Spaces:
Runtime error
Runtime error
File size: 6,703 Bytes
51f6859 |
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 |
# Copyright (c) OpenMMLab. All rights reserved.
import torch.nn as nn
import torch.nn.functional as F
from mmcv.cnn import ConvModule, caffe2_xavier_init
from mmcv.ops.merge_cells import ConcatCell
from mmcv.runner import BaseModule
from ..builder import NECKS
@NECKS.register_module()
class NASFCOS_FPN(BaseModule):
"""FPN structure in NASFPN.
Implementation of paper `NAS-FCOS: Fast Neural Architecture Search for
Object Detection <https://arxiv.org/abs/1906.04423>`_
Args:
in_channels (List[int]): Number of input channels per scale.
out_channels (int): Number of output channels (used at each scale)
num_outs (int): Number of output scales.
start_level (int): Index of the start input backbone level used to
build the feature pyramid. Default: 0.
end_level (int): Index of the end input backbone level (exclusive) to
build the feature pyramid. Default: -1, which means the last level.
add_extra_convs (bool): It decides whether to add conv
layers on top of the original feature maps. Default to False.
If True, its actual mode is specified by `extra_convs_on_inputs`.
conv_cfg (dict): dictionary to construct and config conv layer.
norm_cfg (dict): dictionary to construct and config norm layer.
init_cfg (dict or list[dict], optional): Initialization config dict.
Default: None
"""
def __init__(self,
in_channels,
out_channels,
num_outs,
start_level=1,
end_level=-1,
add_extra_convs=False,
conv_cfg=None,
norm_cfg=None,
init_cfg=None):
assert init_cfg is None, 'To prevent abnormal initialization ' \
'behavior, init_cfg is not allowed to be set'
super(NASFCOS_FPN, self).__init__(init_cfg)
assert isinstance(in_channels, list)
self.in_channels = in_channels
self.out_channels = out_channels
self.num_ins = len(in_channels)
self.num_outs = num_outs
self.norm_cfg = norm_cfg
self.conv_cfg = conv_cfg
if end_level == -1 or end_level == self.num_ins - 1:
self.backbone_end_level = self.num_ins
assert num_outs >= self.num_ins - start_level
else:
# if end_level is not the last level, no extra level is allowed
self.backbone_end_level = end_level + 1
assert end_level < self.num_ins
assert num_outs == end_level - start_level + 1
self.start_level = start_level
self.end_level = end_level
self.add_extra_convs = add_extra_convs
self.adapt_convs = nn.ModuleList()
for i in range(self.start_level, self.backbone_end_level):
adapt_conv = ConvModule(
in_channels[i],
out_channels,
1,
stride=1,
padding=0,
bias=False,
norm_cfg=dict(type='BN'),
act_cfg=dict(type='ReLU', inplace=False))
self.adapt_convs.append(adapt_conv)
# C2 is omitted according to the paper
extra_levels = num_outs - self.backbone_end_level + self.start_level
def build_concat_cell(with_input1_conv, with_input2_conv):
cell_conv_cfg = dict(
kernel_size=1, padding=0, bias=False, groups=out_channels)
return ConcatCell(
in_channels=out_channels,
out_channels=out_channels,
with_out_conv=True,
out_conv_cfg=cell_conv_cfg,
out_norm_cfg=dict(type='BN'),
out_conv_order=('norm', 'act', 'conv'),
with_input1_conv=with_input1_conv,
with_input2_conv=with_input2_conv,
input_conv_cfg=conv_cfg,
input_norm_cfg=norm_cfg,
upsample_mode='nearest')
# Denote c3=f0, c4=f1, c5=f2 for convince
self.fpn = nn.ModuleDict()
self.fpn['c22_1'] = build_concat_cell(True, True)
self.fpn['c22_2'] = build_concat_cell(True, True)
self.fpn['c32'] = build_concat_cell(True, False)
self.fpn['c02'] = build_concat_cell(True, False)
self.fpn['c42'] = build_concat_cell(True, True)
self.fpn['c36'] = build_concat_cell(True, True)
self.fpn['c61'] = build_concat_cell(True, True) # f9
self.extra_downsamples = nn.ModuleList()
for i in range(extra_levels):
extra_act_cfg = None if i == 0 \
else dict(type='ReLU', inplace=False)
self.extra_downsamples.append(
ConvModule(
out_channels,
out_channels,
3,
stride=2,
padding=1,
act_cfg=extra_act_cfg,
order=('act', 'norm', 'conv')))
def forward(self, inputs):
"""Forward function."""
feats = [
adapt_conv(inputs[i + self.start_level])
for i, adapt_conv in enumerate(self.adapt_convs)
]
for (i, module_name) in enumerate(self.fpn):
idx_1, idx_2 = int(module_name[1]), int(module_name[2])
res = self.fpn[module_name](feats[idx_1], feats[idx_2])
feats.append(res)
ret = []
for (idx, input_idx) in zip([9, 8, 7], [1, 2, 3]): # add P3, P4, P5
feats1, feats2 = feats[idx], feats[5]
feats2_resize = F.interpolate(
feats2,
size=feats1.size()[2:],
mode='bilinear',
align_corners=False)
feats_sum = feats1 + feats2_resize
ret.append(
F.interpolate(
feats_sum,
size=inputs[input_idx].size()[2:],
mode='bilinear',
align_corners=False))
for submodule in self.extra_downsamples:
ret.append(submodule(ret[-1]))
return tuple(ret)
def init_weights(self):
"""Initialize the weights of module."""
super(NASFCOS_FPN, self).init_weights()
for module in self.fpn.values():
if hasattr(module, 'conv_out'):
caffe2_xavier_init(module.out_conv.conv)
for modules in [
self.adapt_convs.modules(),
self.extra_downsamples.modules()
]:
for module in modules:
if isinstance(module, nn.Conv2d):
caffe2_xavier_init(module)
|