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王庆刚
2024-05-20 20:01:06 +08:00
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# Ultralytics YOLO 🚀, AGPL-3.0 license
"""
Ultralytics modules. Visualize with:
from ultralytics.nn.modules import *
import torch
import os
x = torch.ones(1, 128, 40, 40)
m = Conv(128, 128)
f = f'{m._get_name()}.onnx'
torch.onnx.export(m, x, f)
os.system(f'onnxsim {f} {f} && open {f}')
"""
from .block import (C1, C2, C3, C3TR, DFL, SPP, SPPF, Bottleneck, BottleneckCSP, C2f, C3Ghost, C3x, GhostBottleneck,
HGBlock, HGStem, Proto, RepC3)
from .conv import (CBAM, ChannelAttention, Concat, Conv, Conv2, ConvTranspose, DWConv, DWConvTranspose2d, Focus,
GhostConv, LightConv, RepConv, SpatialAttention)
from .head import Classify, Detect, Pose, RTDETRDecoder, Segment
from .transformer import (AIFI, MLP, DeformableTransformerDecoder, DeformableTransformerDecoderLayer, LayerNorm2d,
MLPBlock, MSDeformAttn, TransformerBlock, TransformerEncoderLayer, TransformerLayer)
__all__ = ('Conv', 'Conv2', 'LightConv', 'RepConv', 'DWConv', 'DWConvTranspose2d', 'ConvTranspose', 'Focus',
'GhostConv', 'ChannelAttention', 'SpatialAttention', 'CBAM', 'Concat', 'TransformerLayer',
'TransformerBlock', 'MLPBlock', 'LayerNorm2d', 'DFL', 'HGBlock', 'HGStem', 'SPP', 'SPPF', 'C1', 'C2', 'C3',
'C2f', 'C3x', 'C3TR', 'C3Ghost', 'GhostBottleneck', 'Bottleneck', 'BottleneckCSP', 'Proto', 'Detect',
'Segment', 'Pose', 'Classify', 'TransformerEncoderLayer', 'RepC3', 'RTDETRDecoder', 'AIFI',
'DeformableTransformerDecoder', 'DeformableTransformerDecoderLayer', 'MSDeformAttn', 'MLP')

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# Ultralytics YOLO 🚀, AGPL-3.0 license
"""
Block modules
"""
import torch
import torch.nn as nn
import torch.nn.functional as F
from .conv import Conv, DWConv, GhostConv, LightConv, RepConv
from .transformer import TransformerBlock
__all__ = ('DFL', 'HGBlock', 'HGStem', 'SPP', 'SPPF', 'C1', 'C2', 'C3', 'C2f', 'C3x', 'C3TR', 'C3Ghost',
'GhostBottleneck', 'Bottleneck', 'BottleneckCSP', 'Proto', 'RepC3')
class DFL(nn.Module):
"""
Integral module of Distribution Focal Loss (DFL).
Proposed in Generalized Focal Loss https://ieeexplore.ieee.org/document/9792391
"""
def __init__(self, c1=16):
"""Initialize a convolutional layer with a given number of input channels."""
super().__init__()
self.conv = nn.Conv2d(c1, 1, 1, bias=False).requires_grad_(False)
x = torch.arange(c1, dtype=torch.float)
self.conv.weight.data[:] = nn.Parameter(x.view(1, c1, 1, 1))
self.c1 = c1
def forward(self, x):
"""Applies a transformer layer on input tensor 'x' and returns a tensor."""
b, c, a = x.shape # batch, channels, anchors
return self.conv(x.view(b, 4, self.c1, a).transpose(2, 1).softmax(1)).view(b, 4, a)
# return self.conv(x.view(b, self.c1, 4, a).softmax(1)).view(b, 4, a)
class Proto(nn.Module):
"""YOLOv8 mask Proto module for segmentation models."""
def __init__(self, c1, c_=256, c2=32): # ch_in, number of protos, number of masks
super().__init__()
self.cv1 = Conv(c1, c_, k=3)
self.upsample = nn.ConvTranspose2d(c_, c_, 2, 2, 0, bias=True) # nn.Upsample(scale_factor=2, mode='nearest')
self.cv2 = Conv(c_, c_, k=3)
self.cv3 = Conv(c_, c2)
def forward(self, x):
"""Performs a forward pass through layers using an upsampled input image."""
return self.cv3(self.cv2(self.upsample(self.cv1(x))))
class HGStem(nn.Module):
"""StemBlock of PPHGNetV2 with 5 convolutions and one maxpool2d.
https://github.com/PaddlePaddle/PaddleDetection/blob/develop/ppdet/modeling/backbones/hgnet_v2.py
"""
def __init__(self, c1, cm, c2):
super().__init__()
self.stem1 = Conv(c1, cm, 3, 2, act=nn.ReLU())
self.stem2a = Conv(cm, cm // 2, 2, 1, 0, act=nn.ReLU())
self.stem2b = Conv(cm // 2, cm, 2, 1, 0, act=nn.ReLU())
self.stem3 = Conv(cm * 2, cm, 3, 2, act=nn.ReLU())
self.stem4 = Conv(cm, c2, 1, 1, act=nn.ReLU())
self.pool = nn.MaxPool2d(kernel_size=2, stride=1, padding=0, ceil_mode=True)
def forward(self, x):
"""Forward pass of a PPHGNetV2 backbone layer."""
x = self.stem1(x)
x = F.pad(x, [0, 1, 0, 1])
x2 = self.stem2a(x)
x2 = F.pad(x2, [0, 1, 0, 1])
x2 = self.stem2b(x2)
x1 = self.pool(x)
x = torch.cat([x1, x2], dim=1)
x = self.stem3(x)
x = self.stem4(x)
return x
class HGBlock(nn.Module):
"""HG_Block of PPHGNetV2 with 2 convolutions and LightConv.
https://github.com/PaddlePaddle/PaddleDetection/blob/develop/ppdet/modeling/backbones/hgnet_v2.py
"""
def __init__(self, c1, cm, c2, k=3, n=6, lightconv=False, shortcut=False, act=nn.ReLU()):
super().__init__()
block = LightConv if lightconv else Conv
self.m = nn.ModuleList(block(c1 if i == 0 else cm, cm, k=k, act=act) for i in range(n))
self.sc = Conv(c1 + n * cm, c2 // 2, 1, 1, act=act) # squeeze conv
self.ec = Conv(c2 // 2, c2, 1, 1, act=act) # excitation conv
self.add = shortcut and c1 == c2
def forward(self, x):
"""Forward pass of a PPHGNetV2 backbone layer."""
y = [x]
y.extend(m(y[-1]) for m in self.m)
y = self.ec(self.sc(torch.cat(y, 1)))
return y + x if self.add else y
class SPP(nn.Module):
"""Spatial Pyramid Pooling (SPP) layer https://arxiv.org/abs/1406.4729."""
def __init__(self, c1, c2, k=(5, 9, 13)):
"""Initialize the SPP layer with input/output channels and pooling kernel sizes."""
super().__init__()
c_ = c1 // 2 # hidden channels
self.cv1 = Conv(c1, c_, 1, 1)
self.cv2 = Conv(c_ * (len(k) + 1), c2, 1, 1)
self.m = nn.ModuleList([nn.MaxPool2d(kernel_size=x, stride=1, padding=x // 2) for x in k])
def forward(self, x):
"""Forward pass of the SPP layer, performing spatial pyramid pooling."""
x = self.cv1(x)
return self.cv2(torch.cat([x] + [m(x) for m in self.m], 1))
class SPPF(nn.Module):
"""Spatial Pyramid Pooling - Fast (SPPF) layer for YOLOv5 by Glenn Jocher."""
def __init__(self, c1, c2, k=5): # equivalent to SPP(k=(5, 9, 13))
super().__init__()
c_ = c1 // 2 # hidden channels
self.cv1 = Conv(c1, c_, 1, 1)
self.cv2 = Conv(c_ * 4, c2, 1, 1)
self.m = nn.MaxPool2d(kernel_size=k, stride=1, padding=k // 2)
def forward(self, x):
"""Forward pass through Ghost Convolution block."""
