YOLOv9独家改进|动态蛇形卷积Dynamic Snake Convolution与RepNCSPELAN4融合-编程知识

专栏介绍：YOLOv9改进系列 | 包含深度学习最新创新，主力高效涨点！！！

一、改进点介绍

Dynamic Snake Convolution是一种针对细长微弱的局部结构特征与复杂多变的全局形态特征设计的卷积模块。

RepNCSPELAN4是YOLOv9中的特征提取模块，类似YOLOv5和v8中的C2f与C3模块。

二、RepNCSPELAN4Dynamic模块详解

2.1 模块简介

RepNCSPELAN4Dynamic的主要思想：使用Dynamic Snake Convolution与RepNCSPELAN4中融合。

三、 RepNCSPELAN4Dynamic模块使用教程

3.1 RepNCSPELAN4Dynamic模块的代码

class RepNBottleneck_DySnakeConv(RepNBottleneck):# Standard bottleneckdef __init__(self, c1, c2, shortcut=True, g=1, k=(3, 3), e=0.5):  # ch_in, ch_out, shortcut, kernels, groups, expandsuper().__init__(c1, c2, shortcut, g, k, e)c_ = int(c2 * e)  # hidden channelsself.cv1 = RepConvN(c1, c_, k[0], 1)self.cv2 = Conv(c_, c2, k[1], s=1, g=g)self.add = shortcut and c1 == c2class RepNCSP_DySnakeConv(RepNCSP):# CSP Bottleneck with 3 convolutionsdef __init__(self, c1, c2, n=1, shortcut=True, g=1, e=0.5):  # ch_in, ch_out, number, shortcut, groups, expansionsuper().__init__(c1, c2, n, shortcut, g, e)c_ = int(c2 * e)  # hidden channelsself.cv1 = DySnakeConv(c1, c_)self.cv2 = DySnakeConv(c1, c_)self.cv3 = DySnakeConv(2 * c_, c2)  # optional act=FReLU(c2)self.m = nn.Sequential(*(RepNBottleneck_DySnakeConv(c_, c_, shortcut, g, e=1.0) for _ in range(n)))class RepNCSPELAN4DySnakeConv(RepNCSPELAN4):# csp-elandef __init__(self, c1, c2, c3, c4, c5=1):  # ch_in, ch_out, number, shortcut, groups, expansionsuper().__init__(c1, c2, c3, c4, c5)self.cv1 = Conv(c1, c3, k=1, s=1)self.cv2 = nn.Sequential(RepNCSP_DySnakeConv(c3 // 2, c4, c5), DySnakeConv(c4, c4, 3))self.cv3 = nn.Sequential(RepNCSP_DySnakeConv(c4, c4, c5), DySnakeConv(c4, c4, 3))self.cv4 = Conv(c3 + (2 * c4), c2, 1, 1)class DySnakeConv(nn.Module):def __init__(self, inc, ouc, k=3) -> None:super().__init__()self.conv_0 = Conv(inc, ouc, k)self.conv_x = DSConv(inc, ouc, 0, k)self.conv_y = DSConv(inc, ouc, 1, k)def forward(self, x):return torch.cat([self.conv_0(x), self.conv_x(x), self.conv_y(x)], dim=1)class DSConv(nn.Module):def __init__(self, in_ch, out_ch, morph, kernel_size=3, if_offset=True, extend_scope=1):"""The Dynamic Snake Convolution:param in_ch: input channel:param out_ch: output channel:param kernel_size: the size of kernel:param extend_scope: the range to expand (default 1 for this method):param morph: the morphology of the convolution kernel is mainly divided into two typesalong the x-axis (0) and the y-axis (1) (see the paper for details):param if_offset: whether deformation is required, if it is False, it is the standard convolution kernel"""super(DSConv, self).