mirror of https://github.com/YifanXu74/MQ-Det.git
861 lines
35 KiB
Python
861 lines
35 KiB
Python
# --------------------------------------------------------
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# Swin Transformer
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# modified from https://github.com/SwinTransformer/Swin-Transformer-Object-Detection/blob/master/mmdet/models/backbones/swin_transformer.py
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# --------------------------------------------------------
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import torch
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import torch.nn as nn
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import torch.nn.functional as F
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import torch.utils.checkpoint as checkpoint
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import numpy as np
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from einops import rearrange
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from timm.models.layers import DropPath, to_2tuple, trunc_normal_
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class Mlp(nn.Module):
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""" Multilayer perceptron."""
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def __init__(self, in_features, hidden_features=None, out_features=None, act_layer=nn.GELU, drop=0.):
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super().__init__()
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out_features = out_features or in_features
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hidden_features = hidden_features or in_features
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self.fc1 = nn.Linear(in_features, hidden_features)
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self.act = act_layer()
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self.fc2 = nn.Linear(hidden_features, out_features)
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self.drop = nn.Dropout(drop)
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def forward(self, x):
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x = self.fc1(x)
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x = self.act(x)
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x = self.drop(x)
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x = self.fc2(x)
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x = self.drop(x)
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return x
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def window_partition(x, window_size):
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"""
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Args:
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x: (B, H, W, C)
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window_size (int): window size
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Returns:
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windows: (num_windows*B, window_size, window_size, C)
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"""
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B, H, W, C = x.shape
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x = x.view(B, H // window_size, window_size, W // window_size, window_size, C)
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windows = x.permute(0, 1, 3, 2, 4, 5).contiguous().view(-1, window_size, window_size, C)
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return windows
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def window_reverse(windows, window_size, H, W):
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"""
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Args:
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windows: (num_windows*B, window_size, window_size, C)
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window_size (int): Window size
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H (int): Height of image
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W (int): Width of image
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Returns:
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x: (B, H, W, C)
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"""
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B = int(windows.shape[0] / (H * W / window_size / window_size))
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x = windows.view(B, H // window_size, W // window_size, window_size, window_size, -1)
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x = x.permute(0, 1, 3, 2, 4, 5).contiguous().view(B, H, W, -1)
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return x
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class WindowAttention(nn.Module):
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""" Window based multi-head self attention (W-MSA) module with relative position bias.
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It supports both of shifted and non-shifted window.
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Args:
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dim (int): Number of input channels.
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window_size (tuple[int]): The height and width of the window.
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num_heads (int): Number of attention heads.
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qkv_bias (bool, optional): If True, add a learnable bias to query, key, value. Default: True
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qk_scale (float | None, optional): Override default qk scale of head_dim ** -0.5 if set
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attn_drop (float, optional): Dropout ratio of attention weight. Default: 0.0
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proj_drop (float, optional): Dropout ratio of output. Default: 0.0
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"""
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def __init__(self, dim, window_size, num_heads, qkv_bias=True, qk_scale=None, attn_drop=0., proj_drop=0.,
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ntext=None, dim_text=None):
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super().__init__()
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self.dim = dim
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self.window_size = window_size # Wh, Ww
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self.num_heads = num_heads
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head_dim = dim // num_heads
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self.scale = qk_scale or head_dim ** -0.5
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# define a parameter table of relative position bias
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self.relative_position_bias_table = nn.Parameter(
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torch.zeros((2 * window_size[0] - 1) * (2 * window_size[1] - 1), num_heads)) # 2*Wh-1 * 2*Ww-1, nH
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# get pair-wise relative position index for each token inside the window
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coords_h = torch.arange(self.window_size[0])
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coords_w = torch.arange(self.window_size[1])
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coords = torch.stack(torch.meshgrid([coords_h, coords_w])) # 2, Wh, Ww
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coords_flatten = torch.flatten(coords, 1) # 2, Wh*Ww
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relative_coords = coords_flatten[:, :, None] - coords_flatten[:, None, :] # 2, Wh*Ww, Wh*Ww
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relative_coords = relative_coords.permute(1, 2, 0).contiguous() # Wh*Ww, Wh*Ww, 2
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relative_coords[:, :, 0] += self.window_size[0] - 1 # shift to start from 0
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relative_coords[:, :, 1] += self.window_size[1] - 1
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relative_coords[:, :, 0] *= 2 * self.window_size[1] - 1
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relative_position_index = relative_coords.sum(-1) # Wh*Ww, Wh*Ww
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self.register_buffer("relative_position_index", relative_position_index)
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self.qkv = nn.Linear(dim, dim * 3, bias=qkv_bias)
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self.attn_drop = nn.Dropout(attn_drop)
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self.proj = nn.Linear(dim, dim)
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self.proj_drop = nn.Dropout(proj_drop)
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trunc_normal_(self.relative_position_bias_table, std=.02)
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self.softmax = nn.Softmax(dim=-1)
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if ntext is not None:
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self.qkv_text = nn.Linear(dim_text, dim * 3, bias=qkv_bias)
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self.proj_text = nn.Linear(dim, dim_text)
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self.i2t_relative_position_bias = nn.Parameter(
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torch.zeros(2, num_heads, ntext)) # (2, nH, ntext)
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self.t2t_relative_position_bias = nn.Parameter(
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torch.zeros(num_heads, ntext, ntext)) # (nH, ntext, ntext)
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trunc_normal_(self.i2t_relative_position_bias, std=.02)
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trunc_normal_(self.t2t_relative_position_bias, std=.02)
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def forward(self, x, mask=None, x_text=None, mask_text=None):
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""" Forward function.