x = self.cv1(x)
y1 = self.m(x)
y2 = self.m(y1)
return self.cv2(torch.cat((x, y1, y2, self.m(y2)), 1))
class C1(nn.Module):
"""CSP Bottleneck with 1 convolution."""
def __init__(self, c1, c2, n=1): # ch_in, ch_out, number
super().__init__()
self.cv1 = Conv(c1, c2, 1, 1)
self.m = nn.Sequential(*(Conv(c2, c2, 3) for _ in range(n)))
def forward(self, x):
"""Applies cross-convolutions to input in the C3 module."""
y = self.cv1(x)
return self.m(y) + y
class C2(nn.Module):
"""CSP Bottleneck with 2 convolutions."""
def __init__(self, c1, c2, n=1, shortcut=True, g=1, e=0.5): # ch_in, ch_out, number, shortcut, groups, expansion
super().__init__()
self.c = int(c2 * e) # hidden channels
self.cv1 = Conv(c1, 2 * self.c, 1, 1)
self.cv2 = Conv(2 * self.c, c2, 1) # optional act=FReLU(c2)
# self.attention = ChannelAttention(2 * self.c) # or SpatialAttention()
self.m = nn.Sequential(*(Bottleneck(self.c, self.c, shortcut, g, k=((3, 3), (3, 3)), e=1.0) for _ in range(n)))
def forward(self, x):
"""Forward pass through the CSP bottleneck with 2 convolutions."""
a, b = self.cv1(x).chunk(2, 1)
return self.cv2(torch.cat((self.m(a), b), 1))
class C2f(nn.Module):
"""Faster Implementation of CSP Bottleneck with 2 convolutions."""
def __init__(self, c1, c2, n=1, shortcut=False, g=1, e=0.5): # ch_in, ch_out, number, shortcut, groups, expansion
super().__init__()
self.c = int(c2 * e) # hidden channels
self.cv1 = Conv(c1, 2 * self.c, 1, 1)
self.cv2 = Conv((2 + n) * self.c, c2, 1) # optional act=FReLU(c2)
self.m = nn.ModuleList(Bottleneck(self.c, self.c, shortcut, g, k=((3, 3), (3, 3)), e=1.0) for _ in range(n))
def forward(self, x):
"""Forward pass through C2f layer."""
y = list(self.cv1(x).chunk(2, 1))
y.extend(m(y[-1]) for m in self.m)
return self.cv2(torch.cat(y, 1))
def forward_split(self, x):
"""Forward pass using split() instead of chunk()."""
y = list(self.cv1(x).split((self.c, self.c), 1))
y.extend(m(y[-1]) for m in self.m)
return self.cv2(torch.cat(y, 1))
class C3(nn.Module):
"""CSP Bottleneck with 3 convolutions."""
def __init__(self, c1, c2, n=1, shortcut=True, g=1, e=0.5): # ch_in, ch_out, number, shortcut, groups, expansion
super().__init__()
c_ = int(c2 * e) # hidden channels
self.cv1 = Conv(c1, c_, 1, 1)
self.cv2 = Conv(c1, c_, 1, 1)
self.cv3 = Conv(2 * c_, c2, 1) # optional act=FReLU(c2)
self.m = nn.Sequential(*(Bottleneck(c_, c_, shortcut, g, k=((1, 1), (3, 3)), e=1.0) for _ in range(n)))
def forward(self, x):
"""Forward pass through the CSP bottleneck with 2 convolutions."""
return self.cv3(torch.cat((self.m(self.cv1(x)), self.cv2(x)), 1))
class C3x(C3):
"""C3 module with cross-convolutions."""
def __init__(self, c1, c2, n=1, shortcut=True, g=1, e=0.5):
"""Initialize C3TR instance and set default parameters."""
super().__init__(c1, c2, n, shortcut, g, e)
self.c_ = int(c2 * e)
self.m = nn.Sequential(*(Bottleneck(self.c_, self.c_, shortcut, g, k=((1, 3), (3, 1)), e=1) for _ in range(n)))
class RepC3(nn.Module):
"""Rep C3."""
def __init__(self, c1, c2, n=3, e=1.0):
super().__init__()
c_ = int(c2 * e) # hidden channels
self.cv1 = Conv(c1, c2, 1, 1)
self.cv2 = Conv(c1, c2, 1, 1)
self.m = nn.Sequential(*[RepConv(c_, c_) for _ in range(n)])
self.cv3 = Conv(c_, c2, 1, 1) if c_ != c2 else nn.Identity()
def forward(self, x):
"""Forward pass of RT-DETR neck layer."""
return self.cv3(self.m(self.cv1(x)) + self.cv2(x))
class C3TR(C3):
"""C3 module with TransformerBlock()."""
def __init__(self, c1, c2, n=1, shortcut=True, g=1, e=0.5):
"""Initialize C3Ghost module with GhostBottleneck()."""
super().__init__(c1, c2, n, shortcut, g, e)
c_ = int(c2 * e)
self.m = TransformerBlock(c_, c_, 4, n)
class C3Ghost(C3):
"""C3 module with GhostBottleneck()."""
def __init__(self, c1, c2, n=1, shortcut=True, g=1, e=0.5):
"""Initialize 'SPP' module with various pooling sizes for spatial pyramid pooling."""
super().__init__(c1, c2, n, shortcut, g, e)
c_ = int(c2 * e) # hidden channels
self.m = nn.Sequential(*(GhostBottleneck(c_, c_) for _ in range(n)))
class GhostBottleneck(nn.Module):
"""Ghost Bottleneck https://github.com/huawei-noah/ghostnet."""
def __init__(self, c1, c2, k=3, s=1): # ch_in, ch_out, kernel, stride
super().__init__()
c_ = c2 // 2
self.conv = nn.Sequential(
GhostConv(c1, c_, 1, 1), # pw
DWConv(c_, c_, k, s, act=False) if s == 2 else nn.Identity(), # dw
GhostConv(c_, c2, 1, 1, act=False)) # pw-linear
self.shortcut = nn.Sequential(DWConv(c1, c1, k, s, act=False), Conv(c1, c2, 1, 1,
act=False)) if s == 2 else nn.Identity()
def forward(self, x):
"""Applies skip connection and concatenation to input tensor."""
return self.conv(x) + self.shortcut(x)
class Bottleneck(nn.Module):
"""Standard bottleneck."""
def __init__(self, c1, c2, shortcut=True, g=1, k=(3, 3), e=0.5): # ch_in, ch_out, shortcut, groups, kernels, expand
super().__init__()
c_ = int(c2 * e) # hidden channels
self.cv1 = Conv(c1, c_, k[0], 1)
self.cv2 = Conv(c_, c2, k[1], 1, g=g)
self.add = shortcut and c1 == c2
def forward(self, x):
"""'forward()' applies the YOLOv5 FPN to input data."""
return x + self.cv2(self.cv1(x)) if self.add else self.cv2(self.cv1(x))
class BottleneckCSP(nn.Module):
"""CSP Bottleneck https://github.com/WongKinYiu/CrossStagePartialNetworks."""
def __init__(self, c1, c2, n=1, shortcut=True, g=1, e=0.5): # ch_in, ch_out, number, shortcut, groups, expansion
super().__init__()
c_ = int(c2 * e) # hidden channels
self.cv1 = Conv(c1, c_, 1, 1)
self.cv2 = nn.Conv2d(c1, c_, 1, 1, bias=False)
self.cv3 = nn.Conv2d(c_, c_, 1, 1, bias=False)
self.cv4 = Conv(2 * c_, c2, 1, 1)
self.bn = nn.BatchNorm2d(2 * c_) # applied to cat(cv2, cv3)
self.act = nn.SiLU()
self.m = nn.Sequential(*(Bottleneck(c_, c_, shortcut, g, e=1.0) for _ in range(n)))
def forward(self, x):
"""Applies a CSP bottleneck with 3 convolutions."""