__init__()# use the <offset_conv> to learn the deformable offsetself.offset_conv = nn.Conv2d(in_ch, 2 * kernel_size, 3, padding=1)self.bn = nn.BatchNorm2d(2 * kernel_size)self.kernel_size = kernel_size# two types of the DSConv (along x-axis and y-axis)self.dsc_conv_x = nn.Conv2d(in_ch,out_ch,kernel_size=(kernel_size, 1),stride=(kernel_size, 1),padding=0,)self.dsc_conv_y = nn.Conv2d(in_ch,out_ch,kernel_size=(1, kernel_size),stride=(1, kernel_size),padding=0,)self.gn = nn.GroupNorm(out_ch // 4, out_ch)self.act = Conv.default_actself.extend_scope = extend_scopeself.morph = morphself.if_offset = if_offsetdef forward(self, f):offset = self.offset_conv(f)offset = self.bn(offset)# We need a range of deformation between -1 and 1 to mimic the snake's swingoffset = torch.tanh(offset)input_shape = f.shapedsc = DSC(input_shape, self.kernel_size, self.extend_scope, self.morph)deformed_feature = dsc.deform_conv(f, offset, self.if_offset)if self.morph == 0:x = self.dsc_conv_x(deformed_feature.type(f.dtype))x = self.gn(x)x = self.act(x)return xelse:x = self.dsc_conv_y(deformed_feature.type(f.dtype))x = self.gn(x)x = self.act(x)return x# Core code, for ease of understanding, we mark the dimensions of input and output next to the code
class DSC(object):def __init__(self, input_shape, kernel_size, extend_scope, morph):self.num_points = kernel_sizeself.width = input_shape[2]self.height = input_shape[3]self.morph = morphself.extend_scope = extend_scope  # offset (-1 ~ 1) * extend_scope# define feature map shape"""B: Batch size  C: Channel  W: Width  H: Height"""self.num_batch = input_shape[0]self.num_channels = input_shape[1]"""input: offset [B,2*K,W,H]  K: Kernel size (2*K: 2D image, deformation contains <x_offset> and <y_offset>)output_x: [B,1,W,K*H]   coordinate mapoutput_y: [B,1,K*W,H]   coordinate map"""def _coordinate_map_3D(self, offset, if_offset):device = offset.device# offsety_offset, x_offset = torch.split(offset, self.num_points, dim=1)y_center = torch.arange(0, self.width).repeat([self.height])y_center = y_center.reshape(self.height, self.width)y_center = y_center.permute(1, 0)y_center = y_center.reshape([-1, self.width, self.height])y_center = y_center.repeat([self.num_points, 1, 1]).float()y_center = y_center.unsqueeze(0)x_center = torch.arange(0, self.height).repeat([self.width])x_center = x_center.reshape(self.width, self.height)x_center = x_center.permute(0, 1)x_center = x_center.reshape([-1, self.width, self.height])x_center = x_center.repeat([self.num_points, 1, 1]).float()x_center = x_center.unsqueeze(0)if self.morph == 0:"""Initialize the kernel and flatten the kernely: only need 0x: -num_points//2 ~ num_points//2 (Determined by the kernel size)!!! The related PPT will be submitted later, and the PPT will contain the whole changes of each step"""y = torch.linspace(0, 0, 1)x = torch.linspace(-int(self.num_points // 2),int(self.num_points // 2),int(self.num_points),)y, x = torch.meshgrid(y, x)y_spread = y.reshape(-1, 1)x_spread = x.reshape(-1, 1)y_grid = y_spread.repeat([1, self.width * self.height])y_grid = y_grid.reshape([self.num_points, self.width, self.height])y_grid = y_grid.unsqueeze(0)  # [B*K*K, W,H]x_grid = x_spread.repeat([1, self.width * self.height])x_grid = x_grid.reshape([self.num_points, self.width, self.height])x_grid = x_grid.unsqueeze(0)  # [B*K*K, W,H]y_new = y_center + y_gridx_new = x_center + x_gridy_new = y_new.repeat(self.num_batch, 1, 1, 