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原代码为mix_transformer 官方代码。
我改了一些地方做适配,目的是做研究,并了解一下mix_transformer.
原来的代码的segformer_head 的normalize那里的config的type是SyncBN,而这要求多GPU,我目前是单GPU,就改成了BN,在468行。
# --------------------------------------------------------------- # Copyright (c) 2021, NVIDIA Corporation. All rights reserved. # # This work is licensed under the NVIDIA Source Code License # --------------------------------------------------------------- import torch import torch.nn as nn import torch.nn.functional as F from functools import partial from timm.models.layers import DropPath, to_2tuple, trunc_normal_ from timm.models.registry import register_model from timm.models.vision_transformer import _cfg from mmseg.models.builder import BACKBONES from mmseg.utils import get_root_logger from mmcv.runner import load_checkpoint import math from mmcv.cnn import ConvModule, DepthwiseSeparableConvModule from mmseg.ops import resize class MLP(nn.Module): """ Linear Embedding """ def __init__(self, input_dim=2048, embed_dim=768): super().__init__() self.proj = nn.Linear(input_dim, embed_dim) def forward(self, x): x = x.flatten(2).transpose(1, 2) x = self.proj(x) return x class Mlp(nn.Module): def __init__(self, in_features, hidden_features=None, out_features=None, act_layer=nn.GELU, drop=0.): super().__init__() out_features = out_features or in_features hidden_features = hidden_features or in_features self.fc1 = nn.Linear(in_features, hidden_features) self.dwconv = DWConv(hidden_features) self.act = act_layer() self.fc2 = nn.Linear(hidden_features, out_features) self.drop = nn.Dropout(drop) self.apply(self._init_weights) def _init_weights(self, m): if isinstance(m, nn.Linear): trunc_normal_(m.weight, std=.02) if isinstance(m, nn.Linear) and m.bias is not None: nn.init.constant_(m.bias, 0) elif isinstance(m, nn.LayerNorm): nn.init.constant_(m.bias, 0) nn.init.constant_(m.weight, 1.0) elif isinstance(m, nn.Conv2d): fan_out = m.kernel_size[0] * m.kernel_size[1] * m.out_channels fan_out //= m.groups m.weight.data.normal_(0, math.sqrt(2.0 / fan_out)) if m.bias is not None: m.bias.data.zero_() def forward(self, x, H, W): x = self.fc1(x) x = self.dwconv(x, H, W) x = self.act(x) x = self.drop(x) x = self.fc2(x) x = self.drop(x) return x class Attention(nn.Module): def __init__(self, dim, num_heads=8, qkv_bias=False, qk_scale=None, attn_drop=0., proj_drop=0., sr_ratio=1): super().__init__() assert dim % num_heads == 0, f"dim {dim} should be divided by num_heads {num_heads}." self.dim = dim self.num_heads = num_heads head_dim = dim // num_heads self.scale = qk_scale or head_dim ** -0.5 self.q = nn.Linear(dim, dim, bias=qkv_bias) self.kv = nn.Linear(dim, dim * 2, bias=qkv_bias) self.attn_drop = nn.Dropout(attn_drop) self.proj = nn.Linear(dim, dim) self.proj_drop = nn.Dropout(proj_drop) self.sr_ratio = sr_ratio if sr_ratio > 1: self.sr = nn.Conv2d(dim, dim, kernel_size=sr_ratio, stride=sr_ratio) self.norm = nn.LayerNorm(dim) self.apply(self._init_weights) def _init_weights(self, m): if isinstance(m, nn.Linear): trunc_normal_(m.weight, std=.02) if isinstance(m, nn.Linear) and m.bias is not None: nn.init.constant_(m.bias, 0) elif isinstance(m, nn.LayerNorm): nn.init.constant_(m.bias, 0) nn.init.constant_(m.weight, 1.0) elif isinstance(m, nn.Conv2d): fan_out = m.kernel_size[0] * m.kernel_size[1] * m.out_channels fan_out //= m.groups m.weight.data.normal_(0, math.sqrt(2.0 / fan_out)) if m.bias is not None: m.bias.data.zero_() def forward(self, x, H, W): B, N, C = x.shape q = self.q(x).reshape(B, N, self.num_heads, C // self.num_heads).permute(0, 2, 1, 3) if self.sr_ratio > 1: x_ = x.permute(0, 2, 1).reshape(B, C, H, W) x_ = self.sr(x_).reshape(B, C, -1).permute(0, 2, 1) x_ = self.norm(x_) kv = self.kv(x_).reshape(B, -1, 2, self.num_heads, C // self.num_heads).permute(2, 0, 3, 1, 4) else: kv = self.kv(x).reshape(B, -1, 2, self.num_heads, C // self.num_heads).permute(2, 0, 3, 1, 4) k, v = kv[0], kv[1] 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) return x class Block(nn.Module): def __init__(self, dim, num_heads, mlp_ratio=4., qkv_bias=False, qk_scale=None, drop=0., attn_drop=0., drop_path=0., act_layer=nn.GELU, norm_layer=nn.LayerNorm, sr_ratio=1): super().__init__() self.norm1 = norm_layer(dim) self.attn = Attention( dim, num_heads=num_heads, qkv_bias=qkv_bias, qk_scale=qk_scale, attn_drop=attn_drop, proj_drop=drop, sr_ratio=sr_ratio) # NOTE: drop path for stochastic depth, we shall see if this is better than dropout here self.drop_path = DropPath(drop_path) if drop_path > 0. else nn.Identity() self.norm2 = norm_layer(dim) mlp_hidden_dim = int(dim * mlp_ratio) self.mlp = Mlp(in_features=dim, hidden_features=mlp_hidden_dim, act_layer=act_layer, drop=drop) self.apply(self._init_weights) def _init_weights(self, m): if isinstance(m, nn.Linear): trunc_normal_(m.weight, std=.02) if isinstance(m, nn.Linear) and m.bias is not None: nn.init.constant_(m.bias, 0) elif isinstance(m, nn.LayerNorm): nn.init.constant_(m.bias, 0) nn.init.constant_(m.weight, 1.0) elif isinstance(m, nn.Conv2d): fan_out = m.kernel_size[0] * m.kernel_size[1] * m.out_channels fan_out //= m.groups m.weight.data.normal_(0, math.sqrt(2.0 / fan_out)) if m.bias is not None: m.bias.data.zero_() def forward(self, x, H, W): x = x + self.drop_path(self.attn(self.norm1(x), H, W)) x = x + self.drop_path(self.mlp(self.norm2(x), H, W)) return x class OverlapPatchEmbed(nn.Module): """ Image to Patch Embedding """ def __init__(self, img_size=224, patch_size=7, stride=4, in_chans=3, embed_dim=768): super().__init__() img_size = to_2tuple(img_size) patch_size = to_2tuple(patch_size) # 7 -> (7, 7) self.img_size = img_size self.patch_size = patch_size self.H, self.W = img_size[0] // patch_size[0], img_size[1] // patch_size[1] self.num_patches = self.H * self.W self.proj = nn.Conv2d(in_chans, embed_dim, kernel_size=patch_size, stride=stride, padding=(patch_size[0] // 2, patch_size[1] // 2)) self.norm = nn.LayerNorm(embed_dim) self.apply(self._init_weights) def _init_weights(self, m): if isinstance(m, nn.Linear): trunc_normal_(m.weight, std=.02) if isinstance(m, nn.Linear) and m.bias is not None: nn.init.constant_(m.bias, 0) elif isinstance(m, nn.LayerNorm): nn.init.constant_(m.bias, 0) nn.init.constant_(m.weight, 1.0) elif isinstance(m, nn.Conv2d): fan_out = m.kernel_size[0] * m.kernel_size[1] * m.out_channels fan_out //= m.groups m.weight.data.normal_(0, math.sqrt(2.0 / fan_out)) if m.bias is not None: m.bias.data.zero_() def forward(self, x): x = self.proj(x) _, _, H, W = x.shape x = x.flatten(2).transpose(1, 2) # n c h w -> n c h*w -> n h*w c x = self.norm(x) # layer normalization return x, H, W # (n h*w c) h w class MixVisionTransformer(nn.Module): def __init__(self, img_size=224, patch_size=16, in_chans=3, num_classes=1000, embed_dims=[64, 128, 256, 512], num_heads=[1, 2, 4, 8], mlp_ratios=[4, 4, 4, 4], qkv_bias=False, qk_scale=None, drop_rate=0., attn_drop_rate=0., drop_path_rate=0., norm_layer=nn.LayerNorm, depths=[3, 4, 6, 3], sr_ratios=[8, 4, 2, 1]): super().