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# Copyright (c) OpenMMLab. All rights reserved. | |
from typing import List, Optional, Tuple, Union | |
import torch.nn as nn | |
from mmcv.cnn import ConvModule | |
from mmdet.models.backbones.csp_darknet import Focus | |
from mmdet.utils import ConfigType, OptMultiConfig | |
from mmyolo.registry import MODELS | |
from ..layers import MaxPoolAndStrideConvBlock | |
from .base_backbone import BaseBackbone | |
class YOLOv7Backbone(BaseBackbone): | |
"""Backbone used in YOLOv7. | |
Args: | |
arch (str): Architecture of YOLOv7Defaults to L. | |
deepen_factor (float): Depth multiplier, multiply number of | |
blocks in CSP layer by this amount. Defaults to 1.0. | |
widen_factor (float): Width multiplier, multiply number of | |
channels in each layer by this amount. Defaults to 1.0. | |
out_indices (Sequence[int]): Output from which stages. | |
Defaults to (2, 3, 4). | |
frozen_stages (int): Stages to be frozen (stop grad and set eval | |
mode). -1 means not freezing any parameters. Defaults to -1. | |
plugins (list[dict]): List of plugins for stages, each dict contains: | |
- cfg (dict, required): Cfg dict to build plugin. | |
- stages (tuple[bool], optional): Stages to apply plugin, length | |
should be same as 'num_stages'. | |
norm_cfg (:obj:`ConfigDict` or dict): Dictionary to construct and | |
config norm layer. Defaults to dict(type='BN', requires_grad=True). | |
act_cfg (:obj:`ConfigDict` or dict): Config dict for activation layer. | |
Defaults to dict(type='SiLU', inplace=True). | |
norm_eval (bool): Whether to set norm layers to eval mode, namely, | |
freeze running stats (mean and var). Note: Effect on Batch Norm | |
and its variants only. | |
init_cfg (:obj:`ConfigDict` or dict or list[dict] or | |
list[:obj:`ConfigDict`]): Initialization config dict. | |
""" | |
_tiny_stage1_cfg = dict(type='TinyDownSampleBlock', middle_ratio=0.5) | |
_tiny_stage2_4_cfg = dict(type='TinyDownSampleBlock', middle_ratio=1.0) | |
_l_expand_channel_2x = dict( | |
type='ELANBlock', | |
middle_ratio=0.5, | |
block_ratio=0.5, | |
num_blocks=2, | |
num_convs_in_block=2) | |
_l_no_change_channel = dict( | |
type='ELANBlock', | |
middle_ratio=0.25, | |
block_ratio=0.25, | |
num_blocks=2, | |
num_convs_in_block=2) | |
_x_expand_channel_2x = dict( | |
type='ELANBlock', | |
middle_ratio=0.4, | |
block_ratio=0.4, | |
num_blocks=3, | |
num_convs_in_block=2) | |
_x_no_change_channel = dict( | |
type='ELANBlock', | |
middle_ratio=0.2, | |
block_ratio=0.2, | |
num_blocks=3, | |
num_convs_in_block=2) | |
_w_no_change_channel = dict( | |
type='ELANBlock', | |
middle_ratio=0.5, | |
block_ratio=0.5, | |
num_blocks=2, | |
num_convs_in_block=2) | |
_e_no_change_channel = dict( | |
type='ELANBlock', | |
middle_ratio=0.4, | |
block_ratio=0.4, | |
num_blocks=3, | |
num_convs_in_block=2) | |
_d_no_change_channel = dict( | |
type='ELANBlock', | |
middle_ratio=1 / 3, | |
block_ratio=1 / 3, | |
num_blocks=4, | |
num_convs_in_block=2) | |
