RT-DETR改进策略【卷积层】| CVPR-2024 利用DynamicConv 动态卷积 结合ResNetLayer进行二次创新,提高精度
一、本文介绍
本文记录的是
利用
DynamicConv
优化
RT-DETR
的目标检测网络模型
。 在大规模训练中,模型的参数数量越多,FLOP也越高,但在一些对计算资源有限制的场景下,需要低FLOP的模型同时又希望模型能从大规模预训练中受益。
传统的方法很难在增加参数的同时保持低FLOP
,因此
Dynamic convolution模块
应运而生。本文详细研究了
Dynamic convolution模块
的运行原理,并将其加入到RT-DETR中进行二次创新。
二、动态卷积介绍
2.1 设计出发点
- 在大规模视觉预训练中,通常模型的性能受到数据、参数和FLOP三个关键因素的影响。一般来说,模型的参数数量越多,FLOP也越高,但在移动设备等对计算资源有限制的场景下,需要低FLOP的模型同时又希望模型能从大规模预训练中受益。传统的方法很难在增加参数的同时保持低FLOP,因此需要一种新的设计来解决这个问题, Dynamic convolution 模块应运而生。
2.2 原理
-
Dynamic convolution模块基于动态系数生成的原理来工作。对于输入 X X X ,首先应用全局平均池化将信息融合成一个向量,然后使用一个两层的带有softmax激活的MLP模块来动态地产生系数 α \alpha α ,即 α = s o f t m a x ( M L P ( P o o l ( X ) ) ) \alpha = softmax(MLP(Pool(X))) α = so f t ma x ( M L P ( P oo l ( X ))) ,这里 α ∈ R M \alpha \in \mathbb{R}^{M} α ∈ R M 。 -
Dynamic convolution的计算可以表示为 Y = X ∗ W ′ Y = X * W' Y = X ∗ W ′ ,其中 W ′ = ∑ i = 1 M α i W i W'=\sum_{i = 1}^{M} \alpha_{i} W_{i} W ′ = ∑ i = 1 M α i W i , W i ∈ R C o u t × C i n × H × W W_{i} \in \mathbb{R}^{C_{out } ×C_{in } ×H ×W} W i ∈ R C o u t × C in × H × W 是第 i i i 个卷积权重张量, α i \alpha_{i} α i 是对应的动态系数。系数 α i \alpha_{i} α i 是根据不同的输入样本动态生成的。
2.3 结构
- 系数生成模块 :具有 C i n C_{in} C in 隐藏维度,该模块需要 C i n 2 + C i n M C_{in}^{2}+C_{in}M C in 2 + C in M 个参数以及 C i n 2 + C i n M C_{in}^{2}+C_{in}M C in 2 + C in M 个FLOP。
- 动态权重融合模块 :此模块是无参数的,具有 M ⋅ C o u t ⋅ C i n ⋅ K ⋅ K M \cdot C_{out } \cdot C_{in } \cdot K \cdot K M ⋅ C o u t ⋅ C in ⋅ K ⋅ K 个FLOP。
- 卷积过程模块 :与常规卷积类似,但权重是动态融合后的结果。
动态卷积的FLOP增加量相对标准卷积来说可忽略不计。其FLOP比例 R f l o p s R_{flops} R f l o p s 在 1 < M ≪ H ′ W ′ , C i n ≈ C o u t 1<M \ll H'W', C_{in } \approx C_{out } 1 < M ≪ H ′ W ′ , C in ≈ C o u t 的条件下约等于 1 1 1 ,即相比于标准卷积,它在引入更多参数的同时几乎没有带来额外的FLOP。这使得模型在增加参数以更好地从大规模预训练中受益的同时,不会因FLOP的大幅增加而难以在计算资源受限的设备上运行。
论文: https://arxiv.org/pdf/2306.14525
源码: https://github.com/huawei-noah/Efficient-AI-Backbones
三、DynamicConv的实现代码
DynamicConv模块
的实现代码如下:
import math
from functools import partial
import torch
import torch.nn as nn
import torch.nn.functional as F
from timm.layers import drop_path, SqueezeExcite
from timm.models.layers import CondConv2d, hard_sigmoid, DropPath
from ultralytics.nn.modules.conv import LightConv
class DynamicConv(nn.Module):
""" Dynamic Conv layer
"""
def __init__(self, in_features, out_features, kernel_size=1, stride=1, padding='', dilation=1,
groups=1, bias=False, num_experts=4):
super().__init__()
self.routing = nn.Linear(in_features, num_experts)
self.cond_conv = CondConv2d(in_features, out_features, kernel_size, stride, padding, dilation,
groups, bias, num_experts)
def forward(self, x):
pooled_inputs = F.adaptive_avg_pool2d(x, 1).flatten(1) # CondConv routing
routing_weights = torch.sigmoid(self.routing(pooled_inputs))
x = self.cond_conv(x, routing_weights)
return x
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 ResNetBlock(nn.Module):
"""ResNet block with standard convolution layers."""