1).to(device)x_new = x_new.repeat(self.num_batch, 1, 1, 1).to(device)y_offset_new = y_offset.detach().clone()if if_offset:y_offset = y_offset.permute(1, 0, 2, 3)y_offset_new = y_offset_new.permute(1, 0, 2, 3)center = int(self.num_points // 2)# The center position remains unchanged and the rest of the positions begin to swing# This part is quite simple. The main idea is that "offset is an iterative process"y_offset_new[center] = 0for index in range(1, center):y_offset_new[center + index] = (y_offset_new[center + index - 1] + y_offset[center + index])y_offset_new[center - index] = (y_offset_new[center - index + 1] + y_offset[center - index])y_offset_new = y_offset_new.permute(1, 0, 2, 3).to(device)y_new = y_new.add(y_offset_new.mul(self.extend_scope))y_new = y_new.reshape([self.num_batch, self.num_points, 1, self.width, self.height])y_new = y_new.permute(0, 3, 1, 4, 2)y_new = y_new.reshape([self.num_batch, self.num_points * self.width, 1 * self.height])x_new = x_new.reshape([self.num_batch, self.num_points, 1, self.width, self.height])x_new = x_new.permute(0, 3, 1, 4, 2)x_new = x_new.reshape([self.num_batch, self.num_points * self.width, 1 * self.height])return y_new, x_newelse:"""Initialize the kernel and flatten the kernely: -num_points//2 ~ num_points//2 (Determined by the kernel size)x: only need 0"""y = torch.linspace(-int(self.num_points // 2),int(self.num_points // 2),int(self.num_points),)x = torch.linspace(0, 0, 1)y, x = torch.meshgrid(y, x)y_spread = y.reshape(-1, 1)x_spread = x.reshape(-1, 1)y_grid = y_spread.repeat([1, self.width * self.height])y_grid = y_grid.reshape([self.num_points, self.width, self.height])y_grid = y_grid.unsqueeze(0)x_grid = x_spread.repeat([1, self.width * self.height])x_grid = x_grid.reshape([self.num_points, self.width, self.height])x_grid = x_grid.unsqueeze(0)y_new = y_center + y_gridx_new = x_center + x_gridy_new = y_new.repeat(self.num_batch, 1, 1, 1)x_new = x_new.repeat(self.num_batch, 1, 1, 1)y_new = y_new.to(device)x_new = x_new.to(device)x_offset_new = x_offset.detach().clone()if if_offset:x_offset = x_offset.permute(1, 0, 2, 3)x_offset_new = x_offset_new.permute(1, 0, 2, 3)center = int(self.num_points // 2)x_offset_new[center] = 0for index in range(1, center):x_offset_new[center + index] = (x_offset_new[center + index - 1] + x_offset[center + index])x_offset_new[center - index] = (x_offset_new[center - index + 1] + x_offset[center - index])x_offset_new = x_offset_new.permute(1, 0, 2, 3).to(device)x_new = x_new.add(x_offset_new.mul(self.extend_scope))y_new = y_new.reshape([self.num_batch, 1, self.num_points, self.width, self.height])y_new = y_new.permute(0, 3, 1, 4, 2)y_new = y_new.reshape([self.num_batch, 1 * self.width, self.num_points * self.height])x_new = x_new.reshape([self.num_batch, 1, self.num_points, self.width, self.height])x_new = x_new.permute(0, 3, 1, 4, 2)x_new = x_new.reshape([self.num_batch, 1 * self.width, self.num_points * self.height])return y_new, x_new"""input: input