y1 = self.cv3(self.m(self.cv1(x)))
y2 = self.cv2(x)
return self.cv4(self.act(self.bn(torch.cat((y1, y2), 1))))

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# Ultralytics YOLO 🚀, AGPL-3.0 license
"""
Convolution modules
"""
import math
import numpy as np
import torch
import torch.nn as nn
__all__ = ('Conv', 'Conv2', 'LightConv', 'DWConv', 'DWConvTranspose2d', 'ConvTranspose', 'Focus', 'GhostConv',
'ChannelAttention', 'SpatialAttention', 'CBAM', 'Concat', 'RepConv')
def autopad(k, p=None, d=1): # kernel, padding, dilation
"""Pad to 'same' shape outputs."""
if d > 1:
k = d * (k - 1) + 1 if isinstance(k, int) else [d * (x - 1) + 1 for x in k] # actual kernel-size
if p is None:
p = k // 2 if isinstance(k, int) else [x // 2 for x in k] # auto-pad
return p
class Conv(nn.Module):
"""Standard convolution with args(ch_in, ch_out, kernel, stride, padding, groups, dilation, activation)."""
default_act = nn.SiLU() # default activation
def __init__(self, c1, c2, k=1, s=1, p=None, g=1, d=1, act=True):
"""Initialize Conv layer with given arguments including activation."""
super().__init__()
self.conv = nn.Conv2d(c1, c2, k, s, autopad(k, p, d), groups=g, dilation=d, bias=False)
self.bn = nn.BatchNorm2d(c2)
self.act = self.default_act if act is True else act if isinstance(act, nn.Module) else nn.Identity()
def forward(self, x):
"""Apply convolution, batch normalization and activation to input tensor."""
return self.act(self.bn(self.conv(x)))
def forward_fuse(self, x):
"""Perform transposed convolution of 2D data."""
return self.act(self.conv(x))
class Conv2(Conv):
"""Simplified RepConv module with Conv fusing."""
def __init__(self, c1, c2, k=3, s=1, p=None, g=1, d=1, act=True):
"""Initialize Conv layer with given arguments including activation."""
super().__init__(c1, c2, k, s, p, g=g, d=d, act=act)
self.cv2 = nn.Conv2d(c1, c2, 1, s, autopad(1, p, d), groups=g, dilation=d, bias=False) # add 1x1 conv
def forward(self, x):
"""Apply convolution, batch normalization and activation to input tensor."""
return self.act(self.bn(self.conv(x) + self.cv2(x)))
def forward_fuse(self, x):
"""Apply fused convolution, batch normalization and activation to input tensor."""
return self.act(self.bn(self.conv(x)))
def fuse_convs(self):
"""Fuse parallel convolutions."""
w = torch.zeros_like(self.conv.weight.data)
i = [x // 2 for x in w.shape[2:]]
w[:, :, i[0]:i[0] + 1, i[1]:i[1] + 1] = self.cv2.weight.data.clone()
self.conv.weight.data += w
self.__delattr__('cv2')
self.forward = self.forward_fuse
class LightConv(nn.Module):
"""Light convolution with args(ch_in, ch_out, kernel).
https://github.com/PaddlePaddle/PaddleDetection/blob/develop/ppdet/modeling/backbones/hgnet_v2.py
"""
def __init__(self, c1, c2, k=1, act=nn.ReLU()):
"""Initialize Conv layer with given arguments including activation."""
super().__init__()
self.conv1 = Conv(c1, c2, 1, act=False)
self.conv2 = DWConv(c2, c2, k, act=act)
def forward(self, x):
"""Apply 2 convolutions to input tensor."""
return self.conv2(self.conv1(x))
class DWConv(Conv):
"""Depth-wise convolution."""
def __init__(self, c1, c2, k=1, s=1, d=1, act=True): # ch_in, ch_out, kernel, stride, dilation, activation
super().__init__(c1, c2, k, s, g=math.gcd(c1, c2), d=d, act=act)
class DWConvTranspose2d(nn.ConvTranspose2d):
"""Depth-wise transpose convolution."""
def __init__(self, c1, c2, k=1, s=1, p1=0, p2=0): # ch_in, ch_out, kernel, stride, padding, padding_out
super().__init__(c1, c2, k, s, p1, p2, groups=math.gcd(c1, c2))
class ConvTranspose(nn.Module):
"""Convolution transpose 2d layer."""
default_act = nn.SiLU() # default activation
def __init__(self, c1, c2, k=2, s=2, p=0, bn=True, act=True):
"""Initialize ConvTranspose2d layer with batch normalization and activation function."""
super().__init__()
self.conv_transpose = nn.ConvTranspose2d(c1, c2, k, s, p, bias=not bn)
self.bn = nn.BatchNorm2d(c2) if bn else nn.Identity()
self.act = self.default_act if act is True else act if isinstance(act, nn.Module) else nn.Identity()
def forward(self, x):
"""Applies transposed convolutions, batch normalization and activation to input."""
return self.act(self.bn(self.conv_transpose(x)))
def forward_fuse(self, x):
"""Applies activation and convolution transpose operation to input."""
return self.act(self.conv_transpose(x))
class Focus(nn.Module):
"""Focus wh information into c-space."""
def __init__(self, c1, c2, k=1, s=1, p=None, g=1, act=True): # ch_in, ch_out, kernel, stride, padding, groups
super().__init__()
self.conv = Conv(c1 * 4, c2, k, s, p, g, act=act)
# self.contract = Contract(gain=2)
def forward(self, x): # x(b,c,w,h) -> y(b,4c,w/2,h/2)
return self.conv(torch.cat((x[..., ::2, ::2], x[..., 1::2, ::2], x[..., ::2, 1::2], x[..., 1::2, 1::2]), 1))
# return self.conv(self.contract(x))
class GhostConv(nn.Module):
"""Ghost Convolution https://github.com/huawei-noah/ghostnet."""
def __init__(self, c1, c2, k=1, s=1, g=1, act=True): # ch_in, ch_out, kernel, stride, groups
super().__init__()
c_ = c2 // 2 # hidden channels
self.cv1 = Conv(c1, c_, k, s, None, g, act=act)
self.cv2 = Conv(c_, c_, 5, 1, None, c_, act=act)
def forward(self, x):
"""Forward propagation through a Ghost Bottleneck layer with skip connection."""
y = self.cv1(x)
return torch.cat((y, self.cv2(y)), 1)
class RepConv(nn.Module):
"""
RepConv is a basic rep-style block, including training and deploy status. This module is used in RT-DETR.
