MaureenZOU
init
e972e1f
# --------------------------------------------------------
# FocalNet for Semantic Segmentation
# Copyright (c) 2022 Microsoft
# Licensed under The MIT License [see LICENSE for details]
# Written by Jianwei Yang
# --------------------------------------------------------
import math
import time
import numpy as np
import logging
import torch
import torch.nn as nn
import torch.nn.functional as F
import torch.utils.checkpoint as checkpoint
from timm.models.layers import DropPath, to_2tuple, trunc_normal_
from detectron2.utils.file_io import PathManager
from detectron2.modeling import BACKBONE_REGISTRY, Backbone, ShapeSpec
from .registry import register_backbone
logger = logging.getLogger(__name__)
class Mlp(nn.Module):
""" Multilayer perceptron."""
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.act = act_layer()
self.fc2 = nn.Linear(hidden_features, out_features)
self.drop = nn.Dropout(drop)
def forward(self, x):
x = self.fc1(x)
x = self.act(x)
x = self.drop(x)
x = self.fc2(x)
x = self.drop(x)
return x
class FocalModulation(nn.Module):
""" Focal Modulation
Args:
dim (int): Number of input channels.
proj_drop (float, optional): Dropout ratio of output. Default: 0.0
focal_level (int): Number of focal levels
focal_window (int): Focal window size at focal level 1
focal_factor (int, default=2): Step to increase the focal window
use_postln (bool, default=False): Whether use post-modulation layernorm
"""
def __init__(self, dim, proj_drop=0., focal_level=2, focal_window=7, focal_factor=2, use_postln=False, use_postln_in_modulation=False, scaling_modulator=False):
super().__init__()
self.dim = dim
# specific args for focalv3
self.focal_level = focal_level
self.focal_window = focal_window
self.focal_factor = focal_factor
self.use_postln_in_modulation = use_postln_in_modulation
self.scaling_modulator = scaling_modulator
self.f = nn.Linear(dim, 2*dim+(self.focal_level+1), bias=True)
self.h = nn.Conv2d(dim, dim, kernel_size=1, stride=1, padding=0, groups=1, bias=True)
self.act = nn.GELU()
self.proj = nn.Linear(dim, dim)
self.proj_drop = nn.Dropout(proj_drop)
self.focal_layers = nn.ModuleList()
if self.use_postln_in_modulation:
self.ln = nn.LayerNorm(dim)
for k in range(self.focal_level):
kernel_size = self.focal_factor*k + self.focal_window
self.focal_layers.append(
nn.Sequential(
nn.Conv2d(dim, dim, kernel_size=kernel_size, stride=1, groups=dim,
padding=kernel_size//2, bias=False),
nn.GELU(),
)
)
def forward(self, x):
""" Forward function.
Args:
x: input features with shape of (B, H, W, C)
"""
B, nH, nW, C = x.shape
x = self.f(x)
x = x.permute(0, 3, 1, 2).contiguous()
q, ctx, gates = torch.split(x, (C, C, self.focal_level+1), 1)
ctx_all = 0
for l in range(self.focal_level):
ctx = self.focal_layers[l](ctx)
ctx_all = ctx_all + ctx*gates[:, l:l+1]
ctx_global = self.act(ctx.mean(2, keepdim=True).mean(3, keepdim=True))
ctx_all = ctx_all + ctx_global*gates[:,self.focal_level:]
if self.scaling_modulator:
ctx_all = ctx_all / (self.focal_level + 1)
x_out = q * self.h(ctx_all)
x_out = x_out.permute(0, 2, 3, 1).contiguous()
if self.use_postln_in_modulation:
x_out = self.ln(x_out)
x_out = self.proj(x_out)
x_out = self.proj_drop(x_out)
return x_out
class FocalModulationBlock(nn.Module):
""" Focal Modulation Block.