_e2e_no_change_channel = dict( | |
type='EELANBlock', | |
num_elan_block=2, | |
middle_ratio=0.4, | |
block_ratio=0.4, | |
num_blocks=3, | |
num_convs_in_block=2) | |
# From left to right: | |
# in_channels, out_channels, Block_params | |
arch_settings = { | |
'Tiny': [[64, 64, _tiny_stage1_cfg], [64, 128, _tiny_stage2_4_cfg], | |
[128, 256, _tiny_stage2_4_cfg], | |
[256, 512, _tiny_stage2_4_cfg]], | |
'L': [[64, 256, _l_expand_channel_2x], | |
[256, 512, _l_expand_channel_2x], | |
[512, 1024, _l_expand_channel_2x], | |
[1024, 1024, _l_no_change_channel]], | |
'X': [[80, 320, _x_expand_channel_2x], | |
[320, 640, _x_expand_channel_2x], | |
[640, 1280, _x_expand_channel_2x], | |
[1280, 1280, _x_no_change_channel]], | |
'W': | |
[[64, 128, _w_no_change_channel], [128, 256, _w_no_change_channel], | |
[256, 512, _w_no_change_channel], [512, 768, _w_no_change_channel], | |
[768, 1024, _w_no_change_channel]], | |
'E': | |
[[80, 160, _e_no_change_channel], [160, 320, _e_no_change_channel], | |
[320, 640, _e_no_change_channel], [640, 960, _e_no_change_channel], | |
[960, 1280, _e_no_change_channel]], | |
'D': [[96, 192, | |
_d_no_change_channel], [192, 384, _d_no_change_channel], | |
[384, 768, _d_no_change_channel], | |
[768, 1152, _d_no_change_channel], | |
[1152, 1536, _d_no_change_channel]], | |
'E2E': [[80, 160, _e2e_no_change_channel], | |
[160, 320, _e2e_no_change_channel], | |
[320, 640, _e2e_no_change_channel], | |
[640, 960, _e2e_no_change_channel], | |
[960, 1280, _e2e_no_change_channel]], | |
} | |
def __init__(self, | |
arch: str = 'L', | |
deepen_factor: float = 1.0, | |
widen_factor: float = 1.0, | |
input_channels: int = 3, | |
out_indices: Tuple[int] = (2, 3, 4), | |
frozen_stages: int = -1, | |
plugins: Union[dict, List[dict]] = None, | |
norm_cfg: ConfigType = dict( | |
type='BN', momentum=0.03, eps=0.001), | |
act_cfg: ConfigType = dict(type='SiLU', inplace=True), | |
norm_eval: bool = False, | |
init_cfg: OptMultiConfig = None): | |
assert arch in self.arch_settings.keys() | |
self.arch = arch | |
super().__init__( | |
self.arch_settings[arch], | |
deepen_factor, | |
widen_factor, | |
input_channels=input_channels, | |
out_indices=out_indices, | |
plugins=plugins, | |
frozen_stages=frozen_stages, | |
norm_cfg=norm_cfg, | |
act_cfg=act_cfg, | |
norm_eval=norm_eval, | |
init_cfg=init_cfg) | |
def build_stem_layer(self) -> nn.Module: | |
"""Build a stem layer.""" | |
if self.arch in ['L', 'X']: | |
stem = nn.Sequential( | |
ConvModule( | |
3, | |
int(self.arch_setting[0][0] * self.widen_factor // 2), | |
3, | |
padding=1, | |
stride=1, | |
norm_cfg=self.norm_cfg, | |
act_cfg=self.act_cfg), | |
ConvModule( | |
int(self.arch_setting[0][0] * self.widen_factor // 2), | |
int(self.arch_setting[0][0] * self.widen_factor), | |
3, | |
padding=1, | |
stride=2, | |
norm_cfg=self.norm_cfg, | |
act_cfg=self.act_cfg), | |
ConvModule( | |
int(self.arch_setting[0][0] * self.widen_factor), | |
int(self.arch_setting[0][0] * self.widen_factor), | |