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Args:
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x: input features with shape of (num_windows*B, N, C)
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mask: (0/-inf) mask with shape of (num_windows, Wh*Ww, Wh*Ww) or None
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x_text: input text features with shape of (B_text, N_text, C_text)
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mask_text: (0/-inf) mask with shape of (B_text, N_text) or None; TODO: support casual mask
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"""
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B_, N, C = x.shape
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qkv = self.qkv(x).reshape(B_, N, 3, self.num_heads, C // self.num_heads).permute(2, 0, 3, 1, 4)
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q, k, v = qkv[0], qkv[1], qkv[2] # make torchscript happy (cannot use tensor as tuple)
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q = q * self.scale
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attn = (q @ k.transpose(-2, -1))
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relative_position_bias = self.relative_position_bias_table[self.relative_position_index.view(-1)].view(
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self.window_size[0] * self.window_size[1], self.window_size[0] * self.window_size[1], -1) # Wh*Ww,Wh*Ww,nH
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relative_position_bias = relative_position_bias.permute(2, 0, 1).contiguous() # nH, Wh*Ww, Wh*Ww
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attn = attn + relative_position_bias.unsqueeze(0)
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if mask is not None:
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nW = mask.shape[0]
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attn = attn.view(B_ // nW, nW, self.num_heads, N, N) + mask.unsqueeze(1).unsqueeze(0)
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attn = attn.view(-1, self.num_heads, N, N)
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if x_text is not None:
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B_text, N_text, C_text = x_text.shape
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nW = B_ // B_text # number of windows
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assert B_text * nW == B_, "B_ is not a multiplier of B_text in window attention"
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# notice that after qkv_text, the hidden dimension is C instead of C_text
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qkv_text = self.qkv_text(x_text).reshape(B_text, N_text, 3, self.num_heads, C // self.num_heads).permute(2, 0, 3,
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1, 4)
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q_text, k_text, v_text = qkv_text[0], qkv_text[1], qkv_text[
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2] # make torchscript happy (cannot use tensor as tuple)
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# image to text attention
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attn_i2t = (q @ torch.repeat_interleave(k_text, nW, dim=0).transpose(-2, -1)) # B_, nH, N, N_text
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# add image to text bias and text_mask
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if mask_text is not None:
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mask_and_i2t_bias = mask_text.view(B_text, 1, 1, N_text) + self.i2t_relative_position_bias[:1].expand(
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B_text, -1, -1).unsqueeze(-2) # B_text, nH, 1, N_text
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else:
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mask_and_i2t_bias = self.i2t_relative_position_bias[:1].expand(B_text, -1, -1).unsqueeze(
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-2) # B_text, nH, 1, N_text
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attn_i2t = attn_i2t + torch.repeat_interleave(mask_and_i2t_bias, nW, dim=0)
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attn = torch.cat((attn, attn_i2t), dim=-1) # B_, nH, N, N+N_text
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attn = self.softmax(attn)
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attn = self.attn_drop(attn)
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if x_text is None:
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x = (attn @ v).transpose(1, 2).reshape(B_, N, C)
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else:
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x = (
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attn @ torch.cat((v, torch.repeat_interleave(v_text, nW, dim=0)), dim=-2)
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).transpose(1, 2).reshape(B_, N, C)
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# compute attn_t2i
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q_text = q_text * self.scale
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kv = qkv[1:].reshape(2, B_text, nW, self.num_heads, N, C // self.num_heads).transpose(2, 3)
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k, v = kv[0].reshape(B_text, self.num_heads, nW * N, -1), kv[1].reshape(B_text, self.num_heads, nW * N, -1)
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attn_t2i = (q_text @ k.transpose(-2, -1))
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mask_t2i = self.i2t_relative_position_bias[1:].expand(B_text, -1, -1).unsqueeze(-1) # B_text, nH, N_text, 1
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attn_t2i = attn_t2i + mask_t2i
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attn_t2t = (q_text @ k_text.transpose(-2, -1))
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# add relative positional bias
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attn_t2t = attn_t2t + self.t2t_relative_position_bias.unsqueeze(0)
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if mask_text is not None:
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attn_t2t = attn_t2t + mask_text.view(B_text, 1, 1, N_text)
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attn_t = torch.cat((attn_t2i, attn_t2t), dim=-1) # B_text, nH, N_text, N+N_text
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attn_t = self.softmax(attn_t)
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attn_t = self.attn_drop(attn_t)
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x_text = (
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attn_t @ torch.cat((v, v_text), dim=-2)
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).transpose(1, 2).reshape(B_text, N_text, C)
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x_text = self.proj_text(x_text)
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x_text = self.proj_drop(x_text)
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x = self.proj(x)
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x = self.proj_drop(x)
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return x, x_text
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class SwinTransformerBlock(nn.Module):
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""" Swin Transformer Block.
