File size: 13,025 Bytes
41f97d1 |
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 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 |
import torch
import torch.nn as nn
import torch.nn.functional as F
import numpy as np
class Graph():
""" The Graph to model the skeletons
Args:
strategy (string): must be one of the follow candidates
- uniform: Uniform Labeling
- distance: Distance Partitioning
- spatial: Spatial Configuration
max_hop (int): the maximal distance between two connected nodes
dilation (int): controls the spacing between the kernel points
"""
def __init__(self,
strategy='spatial',
max_hop=1,
dilation=1):
self.max_hop = max_hop
self.dilation = dilation
self.get_edge()
self.hop_dis = get_hop_distance(self.num_node,
self.edge,
max_hop=max_hop)
self.get_adjacency(strategy)
def __str__(self):
return self.A
def get_edge(self):
# edge is a list of [child, parent] paris
self.num_node = 22
self_link = [(i, i) for i in range(self.num_node)]
neighbor_link = [(1,0), (2,1), (3,2), (4,3), (5,0), (6,5), (7,6), (8,7), (9,0), (10,9), (11,10), (12,11), \
(13,12), (14,11), (15,14), (16,15), (17,16), (18,11), (19,18), (20,19), (21,20)]
self.edge = self_link + neighbor_link
self.center = 0
def get_adjacency(self, strategy):
valid_hop = range(0, self.max_hop + 1, self.dilation)
adjacency = np.zeros((self.num_node, self.num_node))
for hop in valid_hop:
adjacency[self.hop_dis == hop] = 1
normalize_adjacency = normalize_digraph(adjacency)
if strategy == 'uniform':
A = np.zeros((1, self.num_node, self.num_node))
A[0] = normalize_adjacency
self.A = A
elif strategy == 'distance':
A = np.zeros((len(valid_hop), self.num_node, self.num_node))
for i, hop in enumerate(valid_hop):
A[i][self.hop_dis == hop] = normalize_adjacency[self.hop_dis ==
hop]
self.A = A
elif strategy == 'spatial':
A = []
for hop in valid_hop:
a_root = np.zeros((self.num_node, self.num_node))
a_close = np.zeros((self.num_node, self.num_node))
a_further = np.zeros((self.num_node, self.num_node))
for i in range(self.num_node):
for j in range(self.num_node):
if self.hop_dis[j, i] == hop:
if self.hop_dis[j, self.center] == self.hop_dis[
i, self.center]:
a_root[j, i] = normalize_adjacency[j, i]
elif self.hop_dis[j, self.center] > self.hop_dis[
i, self.center]:
a_close[j, i] = normalize_adjacency[j, i]
else:
a_further[j, i] = normalize_adjacency[j, i]
if hop == 0:
A.append(a_root)
else:
A.append(a_root + a_close)
A.append(a_further)
A = np.stack(A)
self.A = A
else:
raise ValueError("Do Not Exist This Strategy")
def get_hop_distance(num_node, edge, max_hop=1):
A = np.zeros((num_node, num_node))
for i, j in edge:
A[j, i] = 1
A[i, j] = 1
# compute hop steps
hop_dis = np.zeros((num_node, num_node)) + np.inf
transfer_mat = [np.linalg.matrix_power(A, d) for d in range(max_hop + 1)]
arrive_mat = (np.stack(transfer_mat) > 0)
for d in range(max_hop, -1, -1):
hop_dis[arrive_mat[d]] = d
return hop_dis
def normalize_digraph(A):
Dl = np.sum(A, 0)
num_node = A.shape[0]
Dn = np.zeros((num_node, num_node))
for i in range(num_node):
if Dl[i] > 0:
Dn[i, i] = Dl[i]**(-1)
AD = np.dot(A, Dn)
return AD
def normalize_undigraph(A):
Dl = np.sum(A, 0)
num_node = A.shape[0]
Dn = np.zeros((num_node, num_node))
for i in range(num_node):
if Dl[i] > 0:
Dn[i, i] = Dl[i]**(-0.5)
DAD = np.dot(np.dot(Dn, A), Dn)
return DAD
def zero(x):
return 0
def iden(x):
return x
class ConvTemporalGraphical(nn.Module):
r"""The basic module for applying a graph convolution.
