""" ResNeSt Models
Paper: `ResNeSt: Split-Attention Networks` - https://arxiv.org/abs/2004.08955
Adapted from original PyTorch impl w/ weights at https://github.com/zhanghang1989/ResNeSt by Hang Zhang
Modified for torchscript compat, and consistency with timm by Ross Wightman
"""
from torch import nn
from timm.data import IMAGENET_DEFAULT_MEAN, IMAGENET_DEFAULT_STD
from timm.layers import SplitAttn
from ._builder import build_model_with_cfg
from ._registry import register_model
from .resnet import ResNet
def _cfg(url='', **kwargs):
return {
'url': url,
'num_classes': 1000, 'input_size': (3, 224, 224), 'pool_size': (7, 7),
'crop_pct': 0.875, 'interpolation': 'bilinear',
'mean': IMAGENET_DEFAULT_MEAN, 'std': IMAGENET_DEFAULT_STD,
'first_conv': 'conv1.0', 'classifier': 'fc',
**kwargs
}
default_cfgs = {
'resnest14d': _cfg(
url='https://github.com/rwightman/pytorch-image-models/releases/download/v0.1-weights/gluon_resnest14-9c8fe254.pth'),
'resnest26d': _cfg(
url='https://github.com/rwightman/pytorch-image-models/releases/download/v0.1-weights/gluon_resnest26-50eb607c.pth'),
'resnest50d': _cfg(
url='https://github.com/rwightman/pytorch-image-models/releases/download/v0.1-resnest/resnest50-528c19ca.pth'),
'resnest101e': _cfg(
url='https://github.com/rwightman/pytorch-image-models/releases/download/v0.1-resnest/resnest101-22405ba7.pth',
input_size=(3, 256, 256), pool_size=(8, 8)),
'resnest200e': _cfg(
url='https://github.com/rwightman/pytorch-image-models/releases/download/v0.1-resnest/resnest200-75117900.pth',
input_size=(3, 320, 320), pool_size=(10, 10), crop_pct=0.909, interpolation='bicubic'),
'resnest269e': _cfg(
url='https://github.com/rwightman/pytorch-image-models/releases/download/v0.1-resnest/resnest269-0cc87c48.pth',
input_size=(3, 416, 416), pool_size=(13, 13), crop_pct=0.928, interpolation='bicubic'),
'resnest50d_4s2x40d': _cfg(
url='https://github.com/rwightman/pytorch-image-models/releases/download/v0.1-resnest/resnest50_fast_4s2x40d-41d14ed0.pth',
interpolation='bicubic'),
'resnest50d_1s4x24d': _cfg(
url='https://github.com/rwightman/pytorch-image-models/releases/download/v0.1-resnest/resnest50_fast_1s4x24d-d4a4f76f.pth',
interpolation='bicubic')
}
class ResNestBottleneck(nn.Module):
"""ResNet Bottleneck
"""
# pylint: disable=unused-argument
expansion = 4
def __init__(
self,
inplanes,
planes,
stride=1,
downsample=None,
radix=1,
cardinality=1,
base_width=64,
avd=False,
avd_first=False,
is_first=False,
reduce_first=1,
dilation=1,
first_dilation=None,
act_layer=nn.ReLU,
norm_layer=nn.BatchNorm2d,
attn_layer=None,
aa_layer=None,
drop_block=None,
drop_path=None,
):
super(ResNestBottleneck, self).__init__()
assert reduce_first == 1 # not supported
assert attn_layer is None # not supported
assert aa_layer is None # TODO not yet supported
assert drop_path is None # TODO not yet supported
group_width = int(planes * (base_width / 64.)) * cardinality
first_dilation = first_dilation or dilation
if avd and (stride > 1 or is_first):
avd_stride = stride
stride = 1
else:
avd_stride = 0
self.radix = radix
self.conv1 = nn.Conv2d(inplanes, group_width, kernel_size=1, bias=False)
self.bn1 = norm_layer(group_width)
self.act1 = act_layer(inplace=True)
self.avd_first = nn.AvgPool2d(3, avd_stride, padding=1) if avd_stride > 0 and avd_first else None
if self.radix >= 1:
self.conv2 = SplitAttn(
group_width, group_width, kernel_size=3, stride=stride, padding=first_dilation,
dilation=first_dilation, groups=cardinality, radix=radix, norm_layer=norm_layer, drop_layer=drop_block)
self.bn2 = nn.Identity()
self.drop_block = nn.Identity()
self.act2 = nn.Identity()
else:
self.conv2 = nn.Conv2d(
group_width, group_width, kernel_size=3, stride=stride, padding=first_dilation,
dilation=first_dilation, groups=cardinality, bias=False)
self.bn2 = norm_layer(group_width)
self.drop_block = drop_block() if drop_block is not None else nn.Identity()
self.act2 = act_layer(inplace=True)
self.avd_last = nn.AvgPool2d(3, avd_stride, padding=1) if avd_stride > 0 and not avd_first else None
self.conv3 = nn.Conv2d(group_width, planes * 4, kernel_size=1, bias=False)
self.bn3 = norm_layer(planes*4)
self.act3 = act_layer(inplace=True)
self.downsample = downsample
def zero_init_last(self):
if getattr(self.bn3, 'weight', None) is not None:
nn.init.zeros_(self.bn3.weight)
def forward(self, x):
shortcut = x
out = self.conv1(x)
out = self.bn1(out)
out = self.act1(out)
if self.avd_first is not None:
out = self.avd_first(out)
out = self.conv2(out)
out = self.bn2(out)
out = self.drop_block(out)
out = self.act2(out)
if self.avd_last is not None:
out = self.avd_last(out)
out = self.conv3(out)
out = self.bn3(out)
if self.downsample is not None:
shortcut = self.downsample(x)
out += shortcut
out = self.act3(out)
return out
def _create_resnest(variant, pretrained=False, **kwargs):
return build_model_with_cfg(ResNet, variant, pretrained, **kwargs)
@register_model
def resnest14d(pretrained=False, **kwargs):
""" ResNeSt-14d model. Weights ported from GluonCV.
