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| #!/usr/bin/env python | |
| # -*- encoding: utf-8 -*- | |
| """ | |
| @Author : Peike Li | |
| @Contact : peike.li@yahoo.com | |
| @File : ocnet.py | |
| @Time : 8/4/19 3:36 PM | |
| @Desc : | |
| @License : This source code is licensed under the license found in the | |
| LICENSE file in the root directory of this source tree. | |
| """ | |
| import functools | |
| import torch | |
| import torch.nn as nn | |
| from torch.autograd import Variable | |
| from torch.nn import functional as F | |
| from modules import InPlaceABNSync | |
| BatchNorm2d = functools.partial(InPlaceABNSync, activation='none') | |
| class _SelfAttentionBlock(nn.Module): | |
| ''' | |
| The basic implementation for self-attention block/non-local block | |
| Input: | |
| N X C X H X W | |
| Parameters: | |
| in_channels : the dimension of the input feature map | |
| key_channels : the dimension after the key/query transform | |
| value_channels : the dimension after the value transform | |
| scale : choose the scale to downsample the input feature maps (save memory cost) | |
| Return: | |
| N X C X H X W | |
| position-aware context features.(w/o concate or add with the input) | |
| ''' | |
| def __init__(self, in_channels, key_channels, value_channels, out_channels=None, scale=1): | |
| super(_SelfAttentionBlock, self).__init__() | |
| self.scale = scale | |
| self.in_channels = in_channels | |
| self.out_channels = out_channels | |
| self.key_channels = key_channels | |
| self.value_channels = value_channels | |
| if out_channels == None: | |
| self.out_channels = in_channels | |
| self.pool = nn.MaxPool2d(kernel_size=(scale, scale)) | |
| self.f_key = nn.Sequential( | |
| nn.Conv2d(in_channels=self.in_channels, out_channels=self.key_channels, | |
| kernel_size=1, stride=1, padding=0), | |
| InPlaceABNSync(self.key_channels), | |
| ) | |
| self.f_query = self.f_key | |
| self.f_value = nn.Conv2d(in_channels=self.in_channels, out_channels=self.value_channels, | |
| kernel_size=1, stride=1, padding=0) | |
| self.W = nn.Conv2d(in_channels=self.value_channels, out_channels=self.out_channels, | |
| kernel_size=1, stride=1, padding=0) | |
| nn.init.constant(self.W.weight, 0) | |
| nn.init.constant(self.W.bias, 0) | |
| def forward(self, x): | |
| batch_size, h, w = x.size(0), x.size(2), x.size(3) | |
| if self.scale > 1: | |
| x = self.pool(x) | |
| value = self.f_value(x).view(batch_size, self.value_channels, -1) | |
| value = value.permute(0, 2, 1) | |
| query = self.f_query(x).view(batch_size, self.key_channels, -1) | |
| query = query.permute(0, 2, 1) | |
| key = self.f_key(x).view(batch_size, self.key_channels, -1) | |
| sim_map = torch.matmul(query, key) | |
| sim_map = (self.key_channels ** -.5) * sim_map | |
| sim_map = F.softmax(sim_map, dim=-1) | |
| context = torch.matmul(sim_map, value) | |
| context = context.permute(0, 2, 1).contiguous() | |
| context = context.view(batch_size, self.value_channels, *x.size()[2:]) | |
| context = self.W(context) | |
| if self.scale > 1: | |
| context = F.upsample(input=context, size=(h, w), mode='bilinear', align_corners=True) | |
| return context | |
| class SelfAttentionBlock2D(_SelfAttentionBlock): | |
| def __init__(self, in_channels, key_channels, value_channels, out_channels=None, scale=1): | |
| super(SelfAttentionBlock2D, self).__init__(in_channels, | |
| key_channels, | |
| value_channels, | |
| out_channels, | |
| scale) | |
| class BaseOC_Module(nn.Module): | |
| """ | |
| Implementation of the BaseOC module | |
| Parameters: | |
| in_features / out_features: the channels of the input / output feature maps. | |
| dropout: we choose 0.05 as the default value. | |
| size: you can apply multiple sizes. Here we only use one size. | |
| Return: | |
| features fused with Object context information. | |
| """ | |
| def __init__(self, in_channels, out_channels, key_channels, value_channels, dropout, sizes=([1])): | |
| super(BaseOC_Module, self).__init__() | |
| self.stages = [] | |
| self.stages = nn.ModuleList( | |
| [self._make_stage(in_channels, out_channels, key_channels, value_channels, size) for size in sizes]) | |
