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# This script is borrowed from https://github.com/nkolot/SPIN/blob/master/models/hmr.py
import torch
import torch.nn as nn
import torchvision.models.resnet as resnet
import numpy as np
import math
from lib.pymaf.utils.geometry import rot6d_to_rotmat
import logging
logger = logging.getLogger(__name__)
BN_MOMENTUM = 0.1
class Bottleneck(nn.Module):
""" Redefinition of Bottleneck residual block
Adapted from the official PyTorch implementation
"""
expansion = 4
def __init__(self, inplanes, planes, stride=1, downsample=None):
super().__init__()
self.conv1 = nn.Conv2d(inplanes, planes, kernel_size=1, bias=False)
self.bn1 = nn.BatchNorm2d(planes)
self.conv2 = nn.Conv2d(planes,
planes,
kernel_size=3,
stride=stride,
padding=1,
bias=False)
self.bn2 = nn.BatchNorm2d(planes)
self.conv3 = nn.Conv2d(planes, planes * 4, kernel_size=1, bias=False)
self.bn3 = nn.BatchNorm2d(planes * 4)
self.relu = nn.ReLU(inplace=True)
self.downsample = downsample
self.stride = stride
def forward(self, x):
residual = x
out = self.conv1(x)
out = self.bn1(out)
out = self.relu(out)
out = self.conv2(out)
out = self.bn2(out)
out = self.relu(out)
out = self.conv3(out)
out = self.bn3(out)
if self.downsample is not None:
residual = self.downsample(x)
out += residual
out = self.relu(out)
return out
class ResNet_Backbone(nn.Module):
""" Feature Extrator with ResNet backbone
"""
def __init__(self, model='res50', pretrained=True):
if model == 'res50':
block, layers = Bottleneck, [3, 4, 6, 3]
else:
pass # TODO
self.inplanes = 64
super().__init__()
npose = 24 * 6
self.conv1 = nn.Conv2d(3,
64,
kernel_size=7,
stride=2,
padding=3,
bias=False)
self.bn1 = nn.BatchNorm2d(64)
self.relu = nn.ReLU(inplace=True)
self.maxpool = nn.MaxPool2d(kernel_size=3, stride=2, padding=1)
self.layer1 = self._make_layer(block, 64, layers[0])
self.layer2 = self._make_layer(block, 128, layers[1], stride=2)
self.layer3 = self._make_layer(block, 256, layers[2], stride=2)
self.layer4 = self._make_layer(block, 512, layers[3], stride=2)
self.avgpool = nn.AvgPool2d(7, stride=1)
if pretrained:
resnet_imagenet = resnet.resnet50(pretrained=True)
self.load_state_dict(resnet_imagenet.state_dict(), strict=False)
logger.info('loaded resnet50 imagenet pretrained model')
def _make_layer(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=False),
nn.BatchNorm2d(planes * block.expansion),
)
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_deconv_layer(self, num_layers, num_filters, num_kernels):
assert num_layers == len(num_filters), \
'ERROR: num_deconv_layers is different len(num_deconv_filters)'
assert num_layers == len(num_kernels), \
'ERROR: num_deconv_layers is different len(num_deconv_filters)'
def _get_deconv_cfg(deconv_kernel, index):
if deconv_kernel == 4:
padding = 1
output_padding = 0
elif deconv_kernel == 3:
padding = 1
output_padding = 1
elif deconv_kernel == 2:
padding = 0
output_padding = 0
return deconv_kernel, padding, output_padding
layers = []
for i in range(num_layers):
kernel, padding, output_padding = _get_deconv_cfg(
num_kernels[i], i)
planes = num_filters[i]
layers.append(
nn.ConvTranspose2d(in_channels=self.inplanes,
out_channels=planes,
kernel_size=kernel,
stride=2,
padding=padding,
output_padding=output_padding,
bias=self.deconv_with_bias))
layers.append(nn.BatchNorm2d(planes, momentum=BN_MOMENTUM))
layers.append(nn.ReLU(inplace=True))
self.inplanes = planes
return nn.Sequential(*layers)
def forward(self, x):
batch_size = x.shape[0]
