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YOLO11改进-注意力-引入双层路由注意力机制(Biformer)

          本篇文章将介绍一个新的改进模块——Biformer,并阐述如何将其应用于YOLOv11中,显著提升模型性能。首先,我们将解析Biformer他做了什么,BiFormer 是一种新型视觉Transformer架构,通过双层路由注意力机制(Bi-level Routing Attention, BRA)实现动态、查询感知的稀疏注意力,从而在保持高计算效率的同时,捕捉长距离依赖关系随后,我们会详细说明如何将该模块与YOLOv11相结合,展示代码实现细节及其使用方法,最终展现这一改进对目标检测效果的积极影响。

1. 双层路由注意力机制Biformer结构介绍      

        BiFormer 旨在通过双层路由注意力机制(Bi-level Routing Attention, BRA)实现动态、查询感知的稀疏注意力。

  1. 双层路由注意力机制

    • 区域级路由:首先在粗粒度的区域级别过滤掉大部分不相关的键值对,仅保留少量相关区域。
    • 细粒度注意力:在保留的区域内进行细粒度的token-to-token注意力计算。
  2. Biformer的实现步骤

    • 区域划分和输入投影:将输入特征图划分为多个不重叠的区域,并通过线性投影生成查询、键和值张量。
    • 区域间路由:构建区域级别的邻接图,并通过矩阵乘法计算区域间的亲和度,保留每个区域最相关的k个连接。
    • token-to-token注意力:在保留的区域内进行token-to-token注意力计算,并通过硬件友好的密集矩阵乘法实现。

2. YOLOv11与Biformer的结合   

        本文将YOLOv11模型的C2PSA模块中的注意力层替换Biformer,组合成C2PSA_biformer模块,通过Biformer实现动态、查询感知的稀疏注意力,捕捉长距离依赖关系,从而提高了C2PSA_biformer模块对长距离特征捕捉。

3. Biformer代码部分

from typing import Tuple, Optional

import torch
import torch.nn as nn
import torch.nn.functional as F
from einops import rearrange
from torch import Tensor, LongTensor
from .block import PSABlock,C2PSA


class TopkRouting(nn.Module):
    """
    differentiable topk routing with scaling
    Args:
        qk_dim: int, feature dimension of query and key
        topk: int, the 'topk'
        qk_scale: int or None, temperature (multiply) of softmax activation
        with_param: bool, wether inorporate learnable params in routing unit
        diff_routing: bool, wether make routing differentiable
        soft_routing: bool, wether make output value multiplied by routing weights
    """

    def __init__(self, qk_dim, topk=4, qk_scale=None, param_routing=False, diff_routing=False):
        super().__init__()
        self.topk = topk
        self.qk_dim = qk_dim
        self.scale = qk_scale or qk_dim ** -0.5
        self.diff_routing = diff_routing
        # TODO: norm layer before/after linear?
        self.emb = nn.Linear(qk_dim, qk_dim) if param_routing else nn.Identity()
        # routing activation
        self.routing_act = nn.Softmax(dim=-1)

    def forward(self, query: Tensor, key: Tensor) -> Tuple[Tensor]:
        """
        Args:
            q, k: (n, p^2, c) tensor
        Return:
            r_weight, topk_index: (n, p^2, topk) tensor
        """
        if not self.diff_routing:
            query, key = query.detach(), key.detach()
        query_hat, key_hat = self.emb(query), self.emb(key)  # per-window pooling -> (n, p^2, c)
        attn_logit = (query_hat * self.scale) @ key_hat.transpose(-2, -1)  # (n, p^2, p^2)
        topk_attn_logit, topk_index = torch.topk(attn_logit, k=self.topk, dim=-1)  # (n, p^2, k), (n, p^2, k)
        r_weight = self.routing_act(topk_attn_logit)  # (n, p^2, k)

        return r_weight, topk_index


class KVGather(nn.Module):
    def __init__(self, mul_weight='none'):
        super().__init__()
        assert mul_weight in ['none', 'soft', 'hard']
        self.mul_weight = mul_weight

    def forward(self, r_idx: Tensor, r_weight: Tensor, kv: Tensor):
        """
        r_idx: (n, p^2, topk) tensor
        r_weight: (n, p^2, topk) tensor
        kv: (n, p^2, w^2, c_kq+c_v)

