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import torch.nn as nn
import torch.nn.functional as F
def conv3x3(in_planes, out_planes, stride=1, groups=1, dilation=1):
"""3x3 convolution with padding"""
return nn.Conv2d(in_planes,
out_planes,
kernel_size=3,
stride=stride,
padding=dilation,
groups=groups,
bias=False,
dilation=dilation)
class BasicBlock(nn.Module):
expansion = 1
def __init__(self,
inplanes,
planes,
stride=1,
downsample=None,
groups=1,
base_width=64,
dilation=1,
norm_layer=None,
dcn=None):
super(BasicBlock, self).__init__()
if norm_layer is None:
norm_layer = nn.BatchNorm2d
if groups != 1 or base_width != 64:
raise ValueError(
'BasicBlock only supports groups=1 and base_width=64')
if dilation > 1:
raise NotImplementedError(
"Dilation > 1 not supported in BasicBlock")
# Both self.conv1 and self.downsample layers downsample the input when stride != 1
self.conv1 = conv3x3(inplanes, planes, stride)
self.bn1 = norm_layer(planes)
self.relu = nn.ReLU(inplace=True)
self.conv2 = conv3x3(planes, planes)
self.bn2 = norm_layer(planes)
self.downsample = downsample
self.stride = stride
def forward(self, x):
identity = x
out = self.conv1(x)
out = self.bn1(out)
out = self.relu(out)
out = self.conv2(out)
out = self.bn2(out)
if self.downsample is not None:
identity = self.downsample(x)
out += identity
out = self.relu(out)
return out
class Bottleneck(nn.Module):
expansion = 4
def __init__(self,
inplanes,
planes,
stride=1,
downsample=None,
norm_layer=nn.BatchNorm2d,
dcn=None):
super(Bottleneck, self).__init__()
self.dcn = dcn
self.with_dcn = dcn is not None
self.conv1 = nn.Conv2d(inplanes, planes, kernel_size=1, bias=False)
self.bn1 = norm_layer(planes, momentum=0.1)
self.conv2 = nn.Conv2d(planes,
planes,
kernel_size=3,
stride=stride,
padding=1,
bias=False)
self.bn2 = norm_layer(planes, momentum=0.1)
self.conv3 = nn.Conv2d(planes, planes * 4, kernel_size=1, bias=False)
self.bn3 = norm_layer(planes * 4, momentum=0.1)
self.downsample = downsample
self.stride = stride
def forward(self, x):
residual = x
out = F.relu(self.bn1(self.conv1(x)), inplace=True)
if not self.with_dcn:
out = F.relu(self.bn2(self.conv2(out)), inplace=True)
elif self.with_modulated_dcn:
offset_mask = self.conv2_offset(out)
offset = offset_mask[:, :18 * self.deformable_groups, :, :]
mask = offset_mask[:, -9 * self.deformable_groups:, :, :]
mask = mask.sigmoid()
out = F.relu(self.bn2(self.conv2(out, offset, mask)))
else:
offset = self.conv2_offset(out)
out = F.relu(self.bn2(self.conv2(out, offset)), inplace=True)
out = self.conv3(out)
out = self.bn3(out)
if self.downsample is not None:
residual = self.downsample(x)
out += residual
out = F.relu(out)
return out
class ResNet(nn.Module):
""" ResNet """
def __init__(self,
architecture,
norm_layer=nn.BatchNorm2d,
dcn=None,
stage_with_dcn=(False, False, False, False)):
super(ResNet, self).__init__()
self._norm_layer = norm_layer
assert architecture in [
"resnet18", "resnet34", "resnet50", "resnet101", 'resnet152'
]
layers = {
'resnet18': [2, 2, 2, 2],
'resnet34': [3, 4, 6, 3],
'resnet50': [3, 4, 6, 3],
'resnet101': [3, 4, 23, 3],
'resnet152': [3, 8, 36, 3],
}
self.inplanes = 64
if architecture == "resnet18" or architecture == 'resnet34':
self.block = BasicBlock
else:
self.block = Bottleneck
self.layers = layers[architecture]
self.conv1 = nn.Conv2d(3,
64,
kernel_size=7,
stride=2,
padding=3,
bias=False)
self.bn1 = norm_layer(64, eps=1e-5, momentum=0.1, affine=True)
self.relu = nn.ReLU(inplace=True)
self.maxpool = nn.MaxPool2d(kernel_size=3, stride=2, padding=1)
stage_dcn = [dcn if with_dcn else None for with_dcn in stage_with_dcn]
self.layer1 = self.make_layer(self.block,
64,
self.layers[0],
dcn=stage_dcn[0])
self.layer2 = self.make_layer(self.block,
128,
self.layers[1],
stride=2,
dcn=stage_dcn[1])
self.layer3 = self.make_layer(self.block,
256,
self.layers[2],
stride=2,
dcn=stage_dcn[2])
self.layer4 = self.make_layer(self.block,
512,
self.layers[3],
stride=2,
dcn=stage_dcn[3])
def forward(self, x):
x = self.maxpool(self.relu(self.bn1(self.conv1(x)))) # 64 * h/4 * w/4
x = self.layer1(x) # 256 * h/4 * w/4
x = self.layer2(x) # 512 * h/8 * w/8
x = self.layer3(x) # 1024 * h/16 * w/16
x = self.layer4(x) # 2048 * h/32 * w/32
return x
def stages(self):
return [self.layer1, self.layer2, self.layer3, self.layer4]
def make_layer(self, block, planes, blocks, stride=1, dcn=None):
downsample = None
if stride != 1 or self.inplanes != planes * block.expansion:
downsample = nn.Sequential(
nn.Conv2d(self.inplanes,
planes * block.expansion,
kernel_size=1,
stride=stride,
bias=False),
self._norm_layer(planes * block.expansion),
)
layers = []
layers.append(
block(self.inplanes,
planes,
stride,
downsample,
norm_layer=self._norm_layer,
dcn=dcn))
self.inplanes = planes * block.expansion
for i in range(1, blocks):
layers.append(
block(self.inplanes,
planes,
norm_layer=self._norm_layer,
dcn=dcn))
return nn.Sequential(*layers)