x = self.conv1(x)
x = self.bn1(x)
x = self.relu(x)
x = self.maxpool(x)
x1 = self.layer1(x)
x2 = self.layer2(x1)
x3 = self.layer3(x2)
x4 = self.layer4(x3)
xf = self.avgpool(x4)
xf = xf.view(xf.size(0), -1)
x_featmap = x4
return x_featmap, xf
class HMR(nn.Module):
""" SMPL Iterative Regressor with ResNet50 backbone
"""
def __init__(self, block, layers, smpl_mean_params):
self.inplanes = 64
super().__init__()
npose = 24 * 6
self.conv1 = nn.Conv2d(3,
64,
kernel_size=7,
stride=2,
padding=3,
bias=False)
self.bn1 = nn.BatchNorm2d(64)
self.relu = nn.ReLU(inplace=True)
self.maxpool = nn.MaxPool2d(kernel_size=3, stride=2, padding=1)
self.layer1 = self._make_layer(block, 64, layers[0])
self.layer2 = self._make_layer(block, 128, layers[1], stride=2)
self.layer3 = self._make_layer(block, 256, layers[2], stride=2)
self.layer4 = self._make_layer(block, 512, layers[3], stride=2)
self.avgpool = nn.AvgPool2d(7, stride=1)
self.fc1 = nn.Linear(512 * block.expansion + npose + 13, 1024)
self.drop1 = nn.Dropout()
self.fc2 = nn.Linear(1024, 1024)
self.drop2 = nn.Dropout()
self.decpose = nn.Linear(1024, npose)
self.decshape = nn.Linear(1024, 10)
self.deccam = nn.Linear(1024, 3)
nn.init.xavier_uniform_(self.decpose.weight, gain=0.01)
nn.init.xavier_uniform_(self.decshape.weight, gain=0.01)
nn.init.xavier_uniform_(self.deccam.weight, gain=0.01)
for m in self.modules():
if isinstance(m, nn.Conv2d):
n = m.kernel_size[0] * m.kernel_size[1] * m.out_channels
m.weight.data.normal_(0, math.sqrt(2. / n))
elif isinstance(m, nn.BatchNorm2d):
m.weight.data.fill_(1)
m.bias.data.zero_()
mean_params = np.load(smpl_mean_params)
init_pose = torch.from_numpy(mean_params['pose'][:]).unsqueeze(0)
init_shape = torch.from_numpy(
mean_params['shape'][:].astype('float32')).unsqueeze(0)
init_cam = torch.from_numpy(mean_params['cam']).unsqueeze(0)
self.register_buffer('init_pose', init_pose)
self.register_buffer('init_shape', init_shape)
self.register_buffer('init_cam', init_cam)
def _make_layer(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=False),
nn.BatchNorm2d(planes * block.expansion),
)
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 forward(self,
x,
init_pose=None,
init_shape=None,
init_cam=None,
n_iter=3):
batch_size = x.shape[0]
if init_pose is None:
init_pose = self.init_pose.expand(batch_size, -1)
if init_shape is None:
init_shape = self.init_shape.expand(batch_size, -1)
if init_cam is None:
init_cam = self.init_cam.expand(batch_size, -1)
x = self.conv1(x)
x = self.bn1(x)
x = self.relu(x)
x = self.maxpool(x)
x1 = self.layer1(x)
x2 = self.layer2(x1)
x3 = self.layer3(x2)
x4 = self.layer4(x3)
xf = self.avgpool(x4)
xf = xf.view(xf.size(0), -1)
pred_pose = init_pose
pred_shape = init_shape
pred_cam = init_cam
for i in range(n_iter):
xc = torch.cat([xf, pred_pose, pred_shape, pred_cam], 1)
xc = self.fc1(xc)
xc = self.drop1(xc)
xc = self.fc2(xc)
xc = self.drop2(xc)
pred_pose = self.decpose(xc) + pred_pose
pred_shape = self.decshape(xc) + pred_shape
pred_cam = self.deccam(xc) + pred_cam
pred_rotmat = rot6d_to_rotmat(pred_pose).view(batch_size, 24, 3, 3)
return pred_rotmat, pred_shape, pred_cam
def hmr(smpl_mean_params, pretrained=True, **kwargs):
""" Constructs an HMR model with ResNet50 backbone.
Args:
pretrained (bool): If True, returns a model pre-trained on ImageNet
"""
model = HMR(Bottleneck, [3, 4, 6, 3], smpl_mean_params, **kwargs)
if pretrained:
resnet_imagenet = resnet.resnet50(pretrained=True)
model.load_state_dict(resnet_imagenet.state_dict(), strict=False)
return model