"""
model_kwargs = dict(
block=ResNestBottleneck, layers=[1, 1, 1, 1],
stem_type='deep', stem_width=32, avg_down=True, base_width=64, cardinality=1,
block_args=dict(radix=2, avd=True, avd_first=False), **kwargs)
return _create_resnest('resnest14d', pretrained=pretrained, **model_kwargs)
@register_model
def resnest26d(pretrained=False, **kwargs):
""" ResNeSt-26d model. Weights ported from GluonCV.
"""
model_kwargs = dict(
block=ResNestBottleneck, layers=[2, 2, 2, 2],
stem_type='deep', stem_width=32, avg_down=True, base_width=64, cardinality=1,
block_args=dict(radix=2, avd=True, avd_first=False), **kwargs)
return _create_resnest('resnest26d', pretrained=pretrained, **model_kwargs)
@register_model
def resnest50d(pretrained=False, **kwargs):
""" ResNeSt-50d model. Matches paper ResNeSt-50 model, https://arxiv.org/abs/2004.08955
Since this codebase supports all possible variations, 'd' for deep stem, stem_width 32, avg in downsample.
"""
model_kwargs = dict(
block=ResNestBottleneck, layers=[3, 4, 6, 3],
stem_type='deep', stem_width=32, avg_down=True, base_width=64, cardinality=1,
block_args=dict(radix=2, avd=True, avd_first=False), **kwargs)
return _create_resnest('resnest50d', pretrained=pretrained, **model_kwargs)
@register_model
def resnest101e(pretrained=False, **kwargs):
""" ResNeSt-101e model. Matches paper ResNeSt-101 model, https://arxiv.org/abs/2004.08955
Since this codebase supports all possible variations, 'e' for deep stem, stem_width 64, avg in downsample.
"""
model_kwargs = dict(
block=ResNestBottleneck, layers=[3, 4, 23, 3],
stem_type='deep', stem_width=64, avg_down=True, base_width=64, cardinality=1,
block_args=dict(radix=2, avd=True, avd_first=False), **kwargs)
return _create_resnest('resnest101e', pretrained=pretrained, **model_kwargs)
@register_model
def resnest200e(pretrained=False, **kwargs):
""" ResNeSt-200e model. Matches paper ResNeSt-200 model, https://arxiv.org/abs/2004.08955
Since this codebase supports all possible variations, 'e' for deep stem, stem_width 64, avg in downsample.
"""
model_kwargs = dict(
block=ResNestBottleneck, layers=[3, 24, 36, 3],
stem_type='deep', stem_width=64, avg_down=True, base_width=64, cardinality=1,
block_args=dict(radix=2, avd=True, avd_first=False), **kwargs)
return _create_resnest('resnest200e', pretrained=pretrained, **model_kwargs)
@register_model
def resnest269e(pretrained=False, **kwargs):
""" ResNeSt-269e model. Matches paper ResNeSt-269 model, https://arxiv.org/abs/2004.08955
Since this codebase supports all possible variations, 'e' for deep stem, stem_width 64, avg in downsample.
"""
model_kwargs = dict(
block=ResNestBottleneck, layers=[3, 30, 48, 8],
stem_type='deep', stem_width=64, avg_down=True, base_width=64, cardinality=1,
block_args=dict(radix=2, avd=True, avd_first=False), **kwargs)
return _create_resnest('resnest269e', pretrained=pretrained, **model_kwargs)
@register_model
def resnest50d_4s2x40d(pretrained=False, **kwargs):
"""ResNeSt-50 4s2x40d from https://github.com/zhanghang1989/ResNeSt/blob/master/ablation.md
"""
model_kwargs = dict(
block=ResNestBottleneck, layers=[3, 4, 6, 3],
stem_type='deep', stem_width=32, avg_down=True, base_width=40, cardinality=2,
block_args=dict(radix=4, avd=True, avd_first=True), **kwargs)
return _create_resnest('resnest50d_4s2x40d', pretrained=pretrained, **model_kwargs)
@register_model
def resnest50d_1s4x24d(pretrained=False, **kwargs):
"""ResNeSt-50 1s4x24d from https://github.com/zhanghang1989/ResNeSt/blob/master/ablation.md
"""
model_kwargs = dict(
block=ResNestBottleneck, layers=[3, 4, 6, 3],
stem_type='deep', stem_width=32, avg_down=True, base_width=24, cardinality=4,
block_args=dict(radix=1, avd=True, avd_first=True), **kwargs)
return _create_resnest('resnest50d_1s4x24d', pretrained=pretrained, **model_kwargs)