hourglassnet网络解析
作者：互联网
hourglassnet中文名称是沙漏网络，起初用于人体关键点检测，代码，https://github.com/bearpaw/pytorch-pose
后来被广泛的应用到其他领域，我知道的有双目深度估计，关于双目深度估计，自己最近会写一篇blog，这里先简单介绍一下。双目深度估计第一次用hourglassnet是在psmnet（https://github.com/JiaRenChang/PSMNet）中使用的的，后来的很多双目深度估计的工作也有很多继承这种hourglass的使用方法，比如gwcnet（https://github.com/xy-guo/GwcNet）
在这里就详细解说一下hourglassnet的网络结构，hourglassnet作者已经公开了代码，这里参考这个代码：https://github.com/bearpaw/pytorch-pose/blob/master/pose/models/hourglass.py
代码如下
import torch.nn as nn
import torch.nn.functional as F
from tensorboardX import SummaryWriter
# from .preresnet import BasicBlock, Bottleneck
import torch
from torch.autograd import Variable
class Bottleneck(nn.Module):
expansion = 2
def __init__(self, inplanes, planes, stride=1, downsample=None):
super(Bottleneck, self).__init__()
self.bn1 = nn.BatchNorm2d(inplanes)
self.conv1 = nn.Conv2d(inplanes, planes, kernel_size=1, bias=True)
self.bn2 = nn.BatchNorm2d(planes)
self.conv2 = nn.Conv2d(planes, planes, kernel_size=3, stride=stride,
padding=1, bias=True)
self.bn3 = nn.BatchNorm2d(planes)
self.conv3 = nn.Conv2d(planes, planes * 2, kernel_size=1, bias=True)
self.relu = nn.ReLU(inplace=True)
self.downsample = downsample
self.stride = stride
def forward(self, x):
residual = x
out = self.bn1(x)
out = self.relu(out)
out = self.conv1(out)
out = self.bn2(out)
out = self.relu(out)
out = self.conv2(out)
out = self.bn3(out)
out = self.relu(out)
out = self.conv3(out)
if self.downsample is not None:
residual = self.downsample(x)
out += residual
return out
# houglass实际上是一个大的auto encoder
class Hourglass(nn.Module):
def __init__(self, block, num_blocks, planes, depth):
super(Hourglass, self).__init__()
self.depth = depth
self.block = block
self.hg = self._make_hour_glass(block, num_blocks, planes, depth)
def _make_residual(self, block, num_blocks, planes):
layers = []
for i in range(0, num_blocks):
layers.append(block(planes*block.expansion, planes))
return nn.Sequential(*layers)
def _make_hour_glass(self, block, num_blocks, planes, depth):
hg = []
for i in range(depth):
res = []
for j in range(3):
res.append(self._make_residual(block, num_blocks, planes))
if i == 0:
res.append(self._make_residual(block, num_blocks, planes))
hg.append(nn.ModuleList(res))
return nn.ModuleList(hg)
def _hour_glass_forward(self, n, x):
up1 = self.hg[n-1][0](x)
low1 = F.max_pool2d(x, 2, stride=2)
low1 = self.hg[n-1][1](low1)
if n > 1:
low2 = self._hour_glass_forward(n-1, low1)
else:
low2 = self.hg[n-1][3](low1)
low3 = self.hg[n-1][2](low2)
up2 = F.interpolate(low3, scale_factor=2)
out = up1 + up2
return out
def forward(self, x):
return self._hour_glass_forward(self.depth, x)
class HourglassNet(nn.Module):
'''Hourglass model from Newell et al ECCV 2016'''
def __init__(self, block, num_stacks=2, num_blocks=4, num_classes=16):
super(HourglassNet, self).__init__()
self.inplanes = 64
self.num_feats = 128
self.num_stacks = num_stacks
self.conv1 = nn.Conv2d(3, self.inplanes, kernel_size=7, stride=2, padding=3,
bias=True)
self.bn1 = nn.BatchNorm2d(self.inplanes)
self.relu = nn.ReLU(inplace=True)
self.layer1 = self._make_residual(block, self.inplanes, 1)
self.layer2 = self._make_residual(block, self.inplanes, 1)
self.layer3 = self._make_residual(block, self.num_feats, 1)
self.maxpool = nn.MaxPool2d(2, stride=2)
# build hourglass modules
ch = self.num_feats*block.expansion
hg, res, fc, score, fc_, score_ = [], [], [], [], [], []
for i in range(num_stacks):
hg.append(Hourglass(block, num_blocks, self.num_feats, 4))
res.append(self._make_residual(block, self.num_feats, num_blocks))
fc.append(self._make_fc(ch, ch))
score.append(nn.Conv2d(ch, num_classes, kernel_size=1, bias=True))
if i < num_stacks-1:
fc_.append(nn.Conv2d(ch, ch, kernel_size=1, bias=True))
score_.append(nn.Conv2d(num_classes, ch, kernel_size=1, bias=True))
self.hg = nn.ModuleList(hg)
self.res = nn.ModuleList(res)
self.fc = nn.ModuleList(fc)
self.score = nn.ModuleList(score)
self.fc_ = nn.ModuleList(fc_)
self.score_ = nn.ModuleList(score_)
def _make_residual(self, block, planes, blocks, stride=1):
downsample = None
if stride != 1 or self.inplanes != planes * block.expansion:
downsample = nn.Sequential(
nn.Conv2d(self.inplanes, planes * block.expansion,
kernel_size=1, stride=stride, bias=True),
)
layers = []
layers.append(block(self.inplanes, planes, stride, downsample))
self.inplanes = planes * block.expansion
for i in range(1, blocks):
layers.append(block(self.inplanes, planes))
return nn.Sequential(*layers)
def _make_fc(self, inplanes, outplanes):
bn = nn.BatchNorm2d(inplanes)
conv = nn.Conv2d(inplanes, outplanes, kernel_size=1, bias=True)
return nn.Sequential(
conv,
bn,
self.relu,
)
def forward(self, x):
out = []
x = self.conv1(x)
x = self.bn1(x)
x = self.relu(x)
x = self.layer1(x)
x = self.maxpool(x)
x = self.layer2(x)
x = self.layer3(x)
for i in range(self.num_stacks):
y = self.hg[i](x)
y = self.res[i](y)
y = self.fc[i](y)
score = self.score[i](y)
out.append(score)
if i < self.num_stacks-1:
fc_ = self.fc_[i](y)
score_ = self.score_[i](score)
x = x + fc_ + score_
return out
if __name__ == "__main__":
model = HourglassNet(Bottleneck, num_stacks=2, num_blocks=4, num_classes=2)
model2 = Hourglass(block=Bottleneck, num_blocks=4, planes=128, depth=4)
input_data = Variable(torch.rand(2, 3, 256, 256))
input_data2 = Variable(torch.rand(2, 256, 64, 64))
output = model(input_data)
print(output)
# writer = SummaryWriter(log_dir='../log', comment='source_arc')
# with writer:
# writer.add_graph(model2, (input_data2, ))
View Code
这里一步一步讲
以往的auto-ecoder最小的单元可能是一个卷积层，这里作者最小的单元是一个Bottleneck
作者先写了hourglss这个module，hourglass具体的网络结构如下
标签：解析,nn,self,网络,num,planes,hourglassnet,block,out 来源： https://www.cnblogs.com/yongjieShi/p/11320310.html