Args:
dim (int): Number of input channels.
mlp_ratio (float): Ratio of mlp hidden dim to embedding dim.
drop (float, optional): Dropout rate. Default: 0.0
drop_path (float, optional): Stochastic depth rate. Default: 0.0
act_layer (nn.Module, optional): Activation layer. Default: nn.GELU
norm_layer (nn.Module, optional): Normalization layer. Default: nn.LayerNorm
focal_level (int): number of focal levels
focal_window (int): focal kernel size at level 1
"""
def __init__(self, dim, mlp_ratio=4., drop=0., drop_path=0.,
act_layer=nn.GELU, norm_layer=nn.LayerNorm,
focal_level=2, focal_window=9,
use_postln=False, use_postln_in_modulation=False,
scaling_modulator=False,
use_layerscale=False,
layerscale_value=1e-4):
super().__init__()
self.dim = dim
self.mlp_ratio = mlp_ratio
self.focal_window = focal_window
self.focal_level = focal_level
self.use_postln = use_postln
self.use_layerscale = use_layerscale
self.norm1 = norm_layer(dim)
self.modulation = FocalModulation(
dim, focal_window=self.focal_window, focal_level=self.focal_level, proj_drop=drop, use_postln_in_modulation=use_postln_in_modulation, scaling_modulator=scaling_modulator
)
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.H = None
self.W = None
self.gamma_1 = 1.0
self.gamma_2 = 1.0
if self.use_layerscale:
self.gamma_1 = nn.Parameter(layerscale_value * torch.ones((dim)), requires_grad=True)
self.gamma_2 = nn.Parameter(layerscale_value * torch.ones((dim)), requires_grad=True)
def forward(self, x):
""" Forward function.
Args:
x: Input feature, tensor size (B, H*W, C).
H, W: Spatial resolution of the input feature.
"""
B, L, C = x.shape
H, W = self.H, self.W
assert L == H * W, "input feature has wrong size"
shortcut = x
if not self.use_postln:
x = self.norm1(x)
x = x.view(B, H, W, C)
# FM
x = self.modulation(x).view(B, H * W, C)
if self.use_postln:
x = self.norm1(x)
# FFN
x = shortcut + self.drop_path(self.gamma_1 * x)
if self.use_postln:
x = x + self.drop_path(self.gamma_2 * self.norm2(self.mlp(x)))
else:
x = x + self.drop_path(self.gamma_2 * self.mlp(self.norm2(x)))
return x
class BasicLayer(nn.Module):
""" A basic focal modulation layer for one stage.
Args:
dim (int): Number of feature channels
depth (int): Depths of this stage.
mlp_ratio (float): Ratio of mlp hidden dim to embedding dim. Default: 4.
drop (float, optional): 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
focal_level (int): Number of focal levels
focal_window (int): Focal window size at focal level 1
use_conv_embed (bool): Use overlapped convolution for patch embedding or now. Default: False
use_checkpoint (bool): Whether to use checkpointing to save memory. Default: False
"""
def __init__(self,
dim,
depth,
mlp_ratio=4.,
drop=0.,
drop_path=0.,
norm_layer=nn.LayerNorm,
downsample=None,
focal_window=9,
focal_level=2,
use_conv_embed=False,
use_postln=False,
use_postln_in_modulation=False,
scaling_modulator=False,
use_layerscale=False,
use_checkpoint=False
):
super().__init__()
self.depth = depth
self.use_checkpoint = use_checkpoint
# build blocks
self.blocks = nn.ModuleList([
FocalModulationBlock(
dim=dim,
mlp_ratio=mlp_ratio,
drop=drop,
drop_path=drop_path[i] if isinstance(drop_path, list) else drop_path,
focal_window=focal_window,
focal_level=focal_level,
use_postln=use_postln,
use_postln_in_modulation=use_postln_in_modulation,
scaling_modulator=scaling_modulator,
use_layerscale=use_layerscale,
norm_layer=norm_layer)
for i in range(depth)])
# patch merging layer
if downsample is not None:
self.downsample = downsample(
patch_size=2,
in_chans=dim, embed_dim=2*dim,
use_conv_embed=use_conv_embed,
norm_layer=norm_layer,
is_stem=False
)
else:
self.downsample = None
def forward(self, x, H, W):
""" Forward function.
Args:
x: Input feature, tensor size (B, H*W, C).