def __init__(self, c1, c2, s=1, e=4):
"""Initialize convolution with given parameters."""
super().__init__()
c3 = e * c2
self.cv1 = DynamicConv(c1, c2)
self.cv2 = Conv(c2, c2, k=3, s=s, p=1, act=True)
self.cv3 = Conv(c2, c3, k=1, act=False)
self.shortcut = nn.Sequential(Conv(c1, c3, k=1, s=s, act=False)) if s != 1 or c1 != c3 else nn.Identity()
def forward(self, x):
"""Forward pass through the ResNet block."""
return F.relu(self.cv3(self.cv2(self.cv1(x))) + self.shortcut(x))
class ResNetLayer_DynamicConv(nn.Module):
"""ResNet layer with multiple ResNet blocks."""
def __init__(self, c1, c2, s=1, is_first=False, n=1, e=4):
"""Initializes the ResNetLayer given arguments."""
super().__init__()
self.is_first = is_first
if self.is_first:
self.layer = nn.Sequential(
Conv(c1, c2, k=7, s=2, p=3, act=True), nn.MaxPool2d(kernel_size=3, stride=2, padding=1)
)
else:
blocks = [ResNetBlock(c1, c2, s, e=e)]
blocks.extend([ResNetBlock(e * c2, c2, 1, e=e) for _ in range(n - 1)])
self.layer = nn.Sequential(*blocks)
def forward(self, x):
"""Forward pass through the ResNet layer."""
return self.layer(x)
四、创新模块
4.1 改进点1⭐
模块改进方法
:直接加入
DynamicConv模块
(
第五节讲解添加步骤
)。
DynamicConv模块
添加后如下:
4.2 改进点2⭐
模块改进方法
:基于
DynamicConv模块
的
ResNetLayer
(
第五节讲解添加步骤
)。
第二种改进方法是对
RT-DETR
中的
ResNetLayer模块
进行改进,并将
DynamicConv
在加入到
ResNetLayer
模块中。
改进代码如下:
首先添加如下代码改进
ResNetBlock
模块,并
ResNetLayer
重命名为
ResNetLayer_RFAConv
class ResNetBlock(nn.Module):
"""ResNet block with standard convolution layers."""
def __init__(self, c1, c2, s=1, e=4):
"""Initialize convolution with given parameters."""
super().__init__()
c3 = e * c2
self.cv1 = DynamicConv(c1, c2)
self.cv2 = Conv(c2, c2, k=3, s=s, p=1, act=True)
self.cv3 = Conv(c2, c3, k=1, act=False)
self.shortcut = nn.Sequential(Conv(c1, c3, k=1, s=s, act=False)) if s != 1 or c1 != c3 else nn.Identity()
def forward(self, x):
"""Forward pass through the ResNet block."""
return F.relu(self.cv3(self.cv2(self.cv1(x))) + self.shortcut(x))
class ResNetLayer_DynamicConv(nn.Module):
"""ResNet layer with multiple ResNet blocks."""
def __init__(self, c1, c2, s=1, is_first=False, n=1, e=4):
"""Initializes the ResNetLayer given arguments."""
super().__init__()
self.is_first = is_first
if self.is_first:
self.layer = nn.Sequential(
Conv(c1, c2, k=7, s=2, p=3, act=True), nn.MaxPool2d(kernel_size=3, stride=2, padding=1)
)
else:
blocks = [ResNetBlock(c1, c2, s, e=e)]
blocks.extend([ResNetBlock(e * c2, c2, 1, e=e) for _ in range(n - 1)])
self.layer = nn.Sequential(*blocks)
def forward(self, x):
"""Forward pass through the ResNet layer."""