Based on https://github.com/DingXiaoH/RepVGG/blob/main/repvgg.py
"""
default_act = nn.SiLU() # default activation
def __init__(self, c1, c2, k=3, s=1, p=1, g=1, d=1, act=True, bn=False, deploy=False):
super().__init__()
assert k == 3 and p == 1
self.g = g
self.c1 = c1
self.c2 = c2
self.act = self.default_act if act is True else act if isinstance(act, nn.Module) else nn.Identity()
self.bn = nn.BatchNorm2d(num_features=c1) if bn and c2 == c1 and s == 1 else None
self.conv1 = Conv(c1, c2, k, s, p=p, g=g, act=False)
self.conv2 = Conv(c1, c2, 1, s, p=(p - k // 2), g=g, act=False)
def forward_fuse(self, x):
"""Forward process"""
return self.act(self.conv(x))
def forward(self, x):
"""Forward process"""
id_out = 0 if self.bn is None else self.bn(x)
return self.act(self.conv1(x) + self.conv2(x) + id_out)
def get_equivalent_kernel_bias(self):
kernel3x3, bias3x3 = self._fuse_bn_tensor(self.conv1)
kernel1x1, bias1x1 = self._fuse_bn_tensor(self.conv2)
kernelid, biasid = self._fuse_bn_tensor(self.bn)
return kernel3x3 + self._pad_1x1_to_3x3_tensor(kernel1x1) + kernelid, bias3x3 + bias1x1 + biasid
def _pad_1x1_to_3x3_tensor(self, kernel1x1):
if kernel1x1 is None:
return 0
else:
return torch.nn.functional.pad(kernel1x1, [1, 1, 1, 1])
def _fuse_bn_tensor(self, branch):
if branch is None:
return 0, 0
if isinstance(branch, Conv):
kernel = branch.conv.weight
running_mean = branch.bn.running_mean
running_var = branch.bn.running_var
gamma = branch.bn.weight
beta = branch.bn.bias
eps = branch.bn.eps
elif isinstance(branch, nn.BatchNorm2d):
if not hasattr(self, 'id_tensor'):
input_dim = self.c1 // self.g
kernel_value = np.zeros((self.c1, input_dim, 3, 3), dtype=np.float32)
for i in range(self.c1):
kernel_value[i, i % input_dim, 1, 1] = 1
self.id_tensor = torch.from_numpy(kernel_value).to(branch.weight.device)
kernel = self.id_tensor
running_mean = branch.running_mean
running_var = branch.running_var
gamma = branch.weight
beta = branch.bias
eps = branch.eps
std = (running_var + eps).sqrt()
t = (gamma / std).reshape(-1, 1, 1, 1)
return kernel * t, beta - running_mean * gamma / std
def fuse_convs(self):
if hasattr(self, 'conv'):
return
kernel, bias = self.get_equivalent_kernel_bias()
self.conv = nn.Conv2d(in_channels=self.conv1.conv.in_channels,
out_channels=self.conv1.conv.out_channels,
kernel_size=self.conv1.conv.kernel_size,
stride=self.conv1.conv.stride,
padding=self.conv1.conv.padding,
dilation=self.conv1.conv.dilation,
groups=self.conv1.conv.groups,
bias=True).requires_grad_(False)
self.conv.weight.data = kernel
self.conv.bias.data = bias
for para in self.parameters():
para.detach_()
self.__delattr__('conv1')
self.__delattr__('conv2')
if hasattr(self, 'nm'):
self.__delattr__('nm')
if hasattr(self, 'bn'):
self.__delattr__('bn')
if hasattr(self, 'id_tensor'):
self.__delattr__('id_tensor')
class ChannelAttention(nn.Module):
"""Channel-attention module https://github.com/open-mmlab/mmdetection/tree/v3.0.0rc1/configs/rtmdet."""
def __init__(self, channels: int) -> None:
super().__init__()
self.pool = nn.AdaptiveAvgPool2d(1)
self.fc = nn.Conv2d(channels, channels, 1, 1, 0, bias=True)
self.act = nn.Sigmoid()
def forward(self, x: torch.Tensor) -> torch.Tensor:
return x * self.act(self.fc(self.pool(x)))
class SpatialAttention(nn.Module):
"""Spatial-attention module."""
def __init__(self, kernel_size=7):
"""Initialize Spatial-attention module with kernel size argument."""
super().__init__()
assert kernel_size in (3, 7), 'kernel size must be 3 or 7'
padding = 3 if kernel_size == 7 else 1
self.cv1 = nn.Conv2d(2, 1, kernel_size, padding=padding, bias=False)
self.act = nn.Sigmoid()
def forward(self, x):
"""Apply channel and spatial attention on input for feature recalibration."""
return x * self.act(self.cv1(torch.cat([torch.mean(x, 1, keepdim=True), torch.max(x, 1, keepdim=True)[0]], 1)))
class CBAM(nn.Module):
"""Convolutional Block Attention Module."""
def __init__(self, c1, kernel_size=7): # ch_in, kernels
super().__init__()
self.channel_attention = ChannelAttention(c1)
self.spatial_attention = SpatialAttention(kernel_size)
def forward(self, x):
"""Applies the forward pass through C1 module."""
return self.spatial_attention(self.channel_attention(x))
class Concat(nn.Module):
"""Concatenate a list of tensors along dimension."""
def __init__(self, dimension=1):
"""Concatenates a list of tensors along a specified dimension."""
super().__init__()
self.d = dimension
def forward(self, x):
"""Forward pass for the YOLOv8 mask Proto module."""
return torch.cat(x, self.d)

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# Ultralytics YOLO 🚀, AGPL-3.0 license
"""
Model head modules
"""
import math
import torch
import torch.nn as nn
from torch.nn.init import constant_, xavier_uniform_
from ultralytics.utils.tal import TORCH_1_10, dist2bbox, make_anchors
from .block import DFL, Proto
from .conv import Conv
from .transformer import MLP, DeformableTransformerDecoder, DeformableTransformerDecoderLayer
from .utils import bias_init_with_prob, linear_init_
__all__ = 'Detect', 'Segment', 'Pose', 'Classify', 'RTDETRDecoder'
class Detect(nn.Module):
"""YOLOv8 Detect head for detection models."""
dynamic = False # force grid reconstruction
export = False # export mode
shape = None
anchors = torch.empty(0) # init
strides = torch.empty(0) # init
def __init__(self, nc=80, ch=()): # detection layer
super().__init__()
self.nc = nc # number of classes
self.nl = len(ch) # number of detection layers
self.reg_max = 16 # DFL channels (ch[0] // 16 to scale 4/8/12/16/20 for n/s/m/l/x)
self.no = nc + self.reg_max * 4 # number of outputs per anchor
self.stride = torch.zeros(self.nl) # strides computed during build
c2, c3 = max((16, ch[0] // 4, self.reg_max * 4)), max(ch[0], min(self.nc, 100)) # channels
self.cv2 = nn.ModuleList(
nn.Sequential(Conv(x, c2, 3), Conv(c2, c2, 3), nn.Conv2d(c2, 4 * self.reg_max, 1)) for x in ch)
self.cv3 = nn.ModuleList(nn.Sequential(Conv(x, c3, 3), Conv(c3, c3, 3), nn.Conv2d(c3, self.nc, 1)) for x in ch)
self.dfl = DFL(self.reg_max) if self.reg_max > 1 else nn.Identity()
def forward(self, x):
"""Concatenates and returns predicted bounding boxes and class probabilities."""
shape = x[0].shape # BCHW
for i in range(self.nl):
x[i] = torch.cat((self.cv2[i](x[i]), self.cv3[i](x[i])), 1)
if self.training:
return x
elif self.dynamic or self.shape != shape:
self.anchors, self.strides = (x.transpose(0, 1) for x in make_anchors(x, self.stride, 0.5))
self.shape = shape
x_cat = torch.cat([xi.view(shape[0], self.no, -1) for xi in x], 2)
if self.export and self.format in ('saved_model', 'pb', 'tflite', 'edgetpu', 'tfjs'): # avoid TF FlexSplitV ops
box = x_cat[:, :self.reg_max * 4]
cls = x_cat[:, self.reg_max * 4:]
else:
box, cls = x_cat.split((self.reg_max * 4, self.nc), 1)
dbox = dist2bbox(self.dfl(box), self.anchors.unsqueeze(0), xywh=True, dim=1) * self.strides
if self.export and self.format in ('tflite', 'edgetpu'):
# Normalize xywh with image size to mitigate quantization error of TFLite integer models as done in YOLOv5:
# https://github.com/ultralytics/yolov5/blob/0c8de3fca4a702f8ff5c435e67f378d1fce70243/models/tf.py#L307-L309
# See this PR for details: https://github.com/ultralytics/ultralytics/pull/1695
img_h = shape[2] * self.stride[0]
img_w = shape[3] * self.stride[0]
img_size = torch.tensor([img_w, img_h, img_w, img_h], device=dbox.device).reshape(1, 4, 1)
dbox /= img_size
y = torch.cat((dbox, cls.sigmoid()), 1)
return y if self.export else (y, x)
def bias_init(self):
"""Initialize Detect() biases, WARNING: requires stride availability."""
m = self # self.model[-1] # Detect() module
# cf = torch.bincount(torch.tensor(np.concatenate(dataset.labels, 0)[:, 0]).long(), minlength=nc) + 1
# ncf = math.log(0.6 / (m.nc - 0.999999)) if cf is None else torch.log(cf / cf.sum()) # nominal class frequency
for a, b, s in zip(m.cv2, m.cv3, m.stride): # from
a[-1].bias.data[:] = 1.0 # box
b[-1].bias.data[:m.nc] = math.log(5 / m.nc / (640 / s) ** 2) # cls (.01 objects, 80 classes, 640 img)
class Segment(Detect):
"""YOLOv8 Segment head for segmentation models."""