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Args:
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dim (int): Number of input channels.
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num_heads (int): Number of attention heads.
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window_size (int): Window size.
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shift_size (int): Shift size for SW-MSA.
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mlp_ratio (float): Ratio of mlp hidden dim to embedding dim.
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qkv_bias (bool, optional): If True, add a learnable bias to query, key, value. Default: True
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qk_scale (float | None, optional): Override default qk scale of head_dim ** -0.5 if set.
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drop (float, optional): Dropout rate. Default: 0.0
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attn_drop (float, optional): Attention dropout rate. Default: 0.0
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drop_path (float, optional): Stochastic depth rate. Default: 0.0
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act_layer (nn.Module, optional): Activation layer. Default: nn.GELU
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norm_layer (nn.Module, optional): Normalization layer. Default: nn.LayerNorm
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"""
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def __init__(self, dim, num_heads, window_size=7, shift_size=0,
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mlp_ratio=4., qkv_bias=True, qk_scale=None, drop=0., attn_drop=0., drop_path=0.,
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act_layer=nn.GELU, norm_layer=nn.LayerNorm, layer_scale=False, ntext=None, dim_text=None):
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super().__init__()
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self.dim = dim
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self.num_heads = num_heads
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self.window_size = window_size
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self.shift_size = shift_size
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self.mlp_ratio = mlp_ratio
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assert 0 <= self.shift_size < self.window_size, "shift_size must in 0-window_size"
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self.norm1 = norm_layer(dim)
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self.attn = WindowAttention(
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dim, window_size=to_2tuple(self.window_size), num_heads=num_heads,
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qkv_bias=qkv_bias, qk_scale=qk_scale, attn_drop=attn_drop, proj_drop=drop,
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ntext=ntext, dim_text=dim_text
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)
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self.drop_path = DropPath(drop_path) if drop_path > 0. else nn.Identity()
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self.norm2 = norm_layer(dim)
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mlp_hidden_dim = int(dim * mlp_ratio)
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self.mlp = Mlp(in_features=dim, hidden_features=mlp_hidden_dim, act_layer=act_layer, drop=drop)
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self.H = None
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self.W = None
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self.gamma = 1.0
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if layer_scale:
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self.gamma = nn.Parameter(
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1e-4*torch.ones(dim), requires_grad=True
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)
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if dim_text is not None:
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self.norm1_text = norm_layer(dim_text)
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self.norm2_text = norm_layer(dim_text)
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mlp_hidden_dim_text = int(dim_text * mlp_ratio)
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self.mlp_text = Mlp(in_features=dim_text, hidden_features=mlp_hidden_dim_text, act_layer=act_layer,
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drop=drop)
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self.gamma_text = 1.0
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if layer_scale:
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self.gamma_text = nn.Parameter(
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1e-4*torch.ones(dim_text), requires_grad=True
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)
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def forward(self, x, mask_matrix, x_text, mask_text):
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""" Forward function.
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Args:
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x: Input feature, tensor size (B, H*W, C).
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H, W: Spatial resolution of the input feature.
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mask_matrix: Attention mask for cyclic shift.
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x_text: Input text feature, tensor size (B, L_text, C_text). L_text: Number of text tokens.
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mask_text: text mask (vector right now).