__init__() self.num_classes = num_classes self.depths = depths # patch_embed self.patch_embed1 = OverlapPatchEmbed(img_size=img_size, patch_size=7, stride=4, in_chans=in_chans, embed_dim=embed_dims[0]) self.patch_embed2 = OverlapPatchEmbed(img_size=img_size // 4, patch_size=3, stride=2, in_chans=embed_dims[0], embed_dim=embed_dims[1]) self.patch_embed3 = OverlapPatchEmbed(img_size=img_size // 8, patch_size=3, stride=2, in_chans=embed_dims[1], embed_dim=embed_dims[2]) self.patch_embed4 = OverlapPatchEmbed(img_size=img_size // 16, patch_size=3, stride=2, in_chans=embed_dims[2], embed_dim=embed_dims[3]) # transformer encoder dpr = [x.item() for x in torch.linspace(0, drop_path_rate, sum(depths))] # stochastic depth decay rule cur = 0 self.block1 = nn.ModuleList([Block( dim=embed_dims[0], num_heads=num_heads[0], mlp_ratio=mlp_ratios[0], qkv_bias=qkv_bias, qk_scale=qk_scale, drop=drop_rate, attn_drop=attn_drop_rate, drop_path=dpr[cur + i], norm_layer=norm_layer, sr_ratio=sr_ratios[0]) for i in range(depths[0])]) self.norm1 = norm_layer(embed_dims[0]) cur += depths[0] self.block2 = nn.ModuleList([Block( dim=embed_dims[1], num_heads=num_heads[1], mlp_ratio=mlp_ratios[1], qkv_bias=qkv_bias, qk_scale=qk_scale, drop=drop_rate, attn_drop=attn_drop_rate, drop_path=dpr[cur + i], norm_layer=norm_layer, sr_ratio=sr_ratios[1]) for i in range(depths[1])]) self.norm2 = norm_layer(embed_dims[1]) cur += depths[1] self.block3 = nn.ModuleList([Block( dim=embed_dims[2], num_heads=num_heads[2], mlp_ratio=mlp_ratios[2], qkv_bias=qkv_bias, qk_scale=qk_scale, drop=drop_rate, attn_drop=attn_drop_rate, drop_path=dpr[cur + i], norm_layer=norm_layer, sr_ratio=sr_ratios[2]) for i in range(depths[2])]) self.norm3 = norm_layer(embed_dims[2]) cur += depths[2] self.block4 = nn.ModuleList([Block( dim=embed_dims[3], num_heads=num_heads[3], mlp_ratio=mlp_ratios[3], qkv_bias=qkv_bias, qk_scale=qk_scale, drop=drop_rate, attn_drop=attn_drop_rate, drop_path=dpr[cur + i], norm_layer=norm_layer, sr_ratio=sr_ratios[3]) for i in range(depths[3])]) self.norm4 = norm_layer(embed_dims[3]) # classification head # self.head = nn.Linear(embed_dims[3], num_classes) if num_classes > 0 else nn.Identity() self.apply(self._init_weights) def _init_weights(self, m): if isinstance(m, nn.Linear): trunc_normal_(m.weight, std=.02) if isinstance(m, nn.Linear) and m.bias is not None: nn.init.constant_(m.bias, 0) elif isinstance(m, nn.LayerNorm): nn.init.constant_(m.bias, 0) nn.init.constant_(m.weight, 1.0) elif isinstance(m, nn.Conv2d): fan_out = m.kernel_size[0] * m.kernel_size[1] * m.out_channels fan_out //= m.groups m.weight.data.normal_(0, math.sqrt(2.0 / fan_out)) if m.bias is not None: m.bias.data.zero_() def init_weights(self, pretrained=None): if isinstance(pretrained, str): logger = get_root_logger() load_checkpoint(self, pretrained, map_location='cpu', strict=False, logger=logger) def reset_drop_path(self, drop_path_rate): dpr = [x.item() for x in torch.linspace(0, drop_path_rate, sum(self.depths))] cur = 0 for i in range(self.depths[0]): self.block1[i].drop_path.drop_prob = dpr[cur + i] cur += self.depths[0] for i in range(self.depths[1]): self.block2[i].drop_path.drop_prob = dpr[cur + i] cur += self.depths[1] for i in range(self.depths[2]): self.block3[i].drop_path.drop_prob = dpr[cur + i] cur += self.depths[2] for i in range(self.depths[3]): self.block4[i].drop_path.drop_prob = dpr[cur + i] def freeze_patch_emb(self): self.patch_embed1.requires_grad = False @torch.jit.ignore def