def __init__(self, nc=80, nm=32, npr=256, ch=()):
"""Initialize the YOLO model attributes such as the number of masks, prototypes, and the convolution layers."""
super().__init__(nc, ch)
self.nm = nm # number of masks
self.npr = npr # number of protos
self.proto = Proto(ch[0], self.npr, self.nm) # protos
self.detect = Detect.forward
c4 = max(ch[0] // 4, self.nm)
self.cv4 = nn.ModuleList(nn.Sequential(Conv(x, c4, 3), Conv(c4, c4, 3), nn.Conv2d(c4, self.nm, 1)) for x in ch)
def forward(self, x):
"""Return model outputs and mask coefficients if training, otherwise return outputs and mask coefficients."""
p = self.proto(x[0]) # mask protos
bs = p.shape[0] # batch size
mc = torch.cat([self.cv4[i](x[i]).view(bs, self.nm, -1) for i in range(self.nl)], 2) # mask coefficients
x = self.detect(self, x)
if self.training:
return x, mc, p
return (torch.cat([x, mc], 1), p) if self.export else (torch.cat([x[0], mc], 1), (x[1], mc, p))
class Pose(Detect):
"""YOLOv8 Pose head for keypoints models."""
def __init__(self, nc=80, kpt_shape=(17, 3), ch=()):
"""Initialize YOLO network with default parameters and Convolutional Layers."""
super().__init__(nc, ch)
self.kpt_shape = kpt_shape # number of keypoints, number of dims (2 for x,y or 3 for x,y,visible)
self.nk = kpt_shape[0] * kpt_shape[1] # number of keypoints total
self.detect = Detect.forward
c4 = max(ch[0] // 4, self.nk)
self.cv4 = nn.ModuleList(nn.Sequential(Conv(x, c4, 3), Conv(c4, c4, 3), nn.Conv2d(c4, self.nk, 1)) for x in ch)
def forward(self, x):
"""Perform forward pass through YOLO model and return predictions."""
bs = x[0].shape[0] # batch size
kpt = torch.cat([self.cv4[i](x[i]).view(bs, self.nk, -1) for i in range(self.nl)], -1) # (bs, 17*3, h*w)
x = self.detect(self, x)
if self.training:
return x, kpt
pred_kpt = self.kpts_decode(bs, kpt)
return torch.cat([x, pred_kpt], 1) if self.export else (torch.cat([x[0], pred_kpt], 1), (x[1], kpt))
def kpts_decode(self, bs, kpts):
"""Decodes keypoints."""
ndim = self.kpt_shape[1]
if self.export: # required for TFLite export to avoid 'PLACEHOLDER_FOR_GREATER_OP_CODES' bug
y = kpts.view(bs, *self.kpt_shape, -1)
a = (y[:, :, :2] * 2.0 + (self.anchors - 0.5)) * self.strides
if ndim == 3:
a = torch.cat((a, y[:, :, 2:3].sigmoid()), 2)
return a.view(bs, self.nk, -1)
else:
y = kpts.clone()
if ndim == 3:
y[:, 2::3].sigmoid_() # inplace sigmoid
y[:, 0::ndim] = (y[:, 0::ndim] * 2.0 + (self.anchors[0] - 0.5)) * self.strides
y[:, 1::ndim] = (y[:, 1::ndim] * 2.0 + (self.anchors[1] - 0.5)) * self.strides
return y
class Classify(nn.Module):
"""YOLOv8 classification head, i.e. x(b,c1,20,20) to x(b,c2)."""
def __init__(self, c1, c2, k=1, s=1, p=None, g=1): # ch_in, ch_out, kernel, stride, padding, groups
super().__init__()
c_ = 1280 # efficientnet_b0 size
self.conv = Conv(c1, c_, k, s, p, g)
self.pool = nn.AdaptiveAvgPool2d(1) # to x(b,c_,1,1)
self.drop = nn.Dropout(p=0.0, inplace=True)
self.linear = nn.Linear(c_, c2) # to x(b,c2)
def forward(self, x):
"""Performs a forward pass of the YOLO model on input image data."""
if isinstance(x, list):
x = torch.cat(x, 1)
x = self.linear(self.drop(self.pool(self.conv(x)).flatten(1)))
return x if self.training else x.softmax(1)
class RTDETRDecoder(nn.Module):
export = False # export mode
def __init__(
self,
nc=80,
ch=(512, 1024, 2048),
hd=256, # hidden dim
nq=300, # num queries
ndp=4, # num decoder points
nh=8, # num head
ndl=6, # num decoder layers
d_ffn=1024, # dim of feedforward
dropout=0.,
act=nn.ReLU(),
eval_idx=-1,
# training args
nd=100, # num denoising
label_noise_ratio=0.5,
box_noise_scale=1.0,
learnt_init_query=False):
super().__init__()
self.hidden_dim = hd
self.nhead = nh
self.nl = len(ch) # num level
self.nc = nc
self.num_queries = nq
self.num_decoder_layers = ndl
# backbone feature projection
self.input_proj = nn.ModuleList(nn.Sequential(nn.Conv2d(x, hd, 1, bias=False), nn.BatchNorm2d(hd)) for x in ch)
# NOTE: simplified version but it's not consistent with .pt weights.
# self.input_proj = nn.ModuleList(Conv(x, hd, act=False) for x in ch)
# Transformer module
decoder_layer = DeformableTransformerDecoderLayer(hd, nh, d_ffn, dropout, act, self.nl, ndp)
self.decoder = DeformableTransformerDecoder(hd, decoder_layer, ndl, eval_idx)
# denoising part
self.denoising_class_embed = nn.Embedding(nc, hd)
self.num_denoising = nd
self.label_noise_ratio = label_noise_ratio
self.box_noise_scale = box_noise_scale
# decoder embedding
self.learnt_init_query = learnt_init_query
if learnt_init_query:
self.tgt_embed = nn.Embedding(nq, hd)
self.query_pos_head = MLP(4, 2 * hd, hd, num_layers=2)
# encoder head
self.enc_output = nn.Sequential(nn.Linear(hd, hd), nn.LayerNorm(hd))
self.enc_score_head = nn.Linear(hd, nc)
self.enc_bbox_head = MLP(hd, hd, 4, num_layers=3)
# decoder head
self.dec_score_head = nn.ModuleList([nn.Linear(hd, nc) for _ in range(ndl)])
self.dec_bbox_head = nn.ModuleList([MLP(hd, hd, 4, num_layers=3) for _ in range(ndl)])
self._reset_parameters()
def forward(self, x, batch=None):
from ultralytics.models.utils.ops import get_cdn_group
# input projection and embedding
feats, shapes = self._get_encoder_input(x)
# prepare denoising training
dn_embed, dn_bbox, attn_mask, dn_meta = \
get_cdn_group(batch,
self.nc,
self.num_queries,
self.denoising_class_embed.weight,
self.num_denoising,
self.label_noise_ratio,
self.box_noise_scale,
self.training)
embed, refer_bbox, enc_bboxes, enc_scores = \
self._get_decoder_input(feats, shapes, dn_embed, dn_bbox)
# decoder
dec_bboxes, dec_scores = self.decoder(embed,
refer_bbox,
feats,
shapes,
self.dec_bbox_head,
self.dec_score_head,
self.query_pos_head,
attn_mask=attn_mask)
x = dec_bboxes, dec_scores, enc_bboxes, enc_scores, dn_meta
if self.training:
return x
# (bs, 300, 4+nc)
y = torch.cat((dec_bboxes.squeeze(0), dec_scores.squeeze(0).sigmoid()), -1)
return y if self.export else (y, x)
def _generate_anchors(self, shapes, grid_size=0.05, dtype=torch.float32, device='cpu', eps=1e-2):