        Return:
            (n, p^2, topk, w^2, c_kq+c_v) tensor
        """
        # select kv according to routing index
        n, p2, w2, c_kv = kv.size()
        topk = r_idx.size(-1)
        # print(r_idx.size(), r_weight.size())
        # FIXME: gather consumes much memory (topk times redundancy), write cuda kernel?
        topk_kv = torch.gather(kv.view(n, 1, p2, w2, c_kv).expand(-1, p2, -1, -1, -1),
                               # (n, p^2, p^2, w^2, c_kv) without mem cpy
                               dim=2,
                               index=r_idx.view(n, p2, topk, 1, 1).expand(-1, -1, -1, w2, c_kv)
                               # (n, p^2, k, w^2, c_kv)
                               )

        if self.mul_weight == 'soft':
            topk_kv = r_weight.view(n, p2, topk, 1, 1) * topk_kv  # (n, p^2, k, w^2, c_kv)
        elif self.mul_weight == 'hard':
            raise NotImplementedError('differentiable hard routing TBA')
        # else: #'none'
        #     topk_kv = topk_kv # do nothing

        return topk_kv


class QKVLinear(nn.Module):
    def __init__(self, dim, qk_dim, bias=True):
        super().__init__()
        self.dim = dim
        self.qk_dim = qk_dim
        self.qkv = nn.Linear(dim, qk_dim + qk_dim + dim, bias=bias)

    def forward(self, x):
        q, kv = self.qkv(x).split([self.qk_dim, self.qk_dim + self.dim], dim=-1)
        return q, kv
        # q, k, v = self.qkv(x).split([self.qk_dim, self.qk_dim, self.dim], dim=-1)
        # return q, k, v


class BiLevelRoutingAttention(nn.Module):
    """
    n_win: number of windows in one side (so the actual number of windows is n_win*n_win)
    kv_per_win: for kv_downsample_mode='ada_xxxpool' only, number of key/values per window. Similar to n_win, the actual number is kv_per_win*kv_per_win.
    topk: topk for window filtering
    param_attention: 'qkvo'-linear for q,k,v and o, 'none': param free attention
    param_routing: extra linear for routing
    diff_routing: wether to set routing differentiable
    soft_routing: wether to multiply soft routing weights
    """

    def __init__(self, dim, n_win=7, num_heads=8, qk_dim=None, qk_scale=None,
                 kv_per_win=4, kv_downsample_ratio=4, kv_downsample_kernel=None, kv_downsample_mode='identity',
                 topk=4, param_attention="qkvo", param_routing=False, diff_routing=False, soft_routing=False,
                 side_dwconv=3,
                 auto_pad=True):
        super().__init__()
        # local attention setting
        self.dim = dim
        self.n_win = n_win  # Wh, Ww
        self.num_heads = num_heads
        self.qk_dim = qk_dim or dim
        assert self.qk_dim % num_heads == 0 and self.dim % num_heads == 0, 'qk_dim and dim must be divisible by num_heads!'
        self.scale = qk_scale or self.qk_dim ** -0.5

        ################side_dwconv (i.e. LCE in ShuntedTransformer)###########
        self.lepe = nn.Conv2d(dim, dim, kernel_size=side_dwconv, stride=1, padding=side_dwconv // 2,
                              groups=dim) if side_dwconv > 0 else \
            lambda x: torch.zeros_like(x)