no_weight_decay(self): return {'pos_embed1', 'pos_embed2', 'pos_embed3', 'pos_embed4', 'cls_token'} # has pos_embed may be better def get_classifier(self): return self.head def reset_classifier(self, num_classes, global_pool=''): self.num_classes = num_classes self.head = nn.Linear(self.embed_dim, num_classes) if num_classes > 0 else nn.Identity() def forward_features(self, x): B = x.shape[0] outs = [] # stage 1 x, H, W = self.patch_embed1(x) # (n h*w c) h w # print("stage 1, x.shape:{}, h:{}, w:{}".format(x.shape, H, W)) for i, blk in enumerate(self.block1): x = blk(x, H, W) x = self.norm1(x) x = x.reshape(B, H, W, -1).permute(0, 3, 1, 2).contiguous() outs.append(x) # stage 2 x, H, W = self.patch_embed2(x) for i, blk in enumerate(self.block2): x = blk(x, H, W) x = self.norm2(x) x = x.reshape(B, H, W, -1).permute(0, 3, 1, 2).contiguous() outs.append(x) # stage 3 x, H, W = self.patch_embed3(x) for i, blk in enumerate(self.block3): x = blk(x, H, W) x = self.norm3(x) x = x.reshape(B, H, W, -1).permute(0, 3, 1, 2).contiguous() outs.append(x) # stage 4 x, H, W = self.patch_embed4(x) for i, blk in enumerate(self.block4): x = blk(x, H, W) x = self.norm4(x) x = x.reshape(B, H, W, -1).permute(0, 3, 1, 2).contiguous() outs.append(x) return outs def forward(self, x): print("x.shape:{}".format(x.shape)) x = self.forward_features(x) # x = self.head(x) return x class DWConv(nn.Module): def __init__(self, dim=768): super(DWConv, self).__init__() self.dwconv = nn.Conv2d(dim, dim, 3, 1, 1, bias=True, groups=dim) def forward(self, x, H, W): B, N, C = x.shape x = x.transpose(1, 2).view(B, C, H, W) x = self.dwconv(x) x = x.flatten(2).transpose(1, 2) return x @BACKBONES.register_module() class mit_b0(MixVisionTransformer): def __init__(self, **kwargs): super(mit_b0, self).__init__( patch_size=4, embed_dims=[32, 64, 160, 256], num_heads=[1, 2, 5, 8], mlp_ratios=[4, 4, 4, 4], qkv_bias=True, norm_layer=partial(nn.LayerNorm, eps=1e-6), depths=[2, 2, 2, 2], sr_ratios=[8, 4, 2, 1], drop_rate=0.0, drop_path_rate=0.1) @BACKBONES.register_module() class mit_b1(MixVisionTransformer): def __init__(self, **kwargs): super(mit_b1, self).__init__( patch_size=4, embed_dims=[64, 128, 320, 512], num_heads=[1, 2, 5, 8], mlp_ratios=[4, 4, 4, 4], qkv_bias=True, norm_layer=partial(nn.LayerNorm, eps=1e-6), depths=[2, 2, 2, 2], sr_ratios=[8, 4, 2, 1], drop_rate=0.0, drop_path_rate=0.1) @BACKBONES.register_module() class mit_b2(MixVisionTransformer): def __init__(self, **kwargs): super(mit_b2, self).__init__( patch_size=4, embed_dims=[64, 128, 320, 512], num_heads=[1, 2, 5, 8], mlp_ratios=[4, 4, 4, 4], qkv_bias=True, norm_layer=partial(nn.LayerNorm, eps=1e-6), depths=[3, 4, 6, 3], sr_ratios=[8, 4, 2, 1], drop_rate=0.0, drop_path_rate=0.1) @BACKBONES.register_module() class mit_b3(MixVisionTransformer): def __init__(self, **kwargs): super(mit_b3, self).__init__( patch_size=4, embed_dims=[64, 128, 320, 512], num_heads=[1, 2, 5, 8], mlp_ratios=[4, 4, 4, 4], qkv_bias=True, norm_layer=partial(nn.LayerNorm, eps=1e-6), depths=[3, 4, 18, 3], sr_ratios=[8, 4, 2, 1], drop_rate=0.0, drop_path_rate=0.1) @BACKBONES.register_module() class mit_b4(MixVisionTransformer): def __init__(self, **kwargs): super(mit_b4, self).__init__( patch_size=4, embed_dims=[64, 128, 320, 512], num_heads=[1, 2, 5, 8], mlp_ratios=[4, 4, 4, 4], qkv_bias=True, norm_layer=partial(nn.LayerNorm, eps=1e-6), depths=[3, 8, 27, 3], sr_ratios=[8, 4, 2, 1], drop_rate=0.0, drop_path_rate=0.1) @BACKBONES.register_module() class mit_b5(MixVisionTransformer): def __init__(self, **kwargs): super(mit_b5, self).