anchors = []
for i, (h, w) in enumerate(shapes):
sy = torch.arange(end=h, dtype=dtype, device=device)
sx = torch.arange(end=w, dtype=dtype, device=device)
grid_y, grid_x = torch.meshgrid(sy, sx, indexing='ij') if TORCH_1_10 else torch.meshgrid(sy, sx)
grid_xy = torch.stack([grid_x, grid_y], -1) # (h, w, 2)
valid_WH = torch.tensor([h, w], dtype=dtype, device=device)
grid_xy = (grid_xy.unsqueeze(0) + 0.5) / valid_WH # (1, h, w, 2)
wh = torch.ones_like(grid_xy, dtype=dtype, device=device) * grid_size * (2.0 ** i)
anchors.append(torch.cat([grid_xy, wh], -1).view(-1, h * w, 4)) # (1, h*w, 4)
anchors = torch.cat(anchors, 1) # (1, h*w*nl, 4)
valid_mask = ((anchors > eps) * (anchors < 1 - eps)).all(-1, keepdim=True) # 1, h*w*nl, 1
anchors = torch.log(anchors / (1 - anchors))
anchors = anchors.masked_fill(~valid_mask, float('inf'))
return anchors, valid_mask
def _get_encoder_input(self, x):
# get projection features
x = [self.input_proj[i](feat) for i, feat in enumerate(x)]
# get encoder inputs
feats = []
shapes = []
for feat in x:
h, w = feat.shape[2:]
# [b, c, h, w] -> [b, h*w, c]
feats.append(feat.flatten(2).permute(0, 2, 1))
# [nl, 2]
shapes.append([h, w])
# [b, h*w, c]
feats = torch.cat(feats, 1)
return feats, shapes
def _get_decoder_input(self, feats, shapes, dn_embed=None, dn_bbox=None):
bs = len(feats)
# prepare input for decoder
anchors, valid_mask = self._generate_anchors(shapes, dtype=feats.dtype, device=feats.device)
features = self.enc_output(valid_mask * feats) # bs, h*w, 256
enc_outputs_scores = self.enc_score_head(features) # (bs, h*w, nc)
# query selection
# (bs, num_queries)
topk_ind = torch.topk(enc_outputs_scores.max(-1).values, self.num_queries, dim=1).indices.view(-1)
# (bs, num_queries)
batch_ind = torch.arange(end=bs, dtype=topk_ind.dtype).unsqueeze(-1).repeat(1, self.num_queries).view(-1)
# (bs, num_queries, 256)
top_k_features = features[batch_ind, topk_ind].view(bs, self.num_queries, -1)
# (bs, num_queries, 4)
top_k_anchors = anchors[:, topk_ind].view(bs, self.num_queries, -1)
# dynamic anchors + static content
refer_bbox = self.enc_bbox_head(top_k_features) + top_k_anchors
enc_bboxes = refer_bbox.sigmoid()
if dn_bbox is not None:
refer_bbox = torch.cat([dn_bbox, refer_bbox], 1)
enc_scores = enc_outputs_scores[batch_ind, topk_ind].view(bs, self.num_queries, -1)
embeddings = self.tgt_embed.weight.unsqueeze(0).repeat(bs, 1, 1) if self.learnt_init_query else top_k_features
if self.training:
refer_bbox = refer_bbox.detach()
if not self.learnt_init_query:
embeddings = embeddings.detach()
if dn_embed is not None:
embeddings = torch.cat([dn_embed, embeddings], 1)
return embeddings, refer_bbox, enc_bboxes, enc_scores
# TODO
def _reset_parameters(self):
# class and bbox head init
bias_cls = bias_init_with_prob(0.01) / 80 * self.nc
# NOTE: the weight initialization in `linear_init_` would cause NaN when training with custom datasets.
# linear_init_(self.enc_score_head)
constant_(self.enc_score_head.bias, bias_cls)
constant_(self.enc_bbox_head.layers[-1].weight, 0.)
constant_(self.enc_bbox_head.layers[-1].bias, 0.)
for cls_, reg_ in zip(self.dec_score_head, self.dec_bbox_head):
# linear_init_(cls_)
constant_(cls_.bias, bias_cls)
constant_(reg_.layers[-1].weight, 0.)
constant_(reg_.layers[-1].bias, 0.)
linear_init_(self.enc_output[0])
xavier_uniform_(self.enc_output[0].weight)
if self.learnt_init_query:
xavier_uniform_(self.tgt_embed.weight)
xavier_uniform_(self.query_pos_head.layers[0].weight)
xavier_uniform_(self.query_pos_head.layers[1].weight)
for layer in self.input_proj:
xavier_uniform_(layer[0].weight)

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# Ultralytics YOLO 🚀, AGPL-3.0 license
"""
Transformer modules
"""
import math
import torch
import torch.nn as nn
import torch.nn.functional as F
from torch.nn.init import constant_, xavier_uniform_
from .conv import Conv
from .utils import _get_clones, inverse_sigmoid, multi_scale_deformable_attn_pytorch
__all__ = ('TransformerEncoderLayer', 'TransformerLayer', 'TransformerBlock', 'MLPBlock', 'LayerNorm2d', 'AIFI',
'DeformableTransformerDecoder', 'DeformableTransformerDecoderLayer', 'MSDeformAttn', 'MLP')
class TransformerEncoderLayer(nn.Module):
"""Transformer Encoder."""
def __init__(self, c1, cm=2048, num_heads=8, dropout=0.0, act=nn.GELU(), normalize_before=False):
super().__init__()
from ...utils.torch_utils import TORCH_1_9
if not TORCH_1_9:
raise ModuleNotFoundError(
'TransformerEncoderLayer() requires torch>=1.9 to use nn.MultiheadAttention(batch_first=True).')
self.ma = nn.MultiheadAttention(c1, num_heads, dropout=dropout, batch_first=True)
# Implementation of Feedforward model
self.fc1 = nn.Linear(c1, cm)
self.fc2 = nn.Linear(cm, c1)
self.norm1 = nn.LayerNorm(c1)
self.norm2 = nn.LayerNorm(c1)
self.dropout = nn.Dropout(dropout)
self.dropout1 = nn.Dropout(dropout)
self.dropout2 = nn.Dropout(dropout)
self.act = act
self.normalize_before = normalize_before
def with_pos_embed(self, tensor, pos=None):
"""Add position embeddings if given."""
return tensor if pos is None else tensor + pos
def forward_post(self, src, src_mask=None, src_key_padding_mask=None, pos=None):
q = k = self.with_pos_embed(src, pos)
src2 = self.ma(q, k, value=src, attn_mask=src_mask, key_padding_mask=src_key_padding_mask)[0]
src = src + self.dropout1(src2)
src = self.norm1(src)
src2 = self.fc2(self.dropout(self.act(self.fc1(src))))
src = src + self.dropout2(src2)
return self.norm2(src)
def forward_pre(self, src, src_mask=None, src_key_padding_mask=None, pos=None):
src2 = self.norm1(src)
q = k = self.with_pos_embed(src2, pos)
src2 = self.ma(q, k, value=src2, attn_mask=src_mask, key_padding_mask=src_key_padding_mask)[0]
src = src + self.dropout1(src2)
src2 = self.norm2(src)
src2 = self.fc2(self.dropout(self.act(self.fc1(src2))))
return src + self.dropout2(src2)
def forward(self, src, src_mask=None, src_key_padding_mask=None, pos=None):
"""Forward propagates the input through the encoder module."""
