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# Copyright (c) OpenMMLab. All rights reserved. | |
import copy | |
import torch.nn as nn | |
from mmcv.cnn import ConvModule, Scale | |
from mmdet.models.dense_heads.fcos_head import FCOSHead | |
from mmdet.registry import MODELS | |
from mmdet.utils import OptMultiConfig | |
class NASFCOSHead(FCOSHead): | |
"""Anchor-free head used in `NASFCOS <https://arxiv.org/abs/1906.04423>`_. | |
It is quite similar with FCOS head, except for the searched structure of | |
classification branch and bbox regression branch, where a structure of | |
"dconv3x3, conv3x3, dconv3x3, conv1x1" is utilized instead. | |
Args: | |
num_classes (int): Number of categories excluding the background | |
category. | |
in_channels (int): Number of channels in the input feature map. | |
strides (Sequence[int] or Sequence[Tuple[int, int]]): Strides of points | |
in multiple feature levels. Defaults to (4, 8, 16, 32, 64). | |
regress_ranges (Sequence[Tuple[int, int]]): Regress range of multiple | |
level points. | |
center_sampling (bool): If true, use center sampling. | |
Defaults to False. | |
center_sample_radius (float): Radius of center sampling. | |
Defaults to 1.5. | |
norm_on_bbox (bool): If true, normalize the regression targets with | |
FPN strides. Defaults to False. | |
centerness_on_reg (bool): If true, position centerness on the | |
regress branch. Please refer to https://github.com/tianzhi0549/FCOS/issues/89#issuecomment-516877042. | |
Defaults to False. | |
conv_bias (bool or str): If specified as `auto`, it will be decided by | |
the norm_cfg. Bias of conv will be set as True if `norm_cfg` is | |
None, otherwise False. Defaults to "auto". | |
loss_cls (:obj:`ConfigDict` or dict): Config of classification loss. | |
loss_bbox (:obj:`ConfigDict` or dict): Config of localization loss. | |
loss_centerness (:obj:`ConfigDict`, or dict): Config of centerness | |
loss. | |
norm_cfg (:obj:`ConfigDict` or dict): dictionary to construct and | |
config norm layer. Defaults to | |
``norm_cfg=dict(type='GN', num_groups=32, requires_grad=True)``. | |
init_cfg (:obj:`ConfigDict` or dict or list[:obj:`ConfigDict` or \ | |
dict], opitonal): Initialization config dict. | |
""" # noqa: E501 | |
def __init__(self, | |
*args, | |
init_cfg: OptMultiConfig = None, | |
**kwargs) -> None: | |
if init_cfg is None: | |
init_cfg = [ | |
dict(type='Caffe2Xavier', layer=['ConvModule', 'Conv2d']), | |
dict( | |
type='Normal', | |
std=0.01, | |
override=[ | |
dict(name='conv_reg'), | |
dict(name='conv_centerness'), | |
dict( | |
name='conv_cls', | |
type='Normal', | |
std=0.01, | |
bias_prob=0.01) | |
]), | |
] | |
super().__init__(*args, init_cfg=init_cfg, **kwargs) | |
def _init_layers(self) -> None: | |
"""Initialize layers of the head.""" | |
dconv3x3_config = dict( | |
type='DCNv2', | |
kernel_size=3, | |
use_bias=True, | |
deform_groups=2, | |
padding=1) | |
conv3x3_config = dict(type='Conv', kernel_size=3, padding=1) | |
conv1x1_config = dict(type='Conv', kernel_size=1) | |
self.arch_config = [ | |
dconv3x3_config, conv3x3_config, dconv3x3_config, conv1x1_config | |
] | |
self.cls_convs = nn.ModuleList() | |
self.reg_convs = nn.ModuleList() | |
for i, op_ in enumerate(self.arch_config): | |
op = copy.deepcopy(op_) | |
chn = self.in_channels if i == 0 else self.feat_channels | |
assert isinstance(op, dict) | |
use_bias = op.pop('use_bias', False) | |
padding = op.pop('padding', 0) | |
kernel_size = op.pop('kernel_size') | |
module = ConvModule( | |
chn, | |
self.feat_channels, | |
kernel_size, | |
stride=1, | |
padding=padding, | |
norm_cfg=self.norm_cfg, | |
bias=use_bias, | |
conv_cfg=op) | |
self.cls_convs.append(copy.deepcopy(module)) | |
self.reg_convs.append(copy.deepcopy(module)) | |
self.conv_cls = nn.Conv2d( | |
self.feat_channels, self.cls_out_channels, 3, padding=1) | |
self.conv_reg = nn.Conv2d(self.feat_channels, 4, 3, padding=1) | |
self.conv_centerness = nn.Conv2d(self.feat_channels, 1, 3, padding=1) | |
self.scales = nn.ModuleList([Scale(1.0) for _ in self.strides]) | |