        ################ global routing setting #################
        self.topk = topk
        self.param_routing = param_routing
        self.diff_routing = diff_routing
        self.soft_routing = soft_routing
        # router
        assert not (self.param_routing and not self.diff_routing)  # cannot be with_param=True and diff_routing=False
        self.router = TopkRouting(qk_dim=self.qk_dim,
                                  qk_scale=self.scale,
                                  topk=self.topk,
                                  diff_routing=self.diff_routing,
                                  param_routing=self.param_routing)
        if self.soft_routing:  # soft routing, always diffrentiable (if no detach)
            mul_weight = 'soft'
        elif self.diff_routing:  # hard differentiable routing
            mul_weight = 'hard'
        else:  # hard non-differentiable routing
            mul_weight = 'none'
        self.kv_gather = KVGather(mul_weight=mul_weight)

        # qkv mapping (shared by both global routing and local attention)
        self.param_attention = param_attention
        if self.param_attention == 'qkvo':
            self.qkv = QKVLinear(self.dim, self.qk_dim)
            self.wo = nn.Linear(dim, dim)
        elif self.param_attention == 'qkv':
            self.qkv = QKVLinear(self.dim, self.qk_dim)
            self.wo = nn.Identity()
        else:
            raise ValueError(f'param_attention mode {self.param_attention} is not surpported!')

        self.kv_downsample_mode = kv_downsample_mode
        self.kv_per_win = kv_per_win
        self.kv_downsample_ratio = kv_downsample_ratio
        self.kv_downsample_kenel = kv_downsample_kernel
        if self.kv_downsample_mode == 'ada_avgpool':
            assert self.kv_per_win is not None
            self.kv_down = nn.AdaptiveAvgPool2d(self.kv_per_win)
        elif self.kv_downsample_mode == 'ada_maxpool':
            assert self.kv_per_win is not None
            self.kv_down = nn.AdaptiveMaxPool2d(self.kv_per_win)
        elif self.kv_downsample_mode == 'maxpool':
            assert self.kv_downsample_ratio is not None
            self.kv_down = nn.MaxPool2d(self.kv_downsample_ratio) if self.kv_downsample_ratio > 1 else nn.Identity()
        elif self.kv_downsample_mode == 'avgpool':
            assert self.kv_downsample_ratio is not None
            self.kv_down = nn.AvgPool2d(self.kv_downsample_ratio) if self.kv_downsample_ratio > 1 else nn.Identity()
        elif self.kv_downsample_mode == 'identity':  # no kv downsampling
            self.kv_down = nn.Identity()
        elif self.kv_downsample_mode == 'fracpool':
            # assert self.kv_downsample_ratio is not None
            # assert self.kv_downsample_kenel is not None
            # TODO: fracpool
            # 1. kernel size should be input size dependent
            # 2. there is a random factor, need to avoid independent sampling for k and v
            raise NotImplementedError('fracpool policy is not implemented yet!')
        elif kv_downsample_mode == 'conv':
            # TODO: need to consider the case where k != v so that need two downsample modules
            raise NotImplementedError('conv policy is not implemented yet!')
        else:
            raise ValueError(f'kv_down_sample_mode {self.kv_downsaple_mode} is not surpported!')

        # softmax for local attention
        self.attn_act = nn.Softmax(dim=-1)

        self.auto_pad = auto_pad

    def forward(self, x, ret_attn_mask=False):
        """
        x: NHWC tensor

        Return:
            NHWC tensor
        """
        x = rearrange(x, "n c h w -> n h w c")
        # NOTE: use padding for semantic segmentation
        ###################################################
        if self.auto_pad:
            N, H_in, W_in, C = x.size()

            pad_l = pad_t = 0
            pad_r = (self.n_win - W_in % self.n_win) % self.n_win
            pad_b = (self.n_win - H_in % self.n_win) % self.n_win
            x = F.pad(x, (0, 0,  # dim=-1
                          pad_l, pad_r,  # dim=-2
                          pad_t, pad_b))  # dim=-3
            _, H, W, _ = x.size()  # padded size
        else:
            N, H, W, C = x.size()
            assert H % self.n_win == 0 and W % self.n_win == 0  #
        ###################################################