Args:
in_channels (int): Number of channels in the input sequence data
out_channels (int): Number of channels produced by the convolution
kernel_size (int): Size of the graph convolving kernel
t_kernel_size (int): Size of the temporal convolving kernel
t_stride (int, optional): Stride of the temporal convolution. Default: 1
t_padding (int, optional): Temporal zero-padding added to both sides of
the input. Default: 0
t_dilation (int, optional): Spacing between temporal kernel elements.
Default: 1
bias (bool, optional): If ``True``, adds a learnable bias to the output.
Default: ``True``
Shape:
- Input[0]: Input graph sequence in :math:`(N, in_channels, T_{in}, V)` format
- Input[1]: Input graph adjacency matrix in :math:`(K, V, V)` format
- Output[0]: Output graph sequence in :math:`(N, out_channels, T_{out}, V)` format
- Output[1]: Graph adjacency matrix for output data in :math:`(K, V, V)` format
where
:math:`N` is a batch size,
:math:`K` is the spatial kernel size, as :math:`K == kernel_size[1]`,
:math:`T_{in}/T_{out}` is a length of input/output sequence,
:math:`V` is the number of graph nodes.
"""
def __init__(self,
in_channels,
out_channels,
kernel_size,
t_kernel_size=1,
t_stride=1,
t_padding=0,
t_dilation=1,
bias=True):
super().__init__()
self.kernel_size = kernel_size
self.conv = nn.Conv2d(in_channels,
out_channels * kernel_size,
kernel_size=(t_kernel_size, 1),
padding=(t_padding, 0),
stride=(t_stride, 1),
dilation=(t_dilation, 1),
bias=bias)
def forward(self, x, A):
assert A.size(0) == self.kernel_size
x = self.conv(x)
n, kc, t, v = x.size()
x = x.view(n, self.kernel_size, kc // self.kernel_size, t, v)
x = torch.einsum('nkctv,kvw->nctw', (x, A))
return x.contiguous(), A
class st_gcn_block(nn.Module):
r"""Applies a spatial temporal graph convolution over an input graph sequence.
Args:
in_channels (int): Number of channels in the input sequence data
out_channels (int): Number of channels produced by the convolution
kernel_size (tuple): Size of the temporal convolving kernel and graph convolving kernel
stride (int, optional): Stride of the temporal convolution. Default: 1
dropout (int, optional): Dropout rate of the final output. Default: 0
residual (bool, optional): If ``True``, applies a residual mechanism. Default: ``True``
Shape:
- Input[0]: Input graph sequence in :math:`(N, in_channels, T_{in}, V)` format
- Input[1]: Input graph adjacency matrix in :math:`(K, V, V)` format
- Output[0]: Outpu graph sequence in :math:`(N, out_channels, T_{out}, V)` format
- Output[1]: Graph adjacency matrix for output data in :math:`(K, V, V)` format
where
:math:`N` is a batch size,
:math:`K` is the spatial kernel size, as :math:`K == kernel_size[1]`,
:math:`T_{in}/T_{out}` is a length of input/output sequence,
:math:`V` is the number of graph nodes.