if self.normalize_before:
return self.forward_pre(src, src_mask, src_key_padding_mask, pos)
return self.forward_post(src, src_mask, src_key_padding_mask, pos)
class AIFI(TransformerEncoderLayer):
def __init__(self, c1, cm=2048, num_heads=8, dropout=0, act=nn.GELU(), normalize_before=False):
super().__init__(c1, cm, num_heads, dropout, act, normalize_before)
def forward(self, x):
c, h, w = x.shape[1:]
pos_embed = self.build_2d_sincos_position_embedding(w, h, c)
# flatten [B, C, H, W] to [B, HxW, C]
x = super().forward(x.flatten(2).permute(0, 2, 1), pos=pos_embed.to(device=x.device, dtype=x.dtype))
return x.permute(0, 2, 1).view([-1, c, h, w]).contiguous()
@staticmethod
def build_2d_sincos_position_embedding(w, h, embed_dim=256, temperature=10000.):
grid_w = torch.arange(int(w), dtype=torch.float32)
grid_h = torch.arange(int(h), dtype=torch.float32)
grid_w, grid_h = torch.meshgrid(grid_w, grid_h, indexing='ij')
assert embed_dim % 4 == 0, \
'Embed dimension must be divisible by 4 for 2D sin-cos position embedding'
pos_dim = embed_dim // 4
omega = torch.arange(pos_dim, dtype=torch.float32) / pos_dim
omega = 1. / (temperature ** omega)
out_w = grid_w.flatten()[..., None] @ omega[None]
out_h = grid_h.flatten()[..., None] @ omega[None]
return torch.cat([torch.sin(out_w), torch.cos(out_w), torch.sin(out_h), torch.cos(out_h)], 1)[None]
class TransformerLayer(nn.Module):
"""Transformer layer https://arxiv.org/abs/2010.11929 (LayerNorm layers removed for better performance)."""
def __init__(self, c, num_heads):
"""Initializes a self-attention mechanism using linear transformations and multi-head attention."""
super().__init__()
self.q = nn.Linear(c, c, bias=False)
self.k = nn.Linear(c, c, bias=False)
self.v = nn.Linear(c, c, bias=False)
self.ma = nn.MultiheadAttention(embed_dim=c, num_heads=num_heads)
self.fc1 = nn.Linear(c, c, bias=False)
self.fc2 = nn.Linear(c, c, bias=False)
def forward(self, x):
"""Apply a transformer block to the input x and return the output."""
x = self.ma(self.q(x), self.k(x), self.v(x))[0] + x
return self.fc2(self.fc1(x)) + x
class TransformerBlock(nn.Module):
"""Vision Transformer https://arxiv.org/abs/2010.11929."""
def __init__(self, c1, c2, num_heads, num_layers):
"""Initialize a Transformer module with position embedding and specified number of heads and layers."""
super().__init__()
self.conv = None
if c1 != c2:
self.conv = Conv(c1, c2)
self.linear = nn.Linear(c2, c2) # learnable position embedding
self.tr = nn.Sequential(*(TransformerLayer(c2, num_heads) for _ in range(num_layers)))
self.c2 = c2
def forward(self, x):
"""Forward propagates the input through the bottleneck module."""
if self.conv is not None:
x = self.conv(x)
b, _, w, h = x.shape
p = x.flatten(2).permute(2, 0, 1)
return self.tr(p + self.linear(p)).permute(1, 2, 0).reshape(b, self.c2, w, h)
class MLPBlock(nn.Module):
def __init__(self, embedding_dim, mlp_dim, act=nn.GELU):
super().__init__()
self.lin1 = nn.Linear(embedding_dim, mlp_dim)
self.lin2 = nn.Linear(mlp_dim, embedding_dim)
self.act = act()
def forward(self, x: torch.Tensor) -> torch.Tensor:
return self.lin2(self.act(self.lin1(x)))
class MLP(nn.Module):
""" Very simple multi-layer perceptron (also called FFN)"""
def __init__(self, input_dim, hidden_dim, output_dim, num_layers):
super().__init__()
self.num_layers = num_layers
h = [hidden_dim] * (num_layers - 1)
self.layers = nn.ModuleList(nn.Linear(n, k) for n, k in zip([input_dim] + h, h + [output_dim]))
def forward(self, x):
for i, layer in enumerate(self.layers):
x = F.relu(layer(x)) if i < self.num_layers - 1 else layer(x)
return x
class LayerNorm2d(nn.Module):
"""
LayerNorm2d module from https://github.com/facebookresearch/detectron2/blob/main/detectron2/layers/batch_norm.py
https://github.com/facebookresearch/ConvNeXt/blob/d1fa8f6fef0a165b27399986cc2bdacc92777e40/models/convnext.py#L119
"""
def __init__(self, num_channels, eps=1e-6):
super().__init__()
self.weight = nn.Parameter(torch.ones(num_channels))
self.bias = nn.Parameter(torch.zeros(num_channels))
self.eps = eps
def forward(self, x):
u = x.mean(1, keepdim=True)
s = (x - u).pow(2).mean(1, keepdim=True)
x = (x - u) / torch.sqrt(s + self.eps)
return self.weight[:, None, None] * x + self.bias[:, None, None]
class MSDeformAttn(nn.Module):
"""
Original Multi-Scale Deformable Attention Module.
https://github.com/fundamentalvision/Deformable-DETR/blob/main/models/ops/modules/ms_deform_attn.py
"""
def __init__(self, d_model=256, n_levels=4, n_heads=8, n_points=4):
super().__init__()
if d_model % n_heads != 0:
raise ValueError(f'd_model must be divisible by n_heads, but got {d_model} and {n_heads}')
_d_per_head = d_model // n_heads
# you'd better set _d_per_head to a power of 2 which is more efficient in our CUDA implementation
assert _d_per_head * n_heads == d_model, '`d_model` must be divisible by `n_heads`'
self.im2col_step = 64
self.d_model = d_model
self.n_levels = n_levels
self.n_heads = n_heads
self.n_points = n_points
self.sampling_offsets = nn.Linear(d_model, n_heads * n_levels * n_points * 2)
self.attention_weights = nn.Linear(d_model, n_heads * n_levels * n_points)
self.value_proj = nn.Linear(d_model, d_model)
self.output_proj = nn.Linear(d_model, d_model)
self._reset_parameters()
def _reset_parameters(self):
constant_(self.sampling_offsets.weight.data, 0.)
thetas = torch.arange(self.n_heads, dtype=torch.float32) * (2.0 * math.pi / self.n_heads)
grid_init = torch.stack([thetas.cos(), thetas.sin()], -1)
grid_init = (grid_init / grid_init.abs().max(-1, keepdim=True)[0]).view(self.n_heads, 1, 1, 2).repeat(
1, self.n_levels, self.n_points, 1)
for i in range(self.n_points):
grid_init[:, :, i, :] *= i + 1
with torch.no_grad():
self.sampling_offsets.bias = nn.Parameter(grid_init.view(-1))
constant_(self.attention_weights.weight.data, 0.)
constant_(self.attention_weights.bias.data, 0.)
xavier_uniform_(self.value_proj.weight.data)
constant_(self.value_proj.bias.data, 0.)
xavier_uniform_(self.output_proj.weight.data)
constant_(self.output_proj.bias.data, 0.)
def forward(self, query, refer_bbox, value, value_shapes, value_mask=None):
"""
https://github.com/PaddlePaddle/PaddleDetection/blob/develop/ppdet/modeling/transformers/deformable_transformer.py
Args:
query (torch.Tensor): [bs, query_length, C]
refer_bbox (torch.Tensor): [bs, query_length, n_levels, 2], range in [0, 1], top-left (0,0),
bottom-right (1, 1), including padding area
value (torch.Tensor): [bs, value_length, C]
value_shapes (List): [n_levels, 2], [(H_0, W_0), (H_1, W_1), ..., (H_{L-1}, W_{L-1})]
value_mask (Tensor): [bs, value_length], True for non-padding elements, False for padding elements
Returns:
output (Tensor): [bs, Length_{query}, C]
"""
bs, len_q = query.shape[:2]
len_v = value.shape[1]
assert sum(s[0] * s[1] for s in value_shapes) == len_v
value = self.value_proj(value)
if value_mask is not None:
value = value.masked_fill(value_mask[..., None], float(0))
value = value.view(bs, len_v, self.n_heads, self.d_model // self.n_heads)
sampling_offsets = self.sampling_offsets(query).view(bs, len_q, self.n_heads, self.n_levels, self.n_points, 2)
attention_weights = self.attention_weights(query).view(bs, len_q, self.n_heads, self.n_levels * self.n_points)
attention_weights = F.softmax(attention_weights, -1).view(bs, len_q, self.n_heads, self.n_levels, self.n_points)
# N, Len_q, n_heads, n_levels, n_points, 2
num_points = refer_bbox.shape[-1]
if num_points == 2:
offset_normalizer = torch.as_tensor(value_shapes, dtype=query.dtype, device=query.device).flip(-1)
add = sampling_offsets / offset_normalizer[None, None, None, :, None, :]
sampling_locations = refer_bbox[:, :, None, :, None, :] + add
elif num_points == 4:
add = sampling_offsets / self.n_points * refer_bbox[:, :, None, :, None, 2:] * 0.5
sampling_locations = refer_bbox[:, :, None, :, None, :2] + add
else:
raise ValueError(f'Last dim of reference_points must be 2 or 4, but got {num_points}.')
