| |
| import logging |
|
|
| import torch.nn as nn |
|
|
| from .utils import constant_init, kaiming_init, normal_init |
|
|
|
|
| def conv3x3(in_planes, out_planes, dilation=1): |
| """3x3 convolution with padding.""" |
| return nn.Conv2d( |
| in_planes, |
| out_planes, |
| kernel_size=3, |
| padding=dilation, |
| dilation=dilation) |
|
|
|
|
| def make_vgg_layer(inplanes, |
| planes, |
| num_blocks, |
| dilation=1, |
| with_bn=False, |
| ceil_mode=False): |
| layers = [] |
| for _ in range(num_blocks): |
| layers.append(conv3x3(inplanes, planes, dilation)) |
| if with_bn: |
| layers.append(nn.BatchNorm2d(planes)) |
| layers.append(nn.ReLU(inplace=True)) |
| inplanes = planes |
| layers.append(nn.MaxPool2d(kernel_size=2, stride=2, ceil_mode=ceil_mode)) |
|
|
| return layers |
|
|
|
|
| class VGG(nn.Module): |
| """VGG backbone. |
| |
| Args: |
| depth (int): Depth of vgg, from {11, 13, 16, 19}. |
| with_bn (bool): Use BatchNorm or not. |
| num_classes (int): number of classes for classification. |
| num_stages (int): VGG stages, normally 5. |
| dilations (Sequence[int]): Dilation of each stage. |
| out_indices (Sequence[int]): Output from which stages. |
| frozen_stages (int): Stages to be frozen (all param fixed). -1 means |
| not freezing any parameters. |
| bn_eval (bool): Whether to set BN layers as eval mode, namely, freeze |
| running stats (mean and var). |
| bn_frozen (bool): Whether to freeze weight and bias of BN layers. |
| """ |
|
|
| arch_settings = { |
| 11: (1, 1, 2, 2, 2), |
| 13: (2, 2, 2, 2, 2), |
| 16: (2, 2, 3, 3, 3), |
| 19: (2, 2, 4, 4, 4) |
| } |
|
|
| def __init__(self, |
| depth, |
| with_bn=False, |
| num_classes=-1, |
| num_stages=5, |
| dilations=(1, 1, 1, 1, 1), |
| out_indices=(0, 1, 2, 3, 4), |
| frozen_stages=-1, |
| bn_eval=True, |
| bn_frozen=False, |
| ceil_mode=False, |
| with_last_pool=True): |
| super(VGG, self).__init__() |
| if depth not in self.arch_settings: |
| raise KeyError(f'invalid depth {depth} for vgg') |
| assert num_stages >= 1 and num_stages <= 5 |
| stage_blocks = self.arch_settings[depth] |
| self.stage_blocks = stage_blocks[:num_stages] |
| assert len(dilations) == num_stages |
| assert max(out_indices) <= num_stages |
|
|
| self.num_classes = num_classes |
| self.out_indices = out_indices |
| self.frozen_stages = frozen_stages |
| self.bn_eval = bn_eval |
| self.bn_frozen = bn_frozen |
|
|
| self.inplanes = 3 |
| start_idx = 0 |
| vgg_layers = [] |
| self.range_sub_modules = [] |
| for i, num_blocks in enumerate(self.stage_blocks): |
| num_modules = num_blocks * (2 + with_bn) + 1 |
| end_idx = start_idx + num_modules |
| dilation = dilations[i] |
| planes = 64 * 2**i if i < 4 else 512 |
| vgg_layer = make_vgg_layer( |
| self.inplanes, |
| planes, |
| num_blocks, |
| dilation=dilation, |
| with_bn=with_bn, |
| ceil_mode=ceil_mode) |
| vgg_layers.extend(vgg_layer) |
| self.inplanes = planes |
| self.range_sub_modules.append([start_idx, end_idx]) |
| start_idx = end_idx |
| if not with_last_pool: |
| vgg_layers.pop(-1) |
| self.range_sub_modules[-1][1] -= 1 |
| self.module_name = 'features' |
| self.add_module(self.module_name, nn.Sequential(*vgg_layers)) |
|
|
| if self.num_classes > 0: |
| self.classifier = nn.Sequential( |
| nn.Linear(512 * 7 * 7, 4096), |
| nn.ReLU(True), |
| nn.Dropout(), |
| nn.Linear(4096, 4096), |
| nn.ReLU(True), |
| nn.Dropout(), |
| nn.Linear(4096, num_classes), |
| ) |
|
|
| def init_weights(self, pretrained=None): |
| if isinstance(pretrained, str): |
| logger = logging.getLogger() |
| from ..runner import load_checkpoint |
| load_checkpoint(self, pretrained, strict=False, logger=logger) |
| elif pretrained is None: |
| for m in self.modules(): |
| if isinstance(m, nn.Conv2d): |
| kaiming_init(m) |
| elif isinstance(m, nn.BatchNorm2d): |
| constant_init(m, 1) |
| elif isinstance(m, nn.Linear): |
| normal_init(m, std=0.01) |
| else: |
| raise TypeError('pretrained must be a str or None') |
|
|
| def forward(self, x): |
| outs = [] |
| vgg_layers = getattr(self, self.module_name) |
| for i in range(len(self.stage_blocks)): |
| for j in range(*self.range_sub_modules[i]): |
| vgg_layer = vgg_layers[j] |
| x = vgg_layer(x) |
| if i in self.out_indices: |
| outs.append(x) |
| if self.num_classes > 0: |
| x = x.view(x.size(0), -1) |
| x = self.classifier(x) |
| outs.append(x) |
| if len(outs) == 1: |
| return outs[0] |
| else: |
| return tuple(outs) |
|
|
| def train(self, mode=True): |
| super(VGG, self).train(mode) |
| if self.bn_eval: |
| for m in self.modules(): |
| if isinstance(m, nn.BatchNorm2d): |
| m.eval() |
| if self.bn_frozen: |
| for params in m.parameters(): |
| params.requires_grad = False |
| vgg_layers = getattr(self, self.module_name) |
| if mode and self.frozen_stages >= 0: |
| for i in range(self.frozen_stages): |
| for j in range(*self.range_sub_modules[i]): |
| mod = vgg_layers[j] |
| mod.eval() |
| for param in mod.parameters(): |
| param.requires_grad = False |
|
|