return self.layer(x)
注意❗:在
第五小节
中需要声明的模块名称为:
DynamicConv
和
ResNetLayer_DynamicConv
。
五、添加步骤
5.1 修改一
① 在
ultralytics/nn/
目录下新建
AddModules
文件夹用于存放模块代码
② 在
AddModules
文件夹下新建
DynamicConv.py
,将
第三节
中的代码粘贴到此处
5.2 修改二
在
AddModules
文件夹下新建
__init__.py
(已有则不用新建),在文件内导入模块:
from .DynamicConv import *
5.3 修改三
在
ultralytics/nn/modules/tasks.py
文件中,需要在两处位置添加各模块类名称。
首先:导入模块
其次:在
parse_model函数
中注册
DynamicConv
和
ResNetLayer_DynamicConv
模块
六、yaml模型文件
6.1 模型改进版本1
此处以
ultralytics/cfg/models/rt-detr/rtdetr-l.yaml
为例,在同目录下创建一个用于自己数据集训练的模型文件
rtdetr-l-DynamicConv.yaml
。
将
rtdetr-l.yaml
中的内容复制到
rtdetr-l-DynamicConv.yaml
文件下,修改
nc
数量等于自己数据中目标的数量。
📌 模型的修改方法是将
骨干网络
中添加
DynamicConv模块
。
# Ultralytics YOLO 🚀, AGPL-3.0 license
# RT-DETR-l object detection model with P3-P5 outputs. For details see https://docs.ultralytics.com/models/rtdetr
# Parameters
nc: 1 # number of classes
scales: # model compound scaling constants, i.e. 'model=yolov8n-cls.yaml' will call yolov8-cls.yaml with scale 'n'
# [depth, width, max_channels]
l: [1.00, 1.00, 1024]
backbone:
# [from, repeats, module, args]
- [-1, 1, HGStem, [32, 48]] # 0-P2/4
- [-1, 6, HGBlock, [48, 128, 3]] # stage 1
- [-1, 1, DWConv, [128, 3, 2, 1, False]] # 2-P3/8
- [-1, 6, HGBlock, [96, 512, 3]] # stage 2
- [-1, 1, DWConv, [512, 3, 2, 1, False]] # 4-P4/16
- [-1, 6, DynamicConv, [512]] # cm, c2, k, light, shortcut
- [-1, 6, DynamicConv, [512]]
- [-1, 6, DynamicConv, [512]] # stage 3
- [-1, 1, DWConv, [1024, 3, 2, 1, False]] # 8-P5/32
- [-1, 6, HGBlock, [384, 2048, 5, True, False]] # stage 4
head:
- [-1, 1, Conv, [256, 1, 1, None, 1, 1, False]] # 10 input_proj.2
- [-1, 1, AIFI, [1024, 8]]
- [-1, 1, Conv, [256, 1, 1]] # 12, Y5, lateral_convs.0
- [-1, 1, nn.Upsample, [None, 2, "nearest"]]
- [7, 1, Conv, [256, 1, 1, None, 1, 1, False]] # 14 input_proj.1
- [[-2, -1], 1, Concat, [1]]
- [-1, 3, RepC3, [256]] # 16, fpn_blocks.0
- [-1, 1, Conv, [256, 1, 1]] # 17, Y4, lateral_convs.1
- [-1, 1, nn.Upsample, [None, 2, "nearest"]]
- [3, 1, Conv, [256, 1, 1, None, 1, 1, False]] # 19 input_proj.0
- [[-2, -1], 1, Concat, [1]] # cat backbone P4
- [-1, 3, RepC3, [256]] # X3 (21), fpn_blocks.1
- [-1, 1, Conv, [256, 3, 2]] # 22, downsample_convs.0
- [[-1, 17], 1, Concat, [1]] # cat Y4
- [-1, 3, RepC3, [256]] # F4 (24), pan_blocks.0
- [-1, 1, Conv, [256, 3, 2]] # 25, downsample_convs.1
- [[-1, 12], 1, Concat, [1]] # cat Y5
- [-1, 3, RepC3, [256]] # F5 (27), pan_blocks.1
- [[21, 24, 27], 1, RTDETRDecoder, [nc]] # Detect(P3, P4, P5)