H, W: Spatial resolution of the input feature.
"""
for blk in self.blocks:
blk.H, blk.W = H, W
if self.use_checkpoint:
x = checkpoint.checkpoint(blk, x)
else:
x = blk(x)
if self.downsample is not None:
x_reshaped = x.transpose(1, 2).view(x.shape[0], x.shape[-1], H, W)
x_down = self.downsample(x_reshaped)
x_down = x_down.flatten(2).transpose(1, 2)
Wh, Ww = (H + 1) // 2, (W + 1) // 2
return x, H, W, x_down, Wh, Ww
else:
return x, H, W, x, H, W
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
use_conv_embed (bool): Whether use overlapped convolution for patch embedding. Default: False
is_stem (bool): Is the stem block or not.
"""
def __init__(self, patch_size=4, in_chans=3, embed_dim=96, norm_layer=None, use_conv_embed=False, is_stem=False):
super().__init__()
patch_size = to_2tuple(patch_size)
self.patch_size = patch_size
self.in_chans = in_chans
self.embed_dim = embed_dim
if use_conv_embed:
# if we choose to use conv embedding, then we treat the stem and non-stem differently
if is_stem:
kernel_size = 7; padding = 2; stride = 4
else:
kernel_size = 3; padding = 1; stride = 2
self.proj = nn.Conv2d(in_chans, embed_dim, kernel_size=kernel_size, stride=stride, padding=padding)
else:
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."""
_, _, 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 FocalNet(nn.Module):
""" FocalNet backbone.
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.
mlp_ratio (float): Ratio of mlp hidden dim to embedding dim. Default: 4.
drop_rate (float): Dropout rate.
drop_path_rate (float): Stochastic depth rate. Default: 0.2.
norm_layer (nn.Module): Normalization layer. Default: nn.LayerNorm.
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.
focal_levels (Sequence[int]): Number of focal levels at four stages
focal_windows (Sequence[int]): Focal window sizes at first focal level at four stages
use_conv_embed (bool): Whether use overlapped convolution for patch embedding
use_checkpoint (bool): Whether to use checkpointing to save memory. Default: False.
"""
def __init__(self,
pretrain_img_size=1600,
patch_size=4,
in_chans=3,
embed_dim=96,
depths=[2, 2, 6, 2],
mlp_ratio=4.,
drop_rate=0.,
drop_path_rate=0.2,
norm_layer=nn.LayerNorm,
patch_norm=True,
out_indices=[0, 1, 2, 3],
frozen_stages=-1,
focal_levels=[2,2,2,2],
focal_windows=[9,9,9,9],
use_conv_embed=False,
use_postln=False,
use_postln_in_modulation=False,
scaling_modulator=False,
use_layerscale=False,
use_checkpoint=False,
):
super().__init__()
self.pretrain_img_size = pretrain_img_size
self.num_layers = len(depths)
self.embed_dim = embed_dim
self.patch_norm = patch_norm
self.out_indices = out_indices
self.frozen_stages = frozen_stages
# 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,
use_conv_embed=use_conv_embed, is_stem=True)
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
# build layers
self.layers = nn.ModuleList()
for i_layer in range(self.num_layers):
layer = BasicLayer(
dim=int(embed_dim * 2 ** i_layer),
depth=depths[i_layer],
mlp_ratio=mlp_ratio,
drop=drop_rate,
drop_path=dpr[sum(depths[:i_layer]):sum(depths[:i_layer + 1])],
norm_layer=norm_layer,
downsample=PatchEmbed if (i_layer < self.num_layers - 1) else None,
focal_window=focal_windows[i_layer],
focal_level=focal_levels[i_layer],
use_conv_embed=use_conv_embed,
use_postln=use_postln,
use_postln_in_modulation=use_postln_in_modulation,
scaling_modulator=scaling_modulator,
use_layerscale=use_layerscale,
use_checkpoint=use_checkpoint)
self.layers.append(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
for i_layer in out_indices:
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 >= 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)
if isinstance(pretrained, str):
self.apply(_init_weights)