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"""
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B, L, C = x.shape
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H, W = self.H, self.W
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assert L == H * W, "input feature has wrong size"
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if x_text is not None:
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B, L_text, C_text = x_text.shape
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shortcut_text = x_text
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x_text = self.norm1_text(x_text)
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shortcut = x
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x = self.norm1(x)
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x = x.view(B, H, W, C)
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# pad feature maps to multiples of window size
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pad_l = pad_t = 0
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pad_r = (self.window_size - W % self.window_size) % self.window_size
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pad_b = (self.window_size - H % self.window_size) % self.window_size
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x = F.pad(x, (0, 0, pad_l, pad_r, pad_t, pad_b))
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_, Hp, Wp, _ = x.shape
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# cyclic shift
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if self.shift_size > 0:
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shifted_x = torch.roll(x, shifts=(-self.shift_size, -self.shift_size), dims=(1, 2))
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attn_mask = mask_matrix
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else:
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shifted_x = x
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attn_mask = None
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# partition windows
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x_windows = window_partition(shifted_x, self.window_size) # nW*B, window_size, window_size, C
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x_windows = x_windows.view(-1, self.window_size * self.window_size, C) # nW*B, window_size*window_size, C
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# W-MSA/SW-MSA
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attn_windows, x_text = self.attn(x_windows, mask=attn_mask, x_text=x_text,
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mask_text=mask_text) # nW*B, window_size*window_size, C
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# merge windows
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attn_windows = attn_windows.view(-1, self.window_size, self.window_size, C)
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shifted_x = window_reverse(attn_windows, self.window_size, Hp, Wp) # B H' W' C
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# reverse cyclic shift
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if self.shift_size > 0:
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x = torch.roll(shifted_x, shifts=(self.shift_size, self.shift_size), dims=(1, 2))
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else:
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x = shifted_x
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if pad_r > 0 or pad_b > 0:
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x = x[:, :H, :W, :].contiguous()
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x = x.view(B, H * W, C)
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# FFN
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x = shortcut + self.drop_path(self.gamma*x)
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x = x + self.drop_path(self.gamma*self.mlp(self.norm2(x)))
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if x_text is not None:
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x_text = shortcut_text + self.drop_path(self.gamma_text*x_text)
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x_text = x_text + self.drop_path(self.gamma_text*self.mlp_text(self.norm2_text(x_text)))
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return x, x_text
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class PatchMerging(nn.Module):
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""" Patch Merging Layer
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Args:
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dim (int): Number of input channels.
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norm_layer (nn.Module, optional): Normalization layer. Default: nn.LayerNorm
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"""
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def __init__(self, dim, norm_layer=nn.LayerNorm):
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super().__init__()
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self.dim = dim
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self.reduction = nn.Linear(4 * dim, 2 * dim, bias=False)
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self.norm = norm_layer(4 * dim)
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def forward(self, x, H, W):
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""" Forward function.
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Args:
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x: Input feature, tensor size (B, H*W, C).
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H, W: Spatial resolution of the input feature.
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"""
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B, L, C = x.shape
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assert L == H * W, "input feature has wrong size"
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x = x.view(B, H, W, C)
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# padding
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pad_input = (H % 2 == 1) or (W % 2 == 1)
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if pad_input:
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x = F.pad(x, (0, 0, 0, W % 2, 0, H % 2))
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x0 = x[:, 0::2, 0::2, :] # B H/2 W/2 C
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x1 = x[:, 1::2, 0::2, :] # B H/2 W/2 C
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x2 = x[:, 0::2, 1::2, :] # B H/2 W/2 C
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x3 = x[:, 1::2, 1::2, :] # B H/2 W/2 C
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x = torch.cat([x0, x1, x2, x3], -1) # B H/2 W/2 4*C
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x = x.view(B, -1, 4 * C) # B H/2*W/2 4*C
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x = self.norm(x)
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x = self.reduction(x)
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return x
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class BasicLayer(nn.Module):
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""" A basic Swin Transformer layer for one stage.
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Args:
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dim (int): Number of feature channels
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depth (int): Depths of this stage.
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num_heads (int): Number of attention head.
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window_size (int): Local window size. Default: 7.
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mlp_ratio (float): Ratio of mlp hidden dim to embedding dim. Default: 4.
|
|
qkv_bias (bool, optional): If True, add a learnable bias to query, key, value. Default: True
|
|
qk_scale (float | None, optional): Override default qk scale of head_dim ** -0.5 if set.
|
|
drop (float, optional): Dropout rate. Default: 0.0
|
|
attn_drop (float, optional): Attention dropout rate. Default: 0.0
|
|
drop_path (float | tuple[float], optional): Stochastic depth rate. Default: 0.0
|
|
norm_layer (nn.Module, optional): Normalization layer. Default: nn.LayerNorm
|
|
downsample (nn.Module | None, optional): Downsample layer at the end of the layer. Default: None
|
|
use_checkpoint (bool): Whether to use checkpointing to save memory. Default: False.