3, | |
padding=1, | |
stride=1, | |
norm_cfg=self.norm_cfg, | |
act_cfg=self.act_cfg)) | |
elif self.arch == 'Tiny': | |
stem = nn.Sequential( | |
ConvModule( | |
3, | |
int(self.arch_setting[0][0] * self.widen_factor // 2), | |
3, | |
padding=1, | |
stride=2, | |
norm_cfg=self.norm_cfg, | |
act_cfg=self.act_cfg), | |
ConvModule( | |
int(self.arch_setting[0][0] * self.widen_factor // 2), | |
int(self.arch_setting[0][0] * self.widen_factor), | |
3, | |
padding=1, | |
stride=2, | |
norm_cfg=self.norm_cfg, | |
act_cfg=self.act_cfg)) | |
elif self.arch in ['W', 'E', 'D', 'E2E']: | |
stem = Focus( | |
3, | |
int(self.arch_setting[0][0] * self.widen_factor), | |
kernel_size=3, | |
norm_cfg=self.norm_cfg, | |
act_cfg=self.act_cfg) | |
return stem | |
def build_stage_layer(self, stage_idx: int, setting: list) -> list: | |
"""Build a stage layer. | |
Args: | |
stage_idx (int): The index of a stage layer. | |
setting (list): The architecture setting of a stage layer. | |
""" | |
in_channels, out_channels, stage_block_cfg = setting | |
in_channels = int(in_channels * self.widen_factor) | |
out_channels = int(out_channels * self.widen_factor) | |
stage_block_cfg = stage_block_cfg.copy() | |
stage_block_cfg.setdefault('norm_cfg', self.norm_cfg) | |
stage_block_cfg.setdefault('act_cfg', self.act_cfg) | |
stage_block_cfg['in_channels'] = in_channels | |
stage_block_cfg['out_channels'] = out_channels | |
stage = [] | |
if self.arch in ['W', 'E', 'D', 'E2E']: | |
stage_block_cfg['in_channels'] = out_channels | |
elif self.arch in ['L', 'X']: | |
if stage_idx == 0: | |
stage_block_cfg['in_channels'] = out_channels // 2 | |
downsample_layer = self._build_downsample_layer( | |
stage_idx, in_channels, out_channels) | |
stage.append(MODELS.build(stage_block_cfg)) | |
if downsample_layer is not None: | |
stage.insert(0, downsample_layer) | |
return stage | |
def _build_downsample_layer(self, stage_idx: int, in_channels: int, | |
out_channels: int) -> Optional[nn.Module]: | |
"""Build a downsample layer pre stage.""" | |
if self.arch in ['E', 'D', 'E2E']: | |
downsample_layer = MaxPoolAndStrideConvBlock( | |
in_channels, | |
out_channels, | |
use_in_channels_of_middle=True, | |
norm_cfg=self.norm_cfg, | |
act_cfg=self.act_cfg) | |
elif self.arch == 'W': | |
downsample_layer = ConvModule( | |
in_channels, | |
out_channels, | |
3, | |
stride=2, | |
padding=1, | |
norm_cfg=self.norm_cfg, | |
act_cfg=self.act_cfg) | |
elif self.arch == 'Tiny': | |
if stage_idx != 0: | |
downsample_layer = nn.MaxPool2d(2, 2) | |
else: | |
downsample_layer = None | |
elif self.arch in ['L', 'X']: | |
if stage_idx == 0: | |
downsample_layer = ConvModule( | |
in_channels, | |
out_channels // 2, | |
3, | |
stride=2, | |
padding=1, | |
norm_cfg=self.norm_cfg, | |
act_cfg=self.act_cfg) | |
else: | |
downsample_layer = MaxPoolAndStrideConvBlock( | |
in_channels, | |
in_channels, | |
use_in_channels_of_middle=False, | |
norm_cfg=self.norm_cfg, | |
act_cfg=self.act_cfg) | |
return downsample_layer | |