"""
def __init__(self,
in_channels,
out_channels,
kernel_size,
stride=1,
dropout=0,
residual=True):
super().__init__()
assert len(kernel_size) == 2
assert kernel_size[0] % 2 == 1
padding = ((kernel_size[0] - 1) // 2, 0)
self.gcn = ConvTemporalGraphical(in_channels, out_channels,
kernel_size[1])
self.tcn = nn.Sequential(
nn.BatchNorm2d(out_channels),
nn.ReLU(inplace=True),
nn.Conv2d(
out_channels,
out_channels,
(kernel_size[0], 1),
(stride, 1),
padding,
),
nn.BatchNorm2d(out_channels),
nn.Dropout(dropout, inplace=True),
)
if not residual:
self.residual = zero
elif (in_channels == out_channels) and (stride == 1):
self.residual = iden
else:
self.residual = nn.Sequential(
nn.Conv2d(in_channels,
out_channels,
kernel_size=1,
stride=(stride, 1)),
nn.BatchNorm2d(out_channels),
)
self.relu = nn.ReLU(inplace=True)
def forward(self, x, A):
res = self.residual(x)
x, A = self.gcn(x, A)
x = self.tcn(x) + res
return self.relu(x), A
class ST_GCN_18(nn.Module):
r"""Spatial temporal graph convolutional networks.
Args:
in_channels (int): Number of channels in the input data
num_class (int): Number of classes for the classification task
graph_cfg (dict): The arguments for building the graph
edge_importance_weighting (bool): If ``True``, adds a learnable
importance weighting to the edges of the graph
**kwargs (optional): Other parameters for graph convolution units
Shape:
- Input: :math:`(N, in_channels, T_{in}, V_{in}, M_{in})`
- Output: :math:`(N, num_class)` where
:math:`N` is a batch size,
:math:`T_{in}` is a length of input sequence,
:math:`V_{in}` is the number of graph nodes,
:math:`M_{in}` is the number of instance in a frame.
"""
def __init__(self,
in_channels,
edge_importance_weighting=True,
data_bn=True,
**kwargs):
super().__init__()
# load graph
self.graph = Graph()
A = torch.tensor(self.graph.A,
dtype=torch.float32,
requires_grad=False)
self.register_buffer('A', A)
# build networks
spatial_kernel_size = A.size(0)
temporal_kernel_size = 9
kernel_size = (temporal_kernel_size, spatial_kernel_size)
self.data_bn = nn.BatchNorm1d(in_channels *
A.size(1)) if data_bn else iden
kwargs0 = {k: v for k, v in kwargs.items() if k != 'dropout'}
self.st_gcn_networks = nn.ModuleList((
st_gcn_block(in_channels,
64,
kernel_size,
1,
residual=False,
**kwargs0),
st_gcn_block(64, 64, kernel_size, 1, **kwargs),
st_gcn_block(64, 64, kernel_size, 1, **kwargs),
st_gcn_block(64, 64, kernel_size, 1, **kwargs),
st_gcn_block(64, 128, kernel_size, 2, **kwargs),
st_gcn_block(128, 128, kernel_size, 1, **kwargs),
st_gcn_block(128, 128, kernel_size, 1, **kwargs),
st_gcn_block(128, 256, kernel_size, 2, **kwargs),
st_gcn_block(256, 256, kernel_size, 1, **kwargs),
st_gcn_block(256, 512, kernel_size, 1, **kwargs),
))
# initialize parameters for edge importance weighting
if edge_importance_weighting:
self.edge_importance = nn.ParameterList([
nn.Parameter(torch.ones(self.A.size()))
for i in self.st_gcn_networks
])
else:
self.edge_importance = [1] * len(self.st_gcn_networks)
def forward(self, x):
# data normalization
N, C, T, V, M = x.size()
x = x.permute(0, 4, 3, 1, 2).contiguous()
x = x.view(N * M, V * C, T)
x = self.data_bn(x)
x = x.view(N, M, V, C, T)
x = x.permute(0, 1, 3, 4, 2).contiguous()
x = x.view(N * M, C, T, V)
# forward
for gcn, importance in zip(self.st_gcn_networks, self.edge_importance):
x, _ = gcn(x, self.A * importance)
# global pooling
x = F.avg_pool2d(x, x.size()[2:]) # (b, 512, t, joint)
x = x.view(N, M, -1, 1, 1).mean(dim=1)
return x |