logger = get_root_logger()
load_checkpoint(self, pretrained, strict=False, logger=logger)
elif pretrained is None:
self.apply(_init_weights)
else:
raise TypeError('pretrained must be a str or None')
def load_weights(self, pretrained_dict=None, pretrained_layers=[], verbose=True):
model_dict = self.state_dict()
missed_dict = [k for k in model_dict.keys() if k not in pretrained_dict]
logger.info(f'=> Missed keys {missed_dict}')
unexpected_dict = [k for k in pretrained_dict.keys() if k not in model_dict]
logger.info(f'=> Unexpected keys {unexpected_dict}')
pretrained_dict = {
k: v for k, v in pretrained_dict.items()
if k in model_dict.keys()
}
need_init_state_dict = {}
for k, v in pretrained_dict.items():
need_init = (
(
k.split('.')[0] in pretrained_layers
or pretrained_layers[0] == '*'
)
and 'relative_position_index' not in k
and 'attn_mask' not in k
)
if need_init:
# if verbose:
# logger.info(f'=> init {k} from {pretrained}')
if ('pool_layers' in k) or ('focal_layers' in k) and v.size() != model_dict[k].size():
table_pretrained = v
table_current = model_dict[k]
fsize1 = table_pretrained.shape[2]
fsize2 = table_current.shape[2]
# NOTE: different from interpolation used in self-attention, we use padding or clipping for focal conv
if fsize1 < fsize2:
table_pretrained_resized = torch.zeros(table_current.shape)
table_pretrained_resized[:, :, (fsize2-fsize1)//2:-(fsize2-fsize1)//2, (fsize2-fsize1)//2:-(fsize2-fsize1)//2] = table_pretrained
v = table_pretrained_resized
elif fsize1 > fsize2:
table_pretrained_resized = table_pretrained[:, :, (fsize1-fsize2)//2:-(fsize1-fsize2)//2, (fsize1-fsize2)//2:-(fsize1-fsize2)//2]
v = table_pretrained_resized
if ("modulation.f" in k or "pre_conv" in k):
table_pretrained = v
table_current = model_dict[k]
if table_pretrained.shape != table_current.shape:
if len(table_pretrained.shape) == 2:
dim = table_pretrained.shape[1]
assert table_current.shape[1] == dim
L1 = table_pretrained.shape[0]
L2 = table_current.shape[0]
if L1 < L2:
table_pretrained_resized = torch.zeros(table_current.shape)
# copy for linear project
table_pretrained_resized[:2*dim] = table_pretrained[:2*dim]
# copy for global token gating
table_pretrained_resized[-1] = table_pretrained[-1]
# copy for first multiple focal levels
table_pretrained_resized[2*dim:2*dim+(L1-2*dim-1)] = table_pretrained[2*dim:-1]
# reassign pretrained weights
v = table_pretrained_resized
elif L1 > L2:
raise NotImplementedError
elif len(table_pretrained.shape) == 1:
dim = table_pretrained.shape[0]
L1 = table_pretrained.shape[0]
L2 = table_current.shape[0]
if L1 < L2:
table_pretrained_resized = torch.zeros(table_current.shape)
# copy for linear project
table_pretrained_resized[:dim] = table_pretrained[:dim]
# copy for global token gating
table_pretrained_resized[-1] = table_pretrained[-1]
# copy for first multiple focal levels
# table_pretrained_resized[dim:2*dim+(L1-2*dim-1)] = table_pretrained[2*dim:-1]
# reassign pretrained weights
v = table_pretrained_resized
elif L1 > L2:
raise NotImplementedError
need_init_state_dict[k] = v
self.load_state_dict(need_init_state_dict, strict=False)
def forward(self, x):
"""Forward function."""
tic = time.time()
x = self.patch_embed(x)
Wh, Ww = x.size(2), x.size(3)
x = x.flatten(2).transpose(1, 2)
x = self.pos_drop(x)
outs = {}
for i in range(self.num_layers):
layer = self.layers[i]
x_out, H, W, x, Wh, Ww = layer(x, Wh, Ww)
if i in self.out_indices:
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["res{}".format(i + 2)] = out
if len(self.out_indices) == 0:
outs["res5"] = x_out.view(-1, H, W, self.num_features[i]).permute(0, 3, 1, 2).contiguous()
toc = time.time()
return outs
def train(self, mode=True):
"""Convert the model into training mode while keep layers freezed."""