|
|
"""
|
|
|
|
def __init__(self,
|
|
dim,
|
|
depth,
|
|
num_heads,
|
|
window_size=7,
|
|
mlp_ratio=4.,
|
|
qkv_bias=True,
|
|
qk_scale=None,
|
|
drop=0.,
|
|
attn_drop=0.,
|
|
drop_path=0.,
|
|
norm_layer=nn.LayerNorm,
|
|
downsample=None,
|
|
use_checkpoint=False,
|
|
layer_scale=False,
|
|
ntext=None,
|
|
dim_text=None):
|
|
super().__init__()
|
|
self.window_size = window_size
|
|
self.shift_size = window_size // 2
|
|
self.depth = depth
|
|
self.use_checkpoint = use_checkpoint
|
|
|
|
# build blocks
|
|
self.blocks = nn.ModuleList([
|
|
SwinTransformerBlock(
|
|
dim=dim,
|
|
num_heads=num_heads,
|
|
window_size=window_size,
|
|
shift_size=0 if (i % 2 == 0) else window_size // 2,
|
|
mlp_ratio=mlp_ratio,
|
|
qkv_bias=qkv_bias,
|
|
qk_scale=qk_scale,
|
|
drop=drop,
|
|
attn_drop=attn_drop,
|
|
drop_path=drop_path[i] if isinstance(drop_path, list) else drop_path,
|
|
norm_layer=norm_layer,
|
|
layer_scale=layer_scale,
|
|
ntext=ntext,
|
|
dim_text=dim_text)
|
|
for i in range(depth)])
|
|
|
|
# patch merging layer
|
|
if downsample is not None:
|
|
self.downsample = downsample(patch_size=3, in_chans=dim, embed_dim=dim*2,
|
|
stride=2, padding=1, norm_layer=norm_layer)
|
|
else:
|
|
self.downsample = None
|
|
|
|
def forward(self, x, H, W, x_text=None, mask_text=None):
|
|
""" Forward function.
|
|
Args:
|
|
x: Input feature, tensor size (B, H*W, C).
|
|
H, W: Spatial resolution of the input feature.
|
|
x_text: input text features with shape of (B_text, N_text, C_text)
|
|
mask_text: (0/-inf) mask with shape of (B_text, N_text) or None;
|
|
"""
|
|
|
|
# calculate attention mask for SW-MSA
|
|
Hp = int(np.ceil(H / self.window_size)) * self.window_size
|
|
Wp = int(np.ceil(W / self.window_size)) * self.window_size
|
|
img_mask = torch.zeros((1, Hp, Wp, 1), device=x.device) # 1 Hp Wp 1
|
|
h_slices = (slice(0, -self.window_size),
|
|
slice(-self.window_size, -self.shift_size),
|
|
slice(-self.shift_size, None))
|
|
w_slices = (slice(0, -self.window_size),
|
|
slice(-self.window_size, -self.shift_size),
|
|
slice(-self.shift_size, None))
|
|
cnt = 0
|
|
for h in h_slices:
|
|
for w in w_slices:
|
|
img_mask[:, h, w, :] = cnt
|
|
cnt += 1
|
|
|
|
mask_windows = window_partition(img_mask, self.window_size) # nW, window_size, window_size, 1
|
|
mask_windows = mask_windows.view(-1, self.window_size * self.window_size)
|
|
attn_mask = mask_windows.unsqueeze(1) - mask_windows.unsqueeze(2)
|
|
attn_mask = attn_mask.masked_fill(attn_mask != 0, float(-100.0)).masked_fill(attn_mask == 0, float(0.0))
|
|
|
|
for blk in self.blocks:
|
|
blk.H, blk.W = H, W
|
|
if self.use_checkpoint:
|
|
x, x_text = checkpoint.checkpoint(blk, x, attn_mask, x_text, mask_text)
|
|
else:
|
|
x, x_text = blk(x, attn_mask, x_text, mask_text)
|
|
if self.downsample is not None:
|
|
x_down = self.downsample(x, H, W)
|
|
Wh, Ww = (H + 1) // 2, (W + 1) // 2
|
|
return x, H, W, x_down, Wh, Ww, x_text
|
|
else:
|
|
return x, H, W, x, H, W, x_text
|
|
|
|
|
|
# class PatchEmbed(nn.Module):
|
|
# """ Image to Patch Embedding
|
|
# Args:
|
|
# patch_size (int): Patch token size. Default: 4.
|
|
# in_chans (int): Number of input image channels. Default: 3.
|
|
# embed_dim (int): Number of linear projection output channels. Default: 96.
|
|
# norm_layer (nn.Module, optional): Normalization layer. Default: None
|
|
# """
|
|
#
|
|
# def __init__(self, patch_size=4, in_chans=3, embed_dim=96, norm_layer=None):
|
|
# super().__init__()
|
|
# patch_size = to_2tuple(patch_size)
|
|
# self.patch_size = patch_size
|
|
#
|
|
# self.in_chans = in_chans
|
|
# self.embed_dim = embed_dim
|
|
#
|
|
# self.proj = nn.Conv2d(in_chans, embed_dim, kernel_size=patch_size, stride=patch_size)
|
|
# if norm_layer is not None:
|
|
# self.norm = norm_layer(embed_dim)
|
|
# else:
|
|
# self.norm = None
|
|
#
|
|
# def forward(self, x):
|
|
# """Forward function."""
|
|
# # padding
|
|
# _, _, H, W = x.size()
|
|
# if W % self.patch_size[1] != 0:
|
|
# x = F.pad(x, (0, self.patch_size[1] - W % self.patch_size[1]))
|
|
# if H % self.patch_size[0] != 0:
|
|
# x = F.pad(x, (0, 0, 0, self.patch_size[0] - H % self.patch_size[0]))
|
|
#
|
|
# x = self.proj(x) # B C Wh Ww
|
|
# if self.norm is not None:
|
|
# Wh, Ww = x.size(2), x.size(3)
|
|
# x = x.flatten(2).transpose(1, 2)
|
|
# x = self.norm(x)
|
|
# x = x.transpose(1, 2).view(-1, self.embed_dim, Wh, Ww)
|
|
#
|
|
# return x
|
|
|
|
|
|
class ConvEmbed(nn.Module):
|
|
""" Image to Patch Embedding
|
|
"""
|
|
|
|
def __init__(
|
|
self,
|
|
patch_size=7,
|
|
in_chans=3,
|
|
embed_dim=64,
|
|
stride=4,
|
|
padding=2,
|
|
norm_layer=None
|
|
):
|
|
super().__init__()
|
|
self.patch_size = patch_size
|
|
self.embed_dim = embed_dim
|
|
|
|
self.proj = nn.Conv2d(
|
|
in_chans, embed_dim,
|
|
kernel_size=patch_size,
|
|
stride=stride,
|
|
padding=padding
|
|
)
|
|
self.norm = norm_layer(embed_dim) if norm_layer else None
|
|
|
|
def forward(self, x, H=None, W=None):
|
|
restore_hw = False
|
|
if H is None and W is None and len(x.size()) == 4:
|
|
_, _, H, W = x.size()
|
|
if W % self.patch_size != 0:
|
|
x = F.pad(x, (0, self.patch_size - W % self.patch_size))
|
|
if H % self.patch_size != 0:
|
|
x = F.pad(x, (0, 0, 0, self.patch_size - H % self.patch_size))
|
|
restore_hw = True
|
|
|
|
if len(x.size()) == 3:
|
|
x = rearrange(
|
|
x, 'b (h w) c -> b c h w',
|
|
h=H,
|
|
w=W
|
|
)
|
|
x = self.proj(x) # B C Wh Ww
|
|
B, C, Wh, Ww = x.shape
|
|
x = rearrange(x, 'b c h w -> b (h w) c')
|
|
if self.norm:
|
|
x = self.norm(x)
|
|
|
|
if restore_hw:
|
|
x = rearrange(
|
|
x, 'b (h w) c -> b c h w',
|
|
h=Wh,
|
|
w=Ww
|
|
)
|
|
|
|
return x
|
|
|
|
|
|
class SwinTransformer(nn.Module):
|
|
""" Swin Transformer backbone.
|
|
A PyTorch impl of : `Swin Transformer: Hierarchical Vision Transformer using Shifted Windows` -
|
|
https://arxiv.org/pdf/2103.14030
|
|
Args:
|
|
pretrain_img_size (int): Input image size for training the pretrained model,
|
|
used in absolute postion embedding. Default 224.
|
|
patch_size (int | tuple(int)): Patch size. Default: 4.
|
|
in_chans (int): Number of input image channels. Default: 3.
|
|
embed_dim (int): Number of linear projection output channels. Default: 96.
|
|
depths (tuple[int]): Depths of each Swin Transformer stage.
|
|
num_heads (tuple[int]): Number of attention head of each stage.
|
|
window_size (int): Window size. Default: 7.
|
|
mlp_ratio (float): Ratio of mlp hidden dim to embedding dim. Default: 4.
|
|
qkv_bias (bool): If True, add a learnable bias to query, key, value. Default: True
|
|
qk_scale (float): Override default qk scale of head_dim ** -0.5 if set.
|
|
drop_rate (float): Dropout rate.
|
|
attn_drop_rate (float): Attention dropout rate. Default: 0.
|
|
drop_path_rate (float): Stochastic depth rate. Default: 0.2.
|
|
norm_layer (nn.Module): Normalization layer. Default: nn.LayerNorm.
|
|
ape (bool): If True, add absolute position embedding to the patch embedding. Default: False.
|
|
patch_norm (bool): If True, add normalization after patch embedding. Default: True.
|
|
out_indices (Sequence[int]): Output from which stages.
|
|
frozen_stages (int): Stages to be frozen (stop grad and set eval mode).
|
|
-1 means not freezing any parameters.
|
|
use_checkpoint (bool): Whether to use checkpointing to save memory. Default: False.