        # patchify, (n, p^2, w, w, c), keep 2d window as we need 2d pooling to reduce kv size
        x = rearrange(x, "n (j h) (i w) c -> n (j i) h w c", j=self.n_win, i=self.n_win)

        #################qkv projection###################
        # q: (n, p^2, w, w, c_qk)
        # kv: (n, p^2, w, w, c_qk+c_v)
        # NOTE: separte kv if there were memory leak issue caused by gather
        q, kv = self.qkv(x)

        # pixel-wise qkv
        # q_pix: (n, p^2, w^2, c_qk)
        # kv_pix: (n, p^2, h_kv*w_kv, c_qk+c_v)
        q_pix = rearrange(q, 'n p2 h w c -> n p2 (h w) c')
        kv_pix = self.kv_down(rearrange(kv, 'n p2 h w c -> (n p2) c h w'))
        kv_pix = rearrange(kv_pix, '(n j i) c h w -> n (j i) (h w) c', j=self.n_win, i=self.n_win)

        q_win, k_win = q.mean([2, 3]), kv[..., 0:self.qk_dim].mean(
            [2, 3])  # window-wise qk, (n, p^2, c_qk), (n, p^2, c_qk)

        ##################side_dwconv(lepe)##################
        # NOTE: call contiguous to avoid gradient warning when using ddp
        lepe = self.lepe(rearrange(kv[..., self.qk_dim:], 'n (j i) h w c -> n c (j h) (i w)', j=self.n_win,
                                   i=self.n_win).contiguous())
        lepe = rearrange(lepe, 'n c (j h) (i w) -> n (j h) (i w) c', j=self.n_win, i=self.n_win)

        ############ gather q dependent k/v #################

        r_weight, r_idx = self.router(q_win, k_win)  # both are (n, p^2, topk) tensors

        kv_pix_sel = self.kv_gather(r_idx=r_idx, r_weight=r_weight, kv=kv_pix)  # (n, p^2, topk, h_kv*w_kv, c_qk+c_v)
        k_pix_sel, v_pix_sel = kv_pix_sel.split([self.qk_dim, self.dim], dim=-1)
        # kv_pix_sel: (n, p^2, topk, h_kv*w_kv, c_qk)
        # v_pix_sel: (n, p^2, topk, h_kv*w_kv, c_v)

        ######### do attention as normal ####################
        k_pix_sel = rearrange(k_pix_sel, 'n p2 k w2 (m c) -> (n p2) m c (k w2)',
                              m=self.num_heads)  # flatten to BMLC, (n*p^2, m, topk*h_kv*w_kv, c_kq//m) transpose here?
        v_pix_sel = rearrange(v_pix_sel, 'n p2 k w2 (m c) -> (n p2) m (k w2) c',
                              m=self.num_heads)  # flatten to BMLC, (n*p^2, m, topk*h_kv*w_kv, c_v//m)
        q_pix = rearrange(q_pix, 'n p2 w2 (m c) -> (n p2) m w2 c',
                          m=self.num_heads)  # to BMLC tensor (n*p^2, m, w^2, c_qk//m)

        # param-free multihead attention
        attn_weight = (
                                  q_pix * self.scale) @ k_pix_sel  # (n*p^2, m, w^2, c) @ (n*p^2, m, c, topk*h_kv*w_kv) -> (n*p^2, m, w^2, topk*h_kv*w_kv)
        attn_weight = self.attn_act(attn_weight)
        out = attn_weight @ v_pix_sel  # (n*p^2, m, w^2, topk*h_kv*w_kv) @ (n*p^2, m, topk*h_kv*w_kv, c) -> (n*p^2, m, w^2, c)
        out = rearrange(out, '(n j i) m (h w) c -> n (j h) (i w) (m c)', j=self.n_win, i=self.n_win,
                        h=H // self.n_win, w=W // self.n_win)

        out = out + lepe
        # output linear
        out = self.wo(out)