super(FocalNet, self).train(mode)
self._freeze_stages()
class D2FocalNet(FocalNet, Backbone):
def __init__(self, cfg, input_shape):
pretrain_img_size = cfg['BACKBONE']['FOCAL']['PRETRAIN_IMG_SIZE']
patch_size = cfg['BACKBONE']['FOCAL']['PATCH_SIZE']
in_chans = 3
embed_dim = cfg['BACKBONE']['FOCAL']['EMBED_DIM']
depths = cfg['BACKBONE']['FOCAL']['DEPTHS']
mlp_ratio = cfg['BACKBONE']['FOCAL']['MLP_RATIO']
drop_rate = cfg['BACKBONE']['FOCAL']['DROP_RATE']
drop_path_rate = cfg['BACKBONE']['FOCAL']['DROP_PATH_RATE']
norm_layer = nn.LayerNorm
patch_norm = cfg['BACKBONE']['FOCAL']['PATCH_NORM']
use_checkpoint = cfg['BACKBONE']['FOCAL']['USE_CHECKPOINT']
out_indices = cfg['BACKBONE']['FOCAL']['OUT_INDICES']
scaling_modulator = cfg['BACKBONE']['FOCAL'].get('SCALING_MODULATOR', False)
super().__init__(
pretrain_img_size,
patch_size,
in_chans,
embed_dim,
depths,
mlp_ratio,
drop_rate,
drop_path_rate,
norm_layer,
patch_norm,
out_indices,
focal_levels=cfg['BACKBONE']['FOCAL']['FOCAL_LEVELS'],
focal_windows=cfg['BACKBONE']['FOCAL']['FOCAL_WINDOWS'],
use_conv_embed=cfg['BACKBONE']['FOCAL']['USE_CONV_EMBED'],
use_postln=cfg['BACKBONE']['FOCAL']['USE_POSTLN'],
use_postln_in_modulation=cfg['BACKBONE']['FOCAL']['USE_POSTLN_IN_MODULATION'],
scaling_modulator=scaling_modulator,
use_layerscale=cfg['BACKBONE']['FOCAL']['USE_LAYERSCALE'],
use_checkpoint=use_checkpoint,
)
self._out_features = cfg['BACKBONE']['FOCAL']['OUT_FEATURES']
self._out_feature_strides = {
"res2": 4,
"res3": 8,
"res4": 16,
"res5": 32,
}
self._out_feature_channels = {
"res2": self.num_features[0],
"res3": self.num_features[1],
"res4": self.num_features[2],
"res5": self.num_features[3],
}
def forward(self, x):
"""
Args:
x: Tensor of shape (N,C,H,W). H, W must be a multiple of ``self.size_divisibility``.
Returns:
dict[str->Tensor]: names and the corresponding features
"""
assert (
x.dim() == 4
), f"SwinTransformer takes an input of shape (N, C, H, W). Got {x.shape} instead!"
outputs = {}
y = super().forward(x)
for k in y.keys():
if k in self._out_features:
outputs[k] = y[k]
return outputs
def output_shape(self):
return {
name: ShapeSpec(
channels=self._out_feature_channels[name], stride=self._out_feature_strides[name]
)
for name in self._out_features
}
@property
def size_divisibility(self):
return 32
@register_backbone
def get_focal_backbone(cfg):
focal = D2FocalNet(cfg['MODEL'], 224)
if cfg['MODEL']['BACKBONE']['LOAD_PRETRAINED'] is True:
filename = cfg['MODEL']['BACKBONE']['PRETRAINED']
logger.info(f'=> init from {filename}')
with PathManager.open(filename, "rb") as f:
ckpt = torch.load(f)['model']
focal.load_weights(ckpt, cfg['MODEL']['BACKBONE']['FOCAL'].get('PRETRAINED_LAYERS', ['*']), cfg['VERBOSE'])
return focal