6.2 模型改进版本2⭐
此处以
ultralytics/cfg/models/rt-detr/rtdetr-l.yaml
为例,在同目录下创建一个用于自己数据集训练的模型文件
rtdetr-l-ResNetLayer_DynamicConv .yaml
。
将
rtdetr-l.yaml
中的内容复制到
rtdetr-l-ResNetLayer_DynamicConv .yaml
文件下,修改
nc
数量等于自己数据中目标的数量。
📌 模型的修改方法是将
网络
中的所有
ResNetLayer模块
替换成
ResNetLayer_DynamicConv 模块
。
# Ultralytics YOLO 🚀, AGPL-3.0 license
# RT-DETR-ResNet50 object detection model with P3-P5 outputs.
# Parameters
nc: 1 # number of classes
scales: # model compound scaling constants, i.e. 'model=yolov8n-cls.yaml' will call yolov8-cls.yaml with scale 'n'
# [depth, width, max_channels]
l: [1.00, 1.00, 1024]
backbone:
# [from, repeats, module, args]
- [-1, 1, ResNetLayer_DynamicConv, [3, 64, 1, True, 1]] # 0
- [-1, 1, ResNetLayer_DynamicConv, [64, 64, 1, False, 3]] # 1
- [-1, 1, ResNetLayer_DynamicConv, [256, 128, 2, False, 4]] # 2
- [-1, 1, ResNetLayer_DynamicConv, [512, 256, 2, False, 6]] # 3
- [-1, 1, ResNetLayer_DynamicConv, [1024, 512, 2, False, 3]] # 4
head:
- [-1, 1, Conv, [256, 1, 1, None, 1, 1, False]] # 5
- [-1, 1, AIFI, [1024, 8]]
- [-1, 1, Conv, [256, 1, 1]] # 7
- [-1, 1, nn.Upsample, [None, 2, "nearest"]]
- [3, 1, Conv, [256, 1, 1, None, 1, 1, False]] # 9
- [[-2, -1], 1, Concat, [1]]
- [-1, 3, RepC3, [256]] # 11
- [-1, 1, Conv, [256, 1, 1]] # 12
- [-1, 1, nn.Upsample, [None, 2, "nearest"]]
- [2, 1, Conv, [256, 1, 1, None, 1, 1, False]] # 14
- [[-2, -1], 1, Concat, [1]] # cat backbone P4
- [-1, 3, RepC3, [256]] # X3 (16), fpn_blocks.1
- [-1, 1, Conv, [256, 3, 2]] # 17, downsample_convs.0
- [[-1, 12], 1, Concat, [1]] # cat Y4
- [-1, 3, RepC3, [256]] # F4 (19), pan_blocks.0
- [-1, 1, Conv, [256, 3, 2]] # 20, downsample_convs.1
- [[-1, 7], 1, Concat, [1]] # cat Y5
- [-1, 3, RepC3, [256]] # F5 (22), pan_blocks.1
- [[16, 19, 22], 1, RTDETRDecoder, [nc]] # Detect(P3, P4, P5)
七、成功运行结果
打印网络模型可以看到
DynamicConv
和
ResNetLayer_DynamicConv
已经加入到模型中,并可以进行训练了。
rtdetr-l-DynamicConv :
rtdetr-l-DynamicConv summary: 570 layers, 45,781,387 parameters, 45,781,387 gradients, 88.9 GFLOPs
from n params module arguments
0 -1 1 25248 ultralytics.nn.modules.block.HGStem [3, 32, 48]
1 -1 6 155072 ultralytics.nn.modules.block.HGBlock [48, 48, 128, 3, 6]
2 -1 1 1408 ultralytics.nn.modules.conv.DWConv [128, 128, 3, 2, 1, False]
3 -1 6 839296 ultralytics.nn.modules.block.HGBlock [128, 96, 512, 3, 6]
4 -1 1 5632 ultralytics.nn.modules.conv.DWConv [512, 512, 3, 2, 1, False]
5 -1 6 6303768 ultralytics.nn.AddModules.DynamicConv.DynamicConv[512, 512]
6 -1 6 6303768 ultralytics.nn.AddModules.DynamicConv.DynamicConv[512, 512]
7 -1 6 6303768 ultralytics.nn.AddModules.DynamicConv.DynamicConv[512, 512]
8 -1 1 11264 ultralytics.nn.modules.conv.DWConv [512, 1024, 3, 2, 1, False]
9 -1 6 6708480 ultralytics.nn.modules.block.HGBlock [1024, 384, 2048, 5, 6, True, False]
10 -1 1 524800 ultralytics.nn.modules.conv.Conv [2048, 256, 1, 1, None, 1, 1, False]
11 -1 1 789760 ultralytics.nn.modules.transformer.AIFI [256, 1024, 8]
12 -1 1 66048 ultralytics.nn.modules.conv.Conv [256, 256, 1, 1]
13 -1 1 0 torch.nn.modules.upsampling.Upsample [None, 2, 'nearest']
14 7 1 131584 ultralytics.nn.modules.conv.Conv [512, 256, 1, 1, None, 1, 1, False]