|
|
"""
|
|
|
|
def __init__(self,
|
|
pretrain_img_size=224,
|
|
patch_size=7,
|
|
patch_padding=2,
|
|
patch_stride=4,
|
|
in_chans=3,
|
|
embed_dim=96,
|
|
depths=[2, 2, 6, 2],
|
|
num_heads=[3, 6, 12, 24],
|
|
window_size=7,
|
|
mlp_ratio=4.,
|
|
qkv_bias=True,
|
|
qk_scale=None,
|
|
drop_rate=0.,
|
|
attn_drop_rate=0.,
|
|
drop_path_rate=0.2,
|
|
norm_layer=nn.LayerNorm,
|
|
ape=False,
|
|
patch_norm=True,
|
|
frozen_stages=-1,
|
|
use_checkpoint=False,
|
|
layer_scale=False,
|
|
out_features=["stage2", "stage3", "stage4", "stage5"],
|
|
out_norm=True,
|
|
backbone_arch="SWINT-FPN-RETINANET",
|
|
max_query_len=None,
|
|
lang_dim=None):
|
|
super(SwinTransformer, self).__init__()
|
|
|
|
print("VISION BACKBONE USE GRADIENT CHECKPOINTING: ", use_checkpoint)
|
|
|
|
self.pretrain_img_size = pretrain_img_size
|
|
self.num_layers = len(depths)
|
|
self.embed_dim = embed_dim
|
|
self.ape = ape
|
|
self.patch_norm = patch_norm
|
|
self.frozen_stages = frozen_stages
|
|
|
|
self.out_features = out_features
|
|
self.out_norm = out_norm
|
|
|
|
# split image into non-overlapping patches
|
|
# self.patch_embed = PatchEmbed(
|
|
# patch_size=patch_size, in_chans=in_chans, embed_dim=embed_dim,
|
|
# norm_layer=norm_layer if self.patch_norm else None)
|
|
self.patch_embed = ConvEmbed(
|
|
patch_size=patch_size, in_chans=in_chans, embed_dim=embed_dim, padding=patch_padding,
|
|
norm_layer=norm_layer if self.patch_norm else None
|
|
)
|
|
|
|
# absolute position embedding
|
|
if self.ape:
|
|
pretrain_img_size = to_2tuple(pretrain_img_size)
|
|
patch_size = to_2tuple(patch_size)
|
|
patches_resolution = [pretrain_img_size[0] // patch_size[0], pretrain_img_size[1] // patch_size[1]]
|
|
|
|
self.absolute_pos_embed = nn.Parameter(
|
|
torch.zeros(1, embed_dim, patches_resolution[0], patches_resolution[1]))
|
|
trunc_normal_(self.absolute_pos_embed, std=.02)
|
|
|
|
self.pos_drop = nn.Dropout(p=drop_rate)
|
|
|
|
# stochastic depth
|
|
dpr = [x.item() for x in torch.linspace(0, drop_path_rate, sum(depths))] # stochastic depth decay rule
|
|
|
|
self._out_feature_strides = {}
|
|
self._out_feature_channels = {}
|
|
|
|
# build layers
|
|
self.layers = nn.ModuleList()
|
|
for i_layer in range(self.num_layers):
|
|
if i_layer < self.num_layers - 1:
|
|
ntext, dim_text = None, None
|
|
else:
|
|
ntext, dim_text = max_query_len, lang_dim
|
|
layer = BasicLayer(
|
|
dim=int(embed_dim * 2 ** i_layer),
|
|
depth=depths[i_layer],
|
|
num_heads=num_heads[i_layer],
|
|
window_size=window_size,
|
|
mlp_ratio=mlp_ratio,
|
|
qkv_bias=qkv_bias,
|
|
qk_scale=qk_scale,
|
|
drop=drop_rate,
|
|
attn_drop=attn_drop_rate,
|
|
drop_path=dpr[sum(depths[:i_layer]):sum(depths[:i_layer + 1])],
|
|
norm_layer=norm_layer,
|
|
downsample=ConvEmbed if (i_layer < self.num_layers - 1) else None,
|
|
use_checkpoint=use_checkpoint and i_layer > self.frozen_stages - 1,
|
|
layer_scale=layer_scale,
|
|
ntext=ntext,
|
|
dim_text=dim_text
|
|
)
|
|
self.layers.append(layer)
|
|
|
|
stage = f'stage{i_layer + 2}'
|
|
if stage in self.out_features:
|
|
self._out_feature_channels[stage] = embed_dim * 2 ** i_layer
|
|
self._out_feature_strides[stage] = 4 * 2 ** i_layer
|
|
|
|
num_features = [int(embed_dim * 2 ** i) for i in range(self.num_layers)]
|
|
self.num_features = num_features
|
|
|
|
# add a norm layer for each output
|
|
if self.out_norm:
|
|
for i_layer in range(self.num_layers):
|
|
stage = f'stage{i_layer + 2}'
|
|
if stage in self.out_features:
|
|
if i_layer == 0 and backbone_arch.endswith("RETINANET"):
|
|
layer = nn.Identity()
|
|
else:
|
|
layer = norm_layer(num_features[i_layer])
|
|
layer_name = f'norm{i_layer}'
|
|
self.add_module(layer_name, layer)
|
|
|
|
self._freeze_stages()
|
|
|
|
def _freeze_stages(self):
|
|
if self.frozen_stages >= 0:
|
|
self.patch_embed.eval()
|
|
for param in self.patch_embed.parameters():
|
|
param.requires_grad = False
|
|
|
|
if self.frozen_stages >= 1 and self.ape:
|
|
self.absolute_pos_embed.requires_grad = False
|
|
|
|
if self.frozen_stages >= 2:
|
|
self.pos_drop.eval()
|
|
for i in range(0, self.frozen_stages - 1):
|
|
m = self.layers[i]
|
|
m.eval()
|
|
for param in m.parameters():
|
|
param.requires_grad = False
|
|
|
|
def init_weights(self, pretrained=None):
|
|
"""Initialize the weights in backbone.
