# Source: https://github.com/zijundeng/pytorch-semantic-segmentation/tree/master/models (MIT)
"""
Implementation of `Fully Convolutional Networks for Semantic Segmentation <http://www.cv-foundation.org/openaccess/content_cvpr_2015/papers/Long_Fully_Convolutional_Networks_2015_CVPR_paper.pdf>`_
"""
import torch
from torch import nn
from torchvision import models
from .fcn_utils import get_upsampling_weight
from .config import vgg16_caffe_path
__all__ = ['FCN16VGG']
[docs]class FCN16VGG(nn.Module):
def __init__(self, num_classes, pretrained=True, **kwargs):
super(FCN16VGG, self).__init__()
vgg = models.vgg16()
if pretrained:
vgg.load_state_dict(torch.load(vgg16_caffe_path))
features, classifier = list(vgg.features.children()), list(vgg.classifier.children())
features[0].padding = (100, 100)
for f in features:
if 'MaxPool' in f.__class__.__name__:
f.ceil_mode = True
elif 'ReLU' in f.__class__.__name__:
f.inplace = True
self.features4 = nn.Sequential(*features[: 24])
self.features5 = nn.Sequential(*features[24:])
self.score_pool4 = nn.Conv2d(512, num_classes, kernel_size=1)
self.score_pool4.weight.data.zero_()
self.score_pool4.bias.data.zero_()
fc6 = nn.Conv2d(512, 4096, kernel_size=7)
fc6.weight.data.copy_(classifier[0].weight.data.view(4096, 512, 7, 7))
fc6.bias.data.copy_(classifier[0].bias.data)
fc7 = nn.Conv2d(4096, 4096, kernel_size=1)
fc7.weight.data.copy_(classifier[3].weight.data.view(4096, 4096, 1, 1))
fc7.bias.data.copy_(classifier[3].bias.data)
score_fr = nn.Conv2d(4096, num_classes, kernel_size=1)
score_fr.weight.data.zero_()
score_fr.bias.data.zero_()
self.score_fr = nn.Sequential(
fc6, nn.ReLU(inplace=True), nn.Dropout(), fc7, nn.ReLU(inplace=True), nn.Dropout(), score_fr
)
self.upscore2 = nn.ConvTranspose2d(num_classes, num_classes, kernel_size=4, stride=2, bias=False)
self.upscore16 = nn.ConvTranspose2d(num_classes, num_classes, kernel_size=32, stride=16, bias=False)
self.upscore2.weight.data.copy_(get_upsampling_weight(num_classes, num_classes, 4))
self.upscore16.weight.data.copy_(get_upsampling_weight(num_classes, num_classes, 32))
def forward(self, x):
x_size = x.size()
pool4 = self.features4(x)
pool5 = self.features5(pool4)
score_fr = self.score_fr(pool5)
upscore2 = self.upscore2(score_fr)
score_pool4 = self.score_pool4(0.01 * pool4)
upscore16 = self.upscore16(score_pool4[:, :, 5: (5 + upscore2.size()[2]), 5: (5 + upscore2.size()[3])]
+ upscore2)
return upscore16[:, :, 27: (27 + x_size[2]), 27: (27 + x_size[3])].contiguous()