__init__( patch_size=4, embed_dims=[64, 128, 320, 512], num_heads=[1, 2, 5, 8], mlp_ratios=[4, 4, 4, 4], qkv_bias=True, norm_layer=partial(nn.LayerNorm, eps=1e-6), depths=[3, 6, 40, 3], sr_ratios=[8, 4, 2, 1], drop_rate=0.0, drop_path_rate=0.1) class SegFormerHead(nn.Module): """ SegFormer: Simple and Efficient Design for Semantic Segmentation with Transformers """ def __init__(self, feature_strides, in_channels, embedding_dim, input_transform='multiple_select', in_index=[0, 1, 2, 3], dropout_ratio=0.1, num_classes=4): super(SegFormerHead, self).__init__() # input_transform='multiple_select' self.feature_strides = feature_strides self.input_transform = input_transform self.in_index = in_index c1_in_channels, c2_in_channels, c3_in_channels, c4_in_channels = in_channels self.linear_c4 = MLP(input_dim=c4_in_channels, embed_dim=embedding_dim) self.linear_c3 = MLP(input_dim=c3_in_channels, embed_dim=embedding_dim) self.linear_c2 = MLP(input_dim=c2_in_channels, embed_dim=embedding_dim) self.linear_c1 = MLP(input_dim=c1_in_channels, embed_dim=embedding_dim) self.linear_fuse = ConvModule( in_channels=embedding_dim*4, out_channels=embedding_dim, kernel_size=1, norm_cfg=dict(type='BN', requires_grad=True) # type='SyncBN'-> type='BN' ) self.linear_pred = nn.Conv2d(embedding_dim, num_classes, kernel_size=1) self.dropout = nn.Dropout2d(dropout_ratio) def _transform_inputs(self, inputs): """Transform inputs for decoder. Args: inputs (list[Tensor]): List of multi-level img features. Returns: Tensor: The transformed inputs """ if self.input_transform == 'resize_concat': inputs = [inputs[i] for i in self.in_index] upsampled_inputs = [ resize( input=x, size=inputs[0].shape[2:], mode='bilinear', align_corners=self.align_corners) for x in inputs ] inputs = torch.cat(upsampled_inputs, dim=1) elif self.input_transform == 'multiple_select': inputs = [inputs[i] for i in self.in_index] else: inputs = inputs[self.in_index] return inputs def forward(self, inputs): x = self._transform_inputs(inputs) # len=4, 1/4,1/8,1/16,1/32 c1, c2, c3, c4 = x ############## MLP decoder on C1-C4 ########### n, _, h, w = c4.shape _c4 = self.linear_c4(c4).permute(0,2,1).reshape(n, -1, c4.shape[2], c4.shape[3]) _c4 = resize(_c4, size=c1.size()[2:],mode='bilinear',align_corners=False) _c3 = self.linear_c3(c3).permute(0,2,1).reshape(n, -1, c3.shape[2], c3.shape[3]) _c3 = resize(_c3, size=c1.size()[2:],mode='bilinear',align_corners=False) _c2 = self.linear_c2(c2).permute(0,2,1).reshape(n, -1, c2.shape[2], c2.shape[3]) _c2 = resize(_c2, size=c1.size()[2:],mode='bilinear',align_corners=False) _c1 = self.linear_c1(c1).permute(0,2,1).reshape(n, -1, c1.shape[2], c1.shape[3]) _c = self.linear_fuse(torch.cat([_c4, _c3, _c2, _c1], dim=1)) x = self.dropout(_c) x = self.linear_pred(x) # x = x.clamp(0., 1.) return x mitb1 = mit_b1().cuda() n, c, h, w = 2, 3, 512, 512 x = torch.randn((n, c, h, w), dtype=torch.float32) x = x.cuda() y = mitb1.forward(x) # print(y[0].shape) # print(y[1].shape) # print(y[2].shape) # print(y[3].shape) # x.shape:torch.Size([2, 3, 512, 512]) # torch.Size([2, 64, 128, 128]) # torch.Size([2, 128, 64, 64]) # torch.Size([2, 320, 32, 32]) # torch.Size([2, 512, 16, 16]) decoder = SegFormerHead(feature_strides=[4, 8, 16, 32], in_channels=[64, 128, 320, 512], embedding_dim=256) decoder = decoder.cuda() y = decoder.forward(y) print(y.shape) # torch.Size([2, 4, 128, 128])
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