15 [-2, -1] 1 0 ultralytics.nn.modules.conv.Concat [1]
16 -1 3 2232320 ultralytics.nn.modules.block.RepC3 [512, 256, 3]
17 -1 1 66048 ultralytics.nn.modules.conv.Conv [256, 256, 1, 1]
18 -1 1 0 torch.nn.modules.upsampling.Upsample [None, 2, 'nearest']
19 3 1 131584 ultralytics.nn.modules.conv.Conv [512, 256, 1, 1, None, 1, 1, False]
20 [-2, -1] 1 0 ultralytics.nn.modules.conv.Concat [1]
21 -1 3 2232320 ultralytics.nn.modules.block.RepC3 [512, 256, 3]
22 -1 1 590336 ultralytics.nn.modules.conv.Conv [256, 256, 3, 2]
23 [-1, 17] 1 0 ultralytics.nn.modules.conv.Concat [1]
24 -1 3 2232320 ultralytics.nn.modules.block.RepC3 [512, 256, 3]
25 -1 1 590336 ultralytics.nn.modules.conv.Conv [256, 256, 3, 2]
26 [-1, 12] 1 0 ultralytics.nn.modules.conv.Concat [1]
27 -1 3 2232320 ultralytics.nn.modules.block.RepC3 [512, 256, 3]
28 [21, 24, 27] 1 7303907 ultralytics.nn.modules.head.RTDETRDecoder [1, [256, 256, 256]]
rtdetr-l-DynamicConv summary: 570 layers, 45,781,387 parameters, 45,781,387 gradients, 88.9 GFLOPs
rtdetr-ResNetLayer_DynamicConv :
rtdetr-ResNetLayer_DynamicConv summary: 593 layers, 55,796,195 parameters, 55,796,195 gradients, 115.0 GFLOPs
from n params module arguments
0 -1 1 9536 ultralytics.nn.AddModules.DynamicConv.ResNetLayer_DynamicConv[3, 64, 1, True, 1]
1 -1 1 328332 ultralytics.nn.AddModules.DynamicConv.ResNetLayer_DynamicConv[64, 64, 1, False, 3]
2 -1 1 1913872 ultralytics.nn.AddModules.DynamicConv.ResNetLayer_DynamicConv[256, 128, 2, False, 4]
3 -1 1 11443224 ultralytics.nn.AddModules.DynamicConv.ResNetLayer_DynamicConv[512, 256, 2, False, 6]
4 -1 1 22846476 ultralytics.nn.AddModules.DynamicConv.ResNetLayer_DynamicConv[1024, 512, 2, False, 3]
5 -1 1 524800 ultralytics.nn.modules.conv.Conv [2048, 256, 1, 1, None, 1, 1, False]
6 -1 1 789760 ultralytics.nn.modules.transformer.AIFI [256, 1024, 8]
7 -1 1 66048 ultralytics.nn.modules.conv.Conv [256, 256, 1, 1]
8 -1 1 0 torch.nn.modules.upsampling.Upsample [None, 2, 'nearest']
9 3 1 262656 ultralytics.nn.modules.conv.Conv [1024, 256, 1, 1, None, 1, 1, False]
10 [-2, -1] 1 0 ultralytics.nn.modules.conv.Concat [1]
11 -1 3 2232320 ultralytics.nn.modules.block.RepC3 [512, 256, 3]
12 -1 1 66048 ultralytics.nn.modules.conv.Conv [256, 256, 1, 1]
13 -1 1 0 torch.nn.modules.upsampling.Upsample [None, 2, 'nearest']
14 2 1 131584 ultralytics.nn.modules.conv.Conv [512, 256, 1, 1, None, 1, 1, False]
15 [-2, -1] 1 0 ultralytics.nn.modules.conv.Concat [1]
16 -1 3 2232320 ultralytics.nn.modules.block.RepC3 [512, 256, 3]
17 -1 1 590336 ultralytics.nn.modules.conv.Conv [256, 256, 3, 2]
18 [-1, 12] 1 0 ultralytics.nn.modules.conv.Concat [1]
19 -1 3 2232320 ultralytics.nn.modules.block.RepC3 [512, 256, 3]
20 -1 1 590336 ultralytics.nn.modules.conv.Conv [256, 256, 3, 2]
21 [-1, 7] 1 0 ultralytics.nn.modules.conv.Concat [1]
22 -1 3 2232320 ultralytics.nn.modules.block.RepC3 [512, 256, 3]
23 [16, 19, 22] 1 7303907 ultralytics.nn.modules.head.RTDETRDecoder [1, [256, 256, 256]]
rtdetr-ResNetLayer_DynamicConv summary: 593 layers, 55,796,195 parameters, 55,796,195 gradients, 115.0 GFLOPs