feature map [N,C,D,W,H]；coordinate map [N,K*D,K*W,K*H] output: [N,1,K*D,K*W,K*H]  deformed feature map"""def _bilinear_interpolate_3D(self, input_feature, y, x):device = input_feature.devicey = y.reshape([-1]).float()x = x.reshape([-1]).float()zero = torch.zeros([]).int()max_y = self.width - 1max_x = self.height - 1# find 8 grid locationsy0 = torch.floor(y).int()y1 = y0 + 1x0 = torch.floor(x).int()x1 = x0 + 1# clip out coordinates exceeding feature map volumey0 = torch.clamp(y0, zero, max_y)y1 = torch.clamp(y1, zero, max_y)x0 = torch.clamp(x0, zero, max_x)x1 = torch.clamp(x1, zero, max_x)input_feature_flat = input_feature.flatten()input_feature_flat = input_feature_flat.reshape(self.num_batch, self.num_channels, self.width, self.height)input_feature_flat = input_feature_flat.permute(0, 2, 3, 1)input_feature_flat = input_feature_flat.reshape(-1, self.num_channels)dimension = self.height * self.widthbase = torch.arange(self.num_batch) * dimensionbase = base.reshape([-1, 1]).float()repeat = torch.ones([self.num_points * self.width * self.height]).unsqueeze(0)repeat = repeat.float()base = torch.matmul(base, repeat)base = base.reshape([-1])base = base.to(device)base_y0 = base + y0 * self.heightbase_y1 = base + y1 * self.height# top rectangle of the neighbourhood volumeindex_a0 = base_y0 - base + x0index_c0 = base_y0 - base + x1# bottom rectangle of the neighbourhood volumeindex_a1 = base_y1 - base + x0index_c1 = base_y1 - base + x1# get 8 grid valuesvalue_a0 = input_feature_flat[index_a0.type(torch.int64)].to(device)value_c0 = input_feature_flat[index_c0.type(torch.int64)].to(device)value_a1 = input_feature_flat[index_a1.type(torch.int64)].to(device)value_c1 = input_feature_flat[index_c1.type(torch.int64)].to(device)# find 8 grid locationsy0 = torch.floor(y).int()y1 = y0 + 1x0 = torch.floor(x).int()x1 = x0 + 1# clip out coordinates exceeding feature map volumey0 = torch.clamp(y0, zero, max_y + 1)y1 = torch.clamp(y1, zero, max_y + 1)x0 = torch.clamp(x0, zero, max_x + 1)x1 = torch.clamp(x1, zero, max_x + 1)x0_float = x0.float()x1_float = x1.float()y0_float = y0.float()y1_float = y1.float()vol_a0 = ((y1_float - y) * (x1_float - x)).unsqueeze(-1).to(device)vol_c0 = ((y1_float - y) * (x - x0_float)).unsqueeze(-1).to(device)vol_a1 = ((y - y0_float) * (x1_float - x)).unsqueeze(-1).to(device)vol_c1 = ((y - y0_float) * (x - x0_float)).unsqueeze(-1).to(device)outputs = (value_a0 * vol_a0 + value_c0 * vol_c0 + value_a1 * vol_a1 +value_c1 * vol_c1)if self.morph == 0:outputs = outputs.reshape([self.num_batch,self.num_points * self.width,1 * self.height,self.num_channels,])outputs = outputs.permute(0, 3, 1, 2)else:outputs = outputs.reshape([self.num_batch,1 * self.width,self.num_points * self.height,self.num_channels,])outputs = outputs.permute(0, 3, 1, 2)return outputsdef deform_conv(self, input, offset, if_offset):y, x = self._coordinate_map_3D(offset, if_offset)deformed_feature = self._bilinear_interpolate_3D(input, y, x)return deformed_feature

