学习资源站

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_动态卷积块cvpr2024-

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 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:

在这里插入图片描述

4.2 改进点2⭐

模块改进方法 :基于 DynamicConv模块 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)

在这里插入图片描述

注意❗:在 第五小节 中需要声明的模块名称为: DynamicConv 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

在这里插入图片描述

5.2 修改二

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 *

在这里插入图片描述

5.3 修改三

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

在这里插入图片描述

其次:在 parse_model函数 中注册 DynamicConv ResNetLayer_DynamicConv 模块

在这里插入图片描述
在这里插入图片描述
在这里插入图片描述


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

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

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 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