        # NOTE: use padding for semantic segmentation
        # crop padded region
        if self.auto_pad and (pad_r > 0 or pad_b > 0):
            out = out[:, :H_in, :W_in, :].contiguous()

        if ret_attn_mask:
            return out, r_weight, r_idx, attn_weight
        else:
            return rearrange(out, "n h w c -> n c h w")


class Attention(nn.Module):
    """
    vanilla attention
    """

    def __init__(self, dim, num_heads=8, qkv_bias=False, qk_scale=None, attn_drop=0., proj_drop=0.):
        super().__init__()
        self.num_heads = num_heads
        head_dim = dim // num_heads
        # NOTE scale factor was wrong in my original version, can set manually to be compat with prev weights
        self.scale = qk_scale or head_dim ** -0.5

        self.qkv = nn.Linear(dim, dim * 3, bias=qkv_bias)
        self.attn_drop = nn.Dropout(attn_drop)
        self.proj = nn.Linear(dim, dim)
        self.proj_drop = nn.Dropout(proj_drop)

    def forward(self, x):
        """
        args:
            x: NCHW tensor
        return:
            NCHW tensor
        """
        _, _, H, W = x.size()
        x = rearrange(x, 'n c h w -> n (h w) c')

        #######################################
        B, N, C = x.shape
        qkv = self.qkv(x).reshape(B, N, 3, self.num_heads, C // self.num_heads).permute(2, 0, 3, 1, 4)
        q, k, v = qkv[0], qkv[1], qkv[2]  # make torchscript happy (cannot use tensor as tuple)

        attn = (q @ k.transpose(-2, -1)) * self.scale
        attn = attn.softmax(dim=-1)
        attn = self.attn_drop(attn)

        x = (attn @ v).transpose(1, 2).reshape(B, N, C)
        x = self.proj(x)
        x = self.proj_drop(x)
        #######################################

        x = rearrange(x, 'n (h w) c -> n c h w', h=H, w=W)
        return x


class AttentionLePE(nn.Module):
    """
    vanilla attention
    """

    def __init__(self, dim, num_heads=8, qkv_bias=False, qk_scale=None, attn_drop=0., proj_drop=0., side_dwconv=5):
        super().__init__()
        self.num_heads = num_heads
        head_dim = dim // num_heads
        # NOTE scale factor was wrong in my original version, can set manually to be compat with prev weights
        self.scale = qk_scale or head_dim ** -0.5

        self.qkv = nn.Linear(dim, dim * 3, bias=qkv_bias)
        self.attn_drop = nn.Dropout(attn_drop)
        self.proj = nn.Linear(dim, dim)
        self.proj_drop = nn.Dropout(proj_drop)
        self.lepe = nn.Conv2d(dim, dim, kernel_size=side_dwconv, stride=1, padding=side_dwconv // 2,
                              groups=dim) if side_dwconv > 0 else \
            lambda x: torch.zeros_like(x)

    def forward(self, x):
        """
        args:
            x: NCHW tensor
        return:
            NCHW tensor
        """
        _, _, H, W = x.size()
        x = rearrange(x, 'n c h w -> n (h w) c')

