list[-1]))
- else:
- x_list.append(y_list[i])
- y_list = self.stage4(x_list)
-
- return y_list
-
- def train(self, mode=True):
- """Convert the model into training mode will keeping the normalization
- layer freezed."""
- super(HRNet, self).train(mode)
- if mode and self.norm_eval:
- for m in self.modules():
- # trick: eval have effect on BatchNorm only
- if isinstance(m, _BatchNorm):
- m.eval()
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