|
|
Args:
|
|
pretrained (str, optional): Path to pre-trained weights.
|
|
Defaults to None.
|
|
"""
|
|
|
|
def _init_weights(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)
|
|
|
|
self.apply(_init_weights)
|
|
|
|
def forward(self, inputs):
|
|
"""Forward function."""
|
|
x = inputs["img"]
|
|
language_dict_features = inputs["lang"]
|
|
|
|
x = self.patch_embed(x)
|
|
|
|
Wh, Ww = x.size(2), x.size(3)
|
|
if self.ape:
|
|
# interpolate the position embedding to the corresponding size
|
|
absolute_pos_embed = F.interpolate(self.absolute_pos_embed, size=(Wh, Ww), mode='bicubic')
|
|
x = (x + absolute_pos_embed).flatten(2).transpose(1, 2) # B Wh*Ww C
|
|
else:
|
|
x = x.flatten(2).transpose(1, 2)
|
|
x = self.pos_drop(x)
|
|
|
|
x_text = language_dict_features['hidden']
|
|
if "masks" in language_dict_features:
|
|
mask_text = 1.0 - language_dict_features["masks"] # (B, N_text) 0 means not to be masked out
|
|
mask_text.masked_fill_(mask_text.bool(), -float('inf'))
|
|
else:
|
|
mask_text = None
|
|
|
|
outs = []
|
|
for i in range(self.num_layers):
|
|
layer = self.layers[i]
|
|
if i < self.num_layers - 1:
|
|
x_out, H, W, x, Wh, Ww, _ = layer(x, Wh, Ww, x_text=None, mask_text=None)
|
|
else:
|
|
x_out, H, W, x, Wh, Ww, x_text = layer(x, Wh, Ww, x_text=x_text, mask_text=mask_text)
|
|
name = f'stage{i + 2}'
|
|
if name in self.out_features:
|
|
if self.out_norm:
|
|
norm_layer = getattr(self, f'norm{i}')
|
|
x_out = norm_layer(x_out)
|
|
out = x_out.view(-1, H, W, self.num_features[i]).permute(0, 3, 1, 2).contiguous()
|
|
outs.append(out)
|
|
|
|
# the backbone only update the "hidden" field, currently
|
|
language_dict_features['hidden'] = x_text
|
|
|
|
return outs, language_dict_features
|
|
|
|
def train(self, mode=True):
|
|
"""Convert the model into training mode while keep layers freezed."""
|
|
super(SwinTransformer, self).train(mode)
|
|
self._freeze_stages()
|
|
|
|
|
|
def build_swint_backbone(cfg):
|
|
"""
|
|
Create a SwinT instance from config.
|
|
|
|
Returns:
|
|
VoVNet: a :class:`VoVNet` instance.
|
|
"""
|
|
return SwinTransformer(
|
|
patch_size=7,
|
|
patch_padding=2,
|
|
patch_stride=4,
|
|
in_chans=3,
|
|
embed_dim=cfg.MODEL.SWINT.EMBED_DIM,
|
|
depths=cfg.MODEL.SWINT.DEPTHS,
|
|
num_heads=cfg.MODEL.SWINT.NUM_HEADS,
|
|
window_size=cfg.MODEL.SWINT.WINDOW_SIZE,
|
|
mlp_ratio=cfg.MODEL.SWINT.MLP_RATIO,
|
|
qkv_bias=True,
|
|
qk_scale=None,
|
|
drop_rate=0.,
|
|
attn_drop_rate=0.,
|
|
drop_path_rate=cfg.MODEL.SWINT.DROP_PATH_RATE,
|
|
norm_layer=nn.LayerNorm,
|
|
ape=cfg.MODEL.SWINT.APE,
|
|
patch_norm=True,
|
|
frozen_stages=cfg.MODEL.BACKBONE.FREEZE_CONV_BODY_AT,
|
|
backbone_arch=cfg.MODEL.BACKBONE.CONV_BODY,
|
|
use_checkpoint=cfg.MODEL.BACKBONE.USE_CHECKPOINT,
|
|
layer_scale=cfg.MODEL.SWINT.LAYER_SCALE,
|
|
out_features=cfg.MODEL.BACKBONE.OUT_FEATURES,
|
|
out_norm=cfg.MODEL.SWINT.OUT_NORM,
|
|
max_query_len=cfg.MODEL.LANGUAGE_BACKBONE.MAX_QUERY_LEN,
|
|
lang_dim=cfg.MODEL.LANGUAGE_BACKBONE.LANG_DIM
|
|
) |