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"""
https://github.com/PaddlePaddle/PaddleDetection/blob/release/2.6/ppdet/modeling/backbones/cspresnet.py
Copyright(c) 2023 lyuwenyu. All Rights Reserved.
"""
import torch
import torch.nn as nn
import torch.nn.functional as F
from collections import OrderedDict
from .common import get_activation
from ..core import register
__all__ = ['CSPResNet']
donwload_url = {
's': 'https://github.com/lyuwenyu/storage/releases/download/v0.1/CSPResNetb_s_pretrained_from_paddle.pth',
'm': 'https://github.com/lyuwenyu/storage/releases/download/v0.1/CSPResNetb_m_pretrained_from_paddle.pth',
'l': 'https://github.com/lyuwenyu/storage/releases/download/v0.1/CSPResNetb_l_pretrained_from_paddle.pth',
'x': 'https://github.com/lyuwenyu/storage/releases/download/v0.1/CSPResNetb_x_pretrained_from_paddle.pth',
}
class ConvBNLayer(nn.Module):
def __init__(self, ch_in, ch_out, filter_size=3, stride=1, groups=1, padding=0, act=None):
super().__init__()
self.conv = nn.Conv2d(ch_in, ch_out, filter_size, stride, padding, groups=groups, bias=False)
self.bn = nn.BatchNorm2d(ch_out)
self.act = get_activation(act)
def forward(self, x: torch.Tensor) -> torch.Tensor:
x = self.conv(x)
x = self.bn(x)
x = self.act(x)
return x
class RepVggBlock(nn.Module):
def __init__(self, ch_in, ch_out, act='relu', alpha: bool=False):
super().__init__()
self.ch_in = ch_in
self.ch_out = ch_out
self.conv1 = ConvBNLayer(
ch_in, ch_out, 3, stride=1, padding=1, act=None)
self.conv2 = ConvBNLayer(
ch_in, ch_out, 1, stride=1, padding=0, act=None)
self.act = get_activation(act)
if alpha:
self.alpha = nn.Parameter(torch.ones(1, ))
else:
self.alpha = None
def forward(self, x):
if hasattr(self, 'conv'):
y = self.conv(x)
else:
if self.alpha:
y = self.conv1(x) + self.alpha * self.conv2(x)
else:
y = self.conv1(x) + self.conv2(x)
y = self.act(y)
return y
def convert_to_deploy(self):
if not hasattr(self, 'conv'):
self.conv = nn.Conv2d(self.ch_in, self.ch_out, 3, 1, padding=1)
kernel, bias = self.get_equivalent_kernel_bias()
self.conv.weight.data = kernel
self.conv.bias.data = bias
def get_equivalent_kernel_bias(self):
kernel3x3, bias3x3 = self._fuse_bn_tensor(self.conv1)
kernel1x1, bias1x1 = self._fuse_bn_tensor(self.conv2)
if self.alpha:
return kernel3x3 + self.alpha * self._pad_1x1_to_3x3_tensor(
kernel1x1), bias3x3 + self.alpha * bias1x1
else:
return kernel3x3 + self._pad_1x1_to_3x3_tensor(
kernel1x1), bias3x3 + bias1x1
def _pad_1x1_to_3x3_tensor(self, kernel1x1):
if kernel1x1 is None:
return 0
else:
return F.pad(kernel1x1, [1, 1, 1, 1])
def _fuse_bn_tensor(self, branch: ConvBNLayer):
if branch is None:
return 0, 0
kernel = branch.conv.weight
running_mean = branch.norm.running_mean
running_var = branch.norm.running_var
gamma = branch.norm.weight
beta = branch.norm.bias
eps = branch.norm.eps
std = (running_var + eps).sqrt()
t = (gamma / std).reshape(-1, 1, 1, 1)
return kernel * t, beta - running_mean * gamma / std
class BasicBlock(nn.Module):
def __init__(self,
ch_in,
ch_out,
act='relu',
shortcut=True,
use_alpha=False):
super().__init__()
assert ch_in == ch_out
self.conv1 = ConvBNLayer(ch_in, ch_out, 3, stride=1, padding=1, act=act)
self.conv2 = RepVggBlock(ch_out, ch_out, act=act, alpha=use_alpha)
self.shortcut = shortcut
def forward(self, x):
y = self.conv1(x)
y = self.conv2(y)
if self.shortcut:
return x + y
else:
return y