3.2 在YOlO v9中的添加教程

阅读YOLOv9添加模块教程或使用下文操作

1. 将YOLOv9工程中models下common.py文件中的最下行（否则可能因类继承报错）增加模块的代码。

2. 将YOLOv9工程中models下yolo.py文件中的第681行（可能因版本变化而变化）增加以下代码。

            RepNCSPELAN4, SPPELAN, RepNCSPELAN4DySnakeConv}:

3.3 运行配置文件

# YOLOv9
# Powered bu https://blog.csdn.net/StopAndGoyyy# parameters
nc: 80  # number of classes
#depth_multiple: 0.33  # model depth multiple
depth_multiple: 1  # model depth multiple
#width_multiple: 0.25  # layer channel multiple
width_multiple: 1  # layer channel multiple
#activation: nn.LeakyReLU(0.1)
#activation: nn.ReLU()# anchors
anchors: 3# YOLOv9 backbone
backbone:[[-1, 1, Silence, []],  # conv down[-1, 1, Conv, [64, 3, 2]],  # 1-P1/2# conv down[-1, 1, Conv, [128, 3, 2]],  # 2-P2/4# elan-1 block[-1, 1, RepNCSPELAN4DySnakeConv, [256, 128, 64, 1]],  # 3# avg-conv down[-1, 1, ADown, [256]],  # 4-P3/8# elan-2 block[-1, 1, RepNCSPELAN4, [512, 256, 128, 1]],  # 5# avg-conv down[-1, 1, ADown, [512]],  # 6-P4/16# elan-2 block[-1, 1, RepNCSPELAN4, [512, 512, 256, 1]],  # 7# avg-conv down[-1, 1, ADown, [512]],  # 8-P5/32# elan-2 block[-1, 1, RepNCSPELAN4, [512, 512, 256, 1]],  # 9]# YOLOv9 head
head:[# elan-spp block[-1, 1, SPPELAN, [512, 256]],  # 10# up-concat merge[-1, 1, nn.Upsample, [None, 2, 'nearest']],[[-1, 7], 1, Concat, [1]],  # cat backbone P4# elan-2 block[-1, 1, RepNCSPELAN4, [512, 512, 256, 1]],  # 13# up-concat merge[-1, 1, nn.Upsample, [None, 2, 'nearest']],[[-1, 5], 1, Concat, [1]],  # cat backbone P3# elan-2 block[-1, 1, RepNCSPELAN4, [256, 256, 128, 1]],  # 16 (P3/8-small)# avg-conv-down merge[-1, 1, ADown, [256]],[[-1, 13], 1, Concat, [1]],  # cat head P4# elan-2 block[-1, 1, RepNCSPELAN4, [512, 512, 256, 1]],  # 19 (P4/16-medium)# avg-conv-down merge[-1, 1, ADown, [512]],[[-1, 10], 1, Concat, [1]],  # cat head P5# elan-2 block[-1, 1, RepNCSPELAN4, [512, 512, 256, 1]],  # 22 (P5/32-large)# multi-level reversible auxiliary branch# routing[5, 1, CBLinear, [[256]]], # 23[7, 1, CBLinear, [[256, 512]]], # 24[9, 1, CBLinear, [[256, 512, 512]]], # 25# conv down[0, 1, Conv, [64, 3, 2]],  # 26-P1/2# conv down[-1, 1, Conv, [128, 3, 2]],  # 27-P2/4# elan-1 block[-1, 1, RepNCSPELAN4, [256, 128, 64, 1]],  # 28# avg-conv down fuse[-1, 1, ADown, [256]],  # 29-P3/8[[23, 24, 25, -1], 1, CBFuse, [[0, 0, 0]]], # 30  # elan-2 block[-1, 1, RepNCSPELAN4, [512, 256, 128, 1]],  # 31# avg-conv down fuse[-1, 1, ADown, [512]],  # 32-P4/16[[24, 25, -1], 1, CBFuse, [[1, 1]]], # 33 # elan-2 block[-1, 1, RepNCSPELAN4, [512, 512, 256, 1]],  # 34# avg-conv down fuse[-1, 1, ADown, [512]],  # 35-P5/32[[25, -1], 1, CBFuse, [[2]]], # 36# elan-2 block[-1, 1, RepNCSPELAN4, [512, 512, 256, 1]],  # 37# detection head# detect[[31, 34, 37, 16, 19, 22], 1, DualDDetect, [nc]],  # DualDDetect(A3, A4, A5, P3, P4, P5)]