output = multi_scale_deformable_attn_pytorch(value, value_shapes, sampling_locations, attention_weights)
return self.output_proj(output)
class DeformableTransformerDecoderLayer(nn.Module):
"""
https://github.com/PaddlePaddle/PaddleDetection/blob/develop/ppdet/modeling/transformers/deformable_transformer.py
https://github.com/fundamentalvision/Deformable-DETR/blob/main/models/deformable_transformer.py
"""
def __init__(self, d_model=256, n_heads=8, d_ffn=1024, dropout=0., act=nn.ReLU(), n_levels=4, n_points=4):
super().__init__()
# self attention
self.self_attn = nn.MultiheadAttention(d_model, n_heads, dropout=dropout)
self.dropout1 = nn.Dropout(dropout)
self.norm1 = nn.LayerNorm(d_model)
# cross attention
self.cross_attn = MSDeformAttn(d_model, n_levels, n_heads, n_points)
self.dropout2 = nn.Dropout(dropout)
self.norm2 = nn.LayerNorm(d_model)
# ffn
self.linear1 = nn.Linear(d_model, d_ffn)
self.act = act
self.dropout3 = nn.Dropout(dropout)
self.linear2 = nn.Linear(d_ffn, d_model)
self.dropout4 = nn.Dropout(dropout)
self.norm3 = nn.LayerNorm(d_model)
@staticmethod
def with_pos_embed(tensor, pos):
return tensor if pos is None else tensor + pos
def forward_ffn(self, tgt):
tgt2 = self.linear2(self.dropout3(self.act(self.linear1(tgt))))
tgt = tgt + self.dropout4(tgt2)
return self.norm3(tgt)
def forward(self, embed, refer_bbox, feats, shapes, padding_mask=None, attn_mask=None, query_pos=None):
# self attention
q = k = self.with_pos_embed(embed, query_pos)
tgt = self.self_attn(q.transpose(0, 1), k.transpose(0, 1), embed.transpose(0, 1),
attn_mask=attn_mask)[0].transpose(0, 1)
embed = embed + self.dropout1(tgt)
embed = self.norm1(embed)
# cross attention
tgt = self.cross_attn(self.with_pos_embed(embed, query_pos), refer_bbox.unsqueeze(2), feats, shapes,
padding_mask)
embed = embed + self.dropout2(tgt)
embed = self.norm2(embed)
# ffn
return self.forward_ffn(embed)
class DeformableTransformerDecoder(nn.Module):
"""
https://github.com/PaddlePaddle/PaddleDetection/blob/develop/ppdet/modeling/transformers/deformable_transformer.py
"""
def __init__(self, hidden_dim, decoder_layer, num_layers, eval_idx=-1):
super().__init__()
self.layers = _get_clones(decoder_layer, num_layers)
self.num_layers = num_layers
self.hidden_dim = hidden_dim
self.eval_idx = eval_idx if eval_idx >= 0 else num_layers + eval_idx
def forward(
self,
embed, # decoder embeddings
refer_bbox, # anchor
feats, # image features
shapes, # feature shapes
bbox_head,
score_head,
pos_mlp,
attn_mask=None,
padding_mask=None):
output = embed
dec_bboxes = []
dec_cls = []
last_refined_bbox = None
refer_bbox = refer_bbox.sigmoid()
for i, layer in enumerate(self.layers):
output = layer(output, refer_bbox, feats, shapes, padding_mask, attn_mask, pos_mlp(refer_bbox))
bbox = bbox_head[i](output)
refined_bbox = torch.sigmoid(bbox + inverse_sigmoid(refer_bbox))
if self.training:
dec_cls.append(score_head[i](output))
if i == 0:
dec_bboxes.append(refined_bbox)
else:
dec_bboxes.append(torch.sigmoid(bbox + inverse_sigmoid(last_refined_bbox)))
elif i == self.eval_idx:
dec_cls.append(score_head[i](output))
dec_bboxes.append(refined_bbox)
break
last_refined_bbox = refined_bbox
refer_bbox = refined_bbox.detach() if self.training else refined_bbox
return torch.stack(dec_bboxes), torch.stack(dec_cls)

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# Ultralytics YOLO 🚀, AGPL-3.0 license
"""
Module utils
"""
import copy
import math
import numpy as np
import torch
import torch.nn as nn
import torch.nn.functional as F
from torch.nn.init import uniform_
__all__ = 'multi_scale_deformable_attn_pytorch', 'inverse_sigmoid'
def _get_clones(module, n):
return nn.ModuleList([copy.deepcopy(module) for _ in range(n)])
def bias_init_with_prob(prior_prob=0.01):
"""initialize conv/fc bias value according to a given probability value."""
return float(-np.log((1 - prior_prob) / prior_prob)) # return bias_init
def linear_init_(module):
bound = 1 / math.sqrt(module.weight.shape[0])
uniform_(module.weight, -bound, bound)
if hasattr(module, 'bias') and module.bias is not None:
uniform_(module.bias, -bound, bound)
def inverse_sigmoid(x, eps=1e-5):
x = x.clamp(min=0, max=1)
x1 = x.clamp(min=eps)
x2 = (1 - x).clamp(min=eps)
return torch.log(x1 / x2)
def multi_scale_deformable_attn_pytorch(value: torch.Tensor, value_spatial_shapes: torch.Tensor,
sampling_locations: torch.Tensor,
attention_weights: torch.Tensor) -> torch.Tensor:
"""
Multi-scale deformable attention.
https://github.com/IDEA-Research/detrex/blob/main/detrex/layers/multi_scale_deform_attn.py
"""
bs, _, num_heads, embed_dims = value.shape
_, num_queries, num_heads, num_levels, num_points, _ = sampling_locations.shape
value_list = value.split([H_ * W_ for H_, W_ in value_spatial_shapes], dim=1)
sampling_grids = 2 * sampling_locations - 1
sampling_value_list = []
for level, (H_, W_) in enumerate(value_spatial_shapes):
# bs, H_*W_, num_heads, embed_dims ->
# bs, H_*W_, num_heads*embed_dims ->
# bs, num_heads*embed_dims, H_*W_ ->
# bs*num_heads, embed_dims, H_, W_
value_l_ = (value_list[level].flatten(2).transpose(1, 2).reshape(bs * num_heads, embed_dims, H_, W_))
# bs, num_queries, num_heads, num_points, 2 ->
# bs, num_heads, num_queries, num_points, 2 ->
# bs*num_heads, num_queries, num_points, 2
sampling_grid_l_ = sampling_grids[:, :, :, level].transpose(1, 2).flatten(0, 1)
# bs*num_heads, embed_dims, num_queries, num_points
sampling_value_l_ = F.grid_sample(value_l_,
sampling_grid_l_,
mode='bilinear',
padding_mode='zeros',
align_corners=False)
sampling_value_list.append(sampling_value_l_)
# (bs, num_queries, num_heads, num_levels, num_points) ->
# (bs, num_heads, num_queries, num_levels, num_points) ->
# (bs, num_heads, 1, num_queries, num_levels*num_points)
attention_weights = attention_weights.transpose(1, 2).reshape(bs * num_heads, 1, num_queries,
num_levels * num_points)
output = ((torch.stack(sampling_value_list, dim=-2).flatten(-2) * attention_weights).sum(-1).view(
bs, num_heads * embed_dims, num_queries))
return output.transpose(1, 2).contiguous()