        #######################################
        B, N, C = x.shape
        qkv = self.qkv(x).reshape(B, N, 3, self.num_heads, C // self.num_heads).permute(2, 0, 3, 1, 4)
        q, k, v = qkv[0], qkv[1], qkv[2]  # make torchscript happy (cannot use tensor as tuple)

        lepe = self.lepe(rearrange(x, 'n (h w) c -> n c h w', h=H, w=W))
        lepe = rearrange(lepe, 'n c h w -> n (h w) c')

        attn = (q @ k.transpose(-2, -1)) * self.scale
        attn = attn.softmax(dim=-1)
        attn = self.attn_drop(attn)

        x = (attn @ v).transpose(1, 2).reshape(B, N, C)
        x = x + lepe

        x = self.proj(x)
        x = self.proj_drop(x)
        #######################################

        x = rearrange(x, 'n (h w) c -> n c h w', h=H, w=W)
        return x


def _grid2seq(x: Tensor, region_size: Tuple[int], num_heads: int):
    """
    Args:
        x: BCHW tensor
        region size: int
        num_heads: number of attention heads
    Return:
        out: rearranged x, has a shape of (bs, nhead, nregion, reg_size, head_dim)
        region_h, region_w: number of regions per col/row
    """
    B, C, H, W = x.size()
    region_h, region_w = H // region_size[0], W // region_size[1]
    x = x.view(B, num_heads, C // num_heads, region_h, region_size[0], region_w, region_size[1])
    x = torch.einsum('bmdhpwq->bmhwpqd', x).flatten(2, 3).flatten(-3, -2)  # (bs, nhead, nregion, reg_size, head_dim)
    return x, region_h, region_w


def _seq2grid(x: Tensor, region_h: int, region_w: int, region_size: Tuple[int]):
    """
    Args:
        x: (bs, nhead, nregion, reg_size^2, head_dim)
    Return:
        x: (bs, C, H, W)
    """
    bs, nhead, nregion, reg_size_square, head_dim = x.size()
    x = x.view(bs, nhead, region_h, region_w, region_size[0], region_size[1], head_dim)
    x = torch.einsum('bmhwpqd->bmdhpwq', x).reshape(bs, nhead * head_dim,
                                                    region_h * region_size[0], region_w * region_size[1])
    return x


def regional_routing_attention_torch(
        query: Tensor, key: Tensor, value: Tensor, scale: float,
        region_graph: LongTensor, region_size: Tuple[int],
        kv_region_size: Optional[Tuple[int]] = None,
        auto_pad=True) -> Tensor:
    """
    Args:
        query, key, value: (B, C, H, W) tensor
        scale: the scale/temperature for dot product attention
        region_graph: (B, nhead, h_q*w_q, topk) tensor, topk <= h_k*w_k
        region_size: region/window size for queries, (rh, rw)
        key_region_size: optional, if None, key_region_size=region_size
        auto_pad: required to be true if the input sizes are not divisible by the region_size
    Return:
        output: (B, C, H, W) tensor
        attn: (bs, nhead, q_nregion, reg_size, topk*kv_region_size) attention matrix
    """
    kv_region_size = kv_region_size or region_size
    bs, nhead, q_nregion, topk = region_graph.size()

    # Auto pad to deal with any input size
    q_pad_b, q_pad_r, kv_pad_b, kv_pad_r = 0, 0, 0, 0
    if auto_pad:
        _, _, Hq, Wq = query.size()
        q_pad_b = (region_size[0] - Hq % region_size[0]) % region_size[0]
        q_pad_r = (region_size[1] - Wq % region_size[1]) % region_size[1]
        if (q_pad_b > 0 or q_pad_r > 0):
            query = F.pad(query, (0, q_pad_r, 0, q_pad_b))  # zero padding

        _, _, Hk, Wk = key.size()
        kv_pad_b = (kv_region_size[0] - Hk % kv_region_size[0]) % kv_region_size[0]
        kv_pad_r = (kv_region_size[1] - Wk % kv_region_size[1]) % kv_region_size[1]
        if (kv_pad_r > 0 or kv_pad_b > 0):
            key = F.pad(key, (0, kv_pad_r, 0, kv_pad_b))  # zero padding
            value = F.pad(value, (0, kv_pad_r, 0, kv_pad_b))  # zero padding

