Spaces:
Runtime error
Runtime error
File size: 5,882 Bytes
b334e29 |
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 |
import torch
import torch.nn as nn
import torch.nn.functional as F
from mmcv.cnn import VGG, constant_init, kaiming_init, normal_init, xavier_init
from mmcv.runner import load_checkpoint
from mmdet.utils import get_root_logger
from ..builder import BACKBONES
@BACKBONES.register_module()
class SSDVGG(VGG):
"""VGG Backbone network for single-shot-detection.
Args:
input_size (int): width and height of input, from {300, 512}.
depth (int): Depth of vgg, from {11, 13, 16, 19}.
out_indices (Sequence[int]): Output from which stages.
Example:
>>> self = SSDVGG(input_size=300, depth=11)
>>> self.eval()
>>> inputs = torch.rand(1, 3, 300, 300)
>>> level_outputs = self.forward(inputs)
>>> for level_out in level_outputs:
... print(tuple(level_out.shape))
(1, 1024, 19, 19)
(1, 512, 10, 10)
(1, 256, 5, 5)
(1, 256, 3, 3)
(1, 256, 1, 1)
"""
extra_setting = {
300: (256, 'S', 512, 128, 'S', 256, 128, 256, 128, 256),
512: (256, 'S', 512, 128, 'S', 256, 128, 'S', 256, 128, 'S', 256, 128),
}
def __init__(self,
input_size,
depth,
with_last_pool=False,
ceil_mode=True,
out_indices=(3, 4),
out_feature_indices=(22, 34),
l2_norm_scale=20.):
# TODO: in_channels for mmcv.VGG
super(SSDVGG, self).__init__(
depth,
with_last_pool=with_last_pool,
ceil_mode=ceil_mode,
out_indices=out_indices)
assert input_size in (300, 512)
self.input_size = input_size
self.features.add_module(
str(len(self.features)),
nn.MaxPool2d(kernel_size=3, stride=1, padding=1))
self.features.add_module(
str(len(self.features)),
nn.Conv2d(512, 1024, kernel_size=3, padding=6, dilation=6))
self.features.add_module(
str(len(self.features)), nn.ReLU(inplace=True))
self.features.add_module(
str(len(self.features)), nn.Conv2d(1024, 1024, kernel_size=1))
self.features.add_module(
str(len(self.features)), nn.ReLU(inplace=True))
self.out_feature_indices = out_feature_indices
self.inplanes = 1024
self.extra = self._make_extra_layers(self.extra_setting[input_size])
self.l2_norm = L2Norm(
self.features[out_feature_indices[0] - 1].out_channels,
l2_norm_scale)
def init_weights(self, pretrained=None):
"""Initialize the weights in backbone.
Args:
pretrained (str, optional): Path to pre-trained weights.
Defaults to None.
"""
if isinstance(pretrained, str):
logger = get_root_logger()
load_checkpoint(self, pretrained, strict=False, logger=logger)
elif pretrained is None:
for m in self.features.modules():
if isinstance(m, nn.Conv2d):
kaiming_init(m)
elif isinstance(m, nn.BatchNorm2d):
constant_init(m, 1)
elif isinstance(m, nn.Linear):
normal_init(m, std=0.01)
else:
raise TypeError('pretrained must be a str or None')
for m in self.extra.modules():
if isinstance(m, nn.Conv2d):
xavier_init(m, distribution='uniform')
constant_init(self.l2_norm, self.l2_norm.scale)
def forward(self, x):
"""Forward function."""
outs = []
for i, layer in enumerate(self.features):
x = layer(x)
if i in self.out_feature_indices:
outs.append(x)
for i, layer in enumerate(self.extra):
x = F.relu(layer(x), inplace=True)
if i % 2 == 1:
outs.append(x)
outs[0] = self.l2_norm(outs[0])
if len(outs) == 1:
return outs[0]
else:
return tuple(outs)
def _make_extra_layers(self, outplanes):
layers = []
kernel_sizes = (1, 3)
num_layers = 0
outplane = None
for i in range(len(outplanes)):
if self.inplanes == 'S':
self.inplanes = outplane
continue
k = kernel_sizes[num_layers % 2]
if outplanes[i] == 'S':
outplane = outplanes[i + 1]
conv = nn.Conv2d(
self.inplanes, outplane, k, stride=2, padding=1)
else:
outplane = outplanes[i]
conv = nn.Conv2d(
self.inplanes, outplane, k, stride=1, padding=0)
layers.append(conv)
self.inplanes = outplanes[i]
num_layers += 1
if self.input_size == 512:
layers.append(nn.Conv2d(self.inplanes, 256, 4, padding=1))
return nn.Sequential(*layers)
class L2Norm(nn.Module):
def __init__(self, n_dims, scale=20., eps=1e-10):
"""L2 normalization layer.
Args:
n_dims (int): Number of dimensions to be normalized
scale (float, optional): Defaults to 20..
eps (float, optional): Used to avoid division by zero.
Defaults to 1e-10.
"""
super(L2Norm, self).__init__()
self.n_dims = n_dims
self.weight = nn.Parameter(torch.Tensor(self.n_dims))
self.eps = eps
self.scale = scale
def forward(self, x):
"""Forward function."""
# normalization layer convert to FP32 in FP16 training
x_float = x.float()
norm = x_float.pow(2).sum(1, keepdim=True).sqrt() + self.eps
return (self.weight[None, :, None, None].float().expand_as(x_float) *
x_float / norm).type_as(x)
|