class EffectiveSELayer(nn.Module):
""" Effective Squeeze-Excitation
From `CenterMask : Real-Time Anchor-Free Instance Segmentation` - https://arxiv.org/abs/1911.06667
"""
def __init__(self, channels, act='hardsigmoid'):
super(EffectiveSELayer, self).__init__()
self.fc = nn.Conv2d(channels, channels, kernel_size=1, padding=0)
self.act = get_activation(act)
def forward(self, x: torch.Tensor):
x_se = x.mean((2, 3), keepdim=True)
x_se = self.fc(x_se)
x_se = self.act(x_se)
return x * x_se
class CSPResStage(nn.Module):
def __init__(self,
block_fn,
ch_in,
ch_out,
n,
stride,
act='relu',
attn='eca',
use_alpha=False):
super().__init__()
ch_mid = (ch_in + ch_out) // 2
if stride == 2:
self.conv_down = ConvBNLayer(
ch_in, ch_mid, 3, stride=2, padding=1, act=act)
else:
self.conv_down = None
self.conv1 = ConvBNLayer(ch_mid, ch_mid // 2, 1, act=act)
self.conv2 = ConvBNLayer(ch_mid, ch_mid // 2, 1, act=act)
self.blocks = nn.Sequential(*[
block_fn(
ch_mid // 2,
ch_mid // 2,
act=act,
shortcut=True,
use_alpha=use_alpha) for i in range(n)
])
if attn:
self.attn = EffectiveSELayer(ch_mid, act='hardsigmoid')
else:
self.attn = None
self.conv3 = ConvBNLayer(ch_mid, ch_out, 1, act=act)
def forward(self, x):
if self.conv_down is not None:
x = self.conv_down(x)
y1 = self.conv1(x)
y2 = self.blocks(self.conv2(x))
y = torch.concat([y1, y2], dim=1)
if self.attn is not None:
y = self.attn(y)
y = self.conv3(y)
return y
@register()
class CSPResNet(nn.Module):
layers = [3, 6, 6, 3]
channels = [64, 128, 256, 512, 1024]
model_cfg = {
's': {'depth_mult': 0.33, 'width_mult': 0.50, },
'm': {'depth_mult': 0.67, 'width_mult': 0.75, },
'l': {'depth_mult': 1.00, 'width_mult': 1.00, },
'x': {'depth_mult': 1.33, 'width_mult': 1.25, },
}
def __init__(self,
name: str,
act='silu',
return_idx=[1, 2, 3],
use_large_stem=True,
use_alpha=False,
pretrained=False):
super().__init__()
depth_mult = self.model_cfg[name]['depth_mult']
width_mult = self.model_cfg[name]['width_mult']
channels = [max(round(c * width_mult), 1) for c in self.channels]
layers = [max(round(l * depth_mult), 1) for l in self.layers]
act = get_activation(act)
if use_large_stem:
self.stem = nn.Sequential(OrderedDict([
('conv1', ConvBNLayer(
3, channels[0] // 2, 3, stride=2, padding=1, act=act)),
('conv2', ConvBNLayer(
channels[0] // 2,
channels[0] // 2,
3,
stride=1,
padding=1,
act=act)), ('conv3', ConvBNLayer(
channels[0] // 2,
channels[0],
3,
stride=1,
padding=1,
act=act))]))
else:
self.stem = nn.Sequential(OrderedDict([
('conv1', ConvBNLayer(
3, channels[0] // 2, 3, stride=2, padding=1, act=act)),
('conv2', ConvBNLayer(
channels[0] // 2,
channels[0],
3,
stride=1,
padding=1,
act=act))]))
n = len(channels) - 1
self.stages = nn.Sequential(OrderedDict([(str(i), CSPResStage(
BasicBlock,
channels[i],
channels[i + 1],
layers[i],
2,
act=act,
use_alpha=use_alpha)) for i in range(n)]))
self._out_channels = channels[1:]
self._out_strides = [4 * 2**i for i in range(n)]
self.return_idx = return_idx
if pretrained:
if isinstance(pretrained, bool) or 'http' in pretrained:
state = torch.hub.load_state_dict_from_url(donwload_url[name], map_location='cpu')
else:
state = torch.load(pretrained, map_location='cpu')
self.load_state_dict(state)
print(f'Load CSPResNet_{name} state_dict')
def forward(self, x):
x = self.stem(x)
outs = []
for idx, stage in enumerate(self.stages):
x = stage(x)
if idx in self.return_idx:
outs.append(x)
return outs