    # to sequence format, i.e. (bs, nhead, nregion, reg_size, head_dim)
    query, q_region_h, q_region_w = _grid2seq(query, region_size=region_size, num_heads=nhead)
    key, _, _ = _grid2seq(key, region_size=kv_region_size, num_heads=nhead)
    value, _, _ = _grid2seq(value, region_size=kv_region_size, num_heads=nhead)

    # gather key and values.
    # TODO: is seperate gathering slower than fused one (our old version) ?
    # torch.gather does not support broadcasting, hence we do it manually
    bs, nhead, kv_nregion, kv_region_size, head_dim = key.size()
    broadcasted_region_graph = region_graph.view(bs, nhead, q_nregion, topk, 1, 1). \
        expand(-1, -1, -1, -1, kv_region_size, head_dim)
    key_g = torch.gather(key.view(bs, nhead, 1, kv_nregion, kv_region_size, head_dim). \
                         expand(-1, -1, query.size(2), -1, -1, -1), dim=3,
                         index=broadcasted_region_graph)  # (bs, nhead, q_nregion, topk, kv_region_size, head_dim)
    value_g = torch.gather(value.view(bs, nhead, 1, kv_nregion, kv_region_size, head_dim). \
                           expand(-1, -1, query.size(2), -1, -1, -1), dim=3,
                           index=broadcasted_region_graph)  # (bs, nhead, q_nregion, topk, kv_region_size, head_dim)

    # token-to-token attention
    # (bs, nhead, q_nregion, reg_size, head_dim) @ (bs, nhead, q_nregion, head_dim, topk*kv_region_size)
    # -> (bs, nhead, q_nregion, reg_size, topk*kv_region_size)
    # TODO: mask padding region
    attn = (query * scale) @ key_g.flatten(-3, -2).transpose(-1, -2)
    attn = torch.softmax(attn, dim=-1)
    # (bs, nhead, q_nregion, reg_size, topk*kv_region_size) @ (bs, nhead, q_nregion, topk*kv_region_size, head_dim)
    # -> (bs, nhead, q_nregion, reg_size, head_dim)
    output = attn @ value_g.flatten(-3, -2)

    # to BCHW format
    output = _seq2grid(output, region_h=q_region_h, region_w=q_region_w, region_size=region_size)

    # remove paddings if needed
    if auto_pad and (q_pad_b > 0 or q_pad_r > 0):
        output = output[:, :, :Hq, :Wq]

    return output, attn


class PSABlock_biformer(PSABlock):


    def __init__(self, c, qk_dim =16 , pdim=32, shortcut=True) -> None:
        """Initializes the PSABlock with attention and feed-forward layers for enhanced feature extraction."""
        super().__init__( c)

        self.attn = BiLevelRoutingAttention(c, qk_dim, pdim)



class C2PSA_biformer(C2PSA):

    def __init__(self, c1, c2, n=1, e=0.5):
        """Initializes the C2PSA module with specified input/output channels, number of layers, and expansion ratio."""
        super().__init__(c1, c2)
        assert c1 == c2
        self.c = int(c1 * e)

        self.m = nn.Sequential(*(PSABlock_biformer(self.c, qk_dim =16 , pdim=32) for _ in range(n)))



if __name__ =='__main__':

    IDC = BiLevelRoutingAttention(256)
    #创建一个输入张量
    batch_size = 8
    input_tensor=torch.randn(batch_size, 256, 64, 64 )
    #运行模型并打印输入和输出的形状
    output_tensor =IDC(input_tensor)
    print("Input shape:",input_tensor.shape)
    print("0utput shape:",output_tensor.shape)

 4. 将Biformer引入到YOLOv11中

第一: 将下面的核心代码复制到D:\bilibili\model\YOLO11\ultralytics-main\ultralytics\nn路径下,如下图所示。

第二:在task.py中导入C2PSA_biformer包

第三:在task.py中的模型配置部分下面代码

第四:将模型配置文件复制到YOLOV11.YAMY文件中

# Ultralytics YOLO 🚀, AGPL-3.0 license
# YOLO11 object detection model with P3-P5 outputs. For Usage examples see https://docs.ultralytics.com/tasks/detect

# Parameters
nc: 80 # number of classes
scales: # model compound scaling constants, i.e. 'model=yolo11n.yaml' will call yolo11.yaml with scale 'n'
  # [depth, width, max_channels]
  n: [0.50, 0.25, 1024] # summary: 319 layers, 2624080 parameters, 2624064 gradients, 6.6 GFLOPs
  s: [0.50, 0.50, 1024] # summary: 319 layers, 9458752 parameters, 9458736 gradients, 21.7 GFLOPs
  m: [0.50, 1.00, 512] # summary: 409 layers, 20114688 parameters, 20114672 gradients, 68.5 GFLOPs
  l: [1.00, 1.00, 512] # summary: 631 layers, 25372160 parameters, 25372144 gradients, 87.6 GFLOPs
  x: [1.00, 1.50, 512] # summary: 631 layers, 56966176 parameters, 56966160 gradients, 196.0 GFLOPs

# YOLO11n backbone
backbone:
  # [from, repeats, module, args]
  - [-1, 1, Conv, [64, 3, 2]] # 0-P1/2
  - [-1, 1, Conv, [128, 3, 2]] # 1-P2/4
  - [-1, 2, C3k2, [256, False, 0.25]]
  - [-1, 1, Conv, [256, 3, 2]] # 3-P3/8
  - [-1, 2, C3k2, [512, False, 0.25]]
  - [-1, 1, Conv, [512, 3, 2]] # 5-P4/16
  - [-1, 2, C3k2, [512, True]]
  - [-1, 1, Conv, [1024, 3, 2]] # 7-P5/32
  - [-1, 2, C3k2, [1024, True]]
  - [-1, 1, SPPF, [1024, 5]] # 9
  - [-1, 2, C2PSA_biformer, [1024]] # 10

# YOLO11n head
head:
  - [-1, 1, nn.Upsample, [None, 2, "nearest"]]
  - [[-1, 6], 1, Concat, [1]] # cat backbone P4
  - [-1, 2, C3k2, [512, False]] # 13

  - [-1, 1, nn.Upsample, [None, 2, "nearest"]]
  - [[-1, 4], 1, Concat, [1]] # cat backbone P3
  - [-1, 2, C3k2, [256, False]] # 16 (P3/8-small)

  - [-1, 1, Conv, [256, 3, 2]]
  - [[-1, 13], 1, Concat, [1]] # cat head P4
  - [-1, 2, C3k2, [512, False]] # 19 (P4/16-medium)

  - [-1, 1, Conv, [512, 3, 2]]
  - [[-1, 10], 1, Concat, [1]] # cat head P5
  - [-1, 2, C3k2, [1024, True]] # 22 (P5/32-large)

  - [[16, 19, 22], 1, Detect, [nc]] # Detect(P3, P4, P5)

第五:运行成功


from ultralytics.models import NAS, RTDETR, SAM, YOLO, FastSAM, YOLOWorld

if __name__=="__main__":


    # 使用自己的YOLOv11.yamy文件搭建模型并加载预训练权重训练模型
    model = YOLO(r"D:\bilibili\model\YOLO11\ultralytics-main\ultralytics\cfg\models\11\yolo11_biformer.yaml")\
        .load(r'D:\bilibili\model\YOLO11\ultralytics-main\yolo11n.pt')  # build from YAML and transfer weights

    results = model.train(data=r'D:\bilibili\model\ultralytics-main\ultralytics\cfg\datasets\VOC_my.yaml',
                          epochs=100, imgsz=640, batch=8)



 


原文地址:https://blog.csdn.net/qq_64693987/article/details/142990085

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