| self.conv_bn_dropout = nn.Sequential( | |
| nn.Conv2d(2 * in_channels, out_channels, kernel_size=1, padding=0), | |
| InPlaceABNSync(out_channels), | |
| nn.Dropout2d(dropout) | |
| ) | |
| def _make_stage(self, in_channels, output_channels, key_channels, value_channels, size): | |
| return SelfAttentionBlock2D(in_channels, | |
| key_channels, | |
| value_channels, | |
| output_channels, | |
| size) | |
| def forward(self, feats): | |
| priors = [stage(feats) for stage in self.stages] | |
| context = priors[0] | |
| for i in range(1, len(priors)): | |
| context += priors[i] | |
| output = self.conv_bn_dropout(torch.cat([context, feats], 1)) | |
| return output | |
| class BaseOC_Context_Module(nn.Module): | |
| """ | |
| Output only the context features. | |
| Parameters: | |
| in_features / out_features: the channels of the input / output feature maps. | |
| dropout: specify the dropout ratio | |
| fusion: We provide two different fusion method, "concat" or "add" | |
| size: we find that directly learn the attention weights on even 1/8 feature maps is hard. | |
| Return: | |
| features after "concat" or "add" | |
| """ | |
| def __init__(self, in_channels, out_channels, key_channels, value_channels, dropout, sizes=([1])): | |
| super(BaseOC_Context_Module, self).__init__() | |
| self.stages = [] | |
| self.stages = nn.ModuleList( | |
| [self._make_stage(in_channels, out_channels, key_channels, value_channels, size) for size in sizes]) | |
| self.conv_bn_dropout = nn.Sequential( | |
| nn.Conv2d(in_channels, out_channels, kernel_size=1, padding=0), | |
| InPlaceABNSync(out_channels), | |
| ) | |
| def _make_stage(self, in_channels, output_channels, key_channels, value_channels, size): | |
| return SelfAttentionBlock2D(in_channels, | |
| key_channels, | |
| value_channels, | |
| output_channels, | |
| size) | |
| def forward(self, feats): | |
| priors = [stage(feats) for stage in self.stages] | |
| context = priors[0] | |
| for i in range(1, len(priors)): | |
| context += priors[i] | |
| output = self.conv_bn_dropout(context) | |
| return output | |
| class ASP_OC_Module(nn.Module): | |
| def __init__(self, features, out_features=256, dilations=(12, 24, 36)): | |
| super(ASP_OC_Module, self).__init__() | |
| self.context = nn.Sequential(nn.Conv2d(features, out_features, kernel_size=3, padding=1, dilation=1, bias=True), | |
| InPlaceABNSync(out_features), | |
| BaseOC_Context_Module(in_channels=out_features, out_channels=out_features, | |
| key_channels=out_features // 2, value_channels=out_features, | |
| dropout=0, sizes=([2]))) | |
| self.conv2 = nn.Sequential(nn.Conv2d(features, out_features, kernel_size=1, padding=0, dilation=1, bias=False), | |
| InPlaceABNSync(out_features)) | |
| self.conv3 = nn.Sequential( | |
| nn.Conv2d(features, out_features, kernel_size=3, padding=dilations[0], dilation=dilations[0], bias=False), | |
| InPlaceABNSync(out_features)) | |
| self.conv4 = nn.Sequential( | |
| nn.Conv2d(features, out_features, kernel_size=3, padding=dilations[1], dilation=dilations[1], bias=False), | |
| InPlaceABNSync(out_features)) | |
| self.conv5 = nn.Sequential( | |
| nn.Conv2d(features, out_features, kernel_size=3, padding=dilations[2], dilation=dilations[2], bias=False), | |
| InPlaceABNSync(out_features)) | |
| self.conv_bn_dropout = nn.Sequential( | |
| nn.Conv2d(out_features * 5, out_features, kernel_size=1, padding=0, dilation=1, bias=False), | |
| InPlaceABNSync(out_features), | |
| nn.Dropout2d(0.1) | |
| ) | |
| def _cat_each(self, feat1, feat2, feat3, feat4, feat5): | |
| assert (len(feat1) == len(feat2)) | |
| z = [] | |
| for i in range(len(feat1)): | |
| z.append(torch.cat((feat1[i], feat2[i], feat3[i], feat4[i], feat5[i]), 1)) | |
| return z | |
| def forward(self, x): | |
| if isinstance(x, Variable): | |
| _, _, h, w = x.size() | |
| elif isinstance(x, tuple) or isinstance(x, list): | |
| _, _, h, w = x[0].size() | |
| else: | |
| raise RuntimeError('unknown input type') | |
| feat1 = self.context(x) | |
| feat2 = self.conv2(x) | |
| feat3 = self.conv3(x) | |
| feat4 = self.conv4(x) | |
| feat5 = self.conv5(x) | |
| if isinstance(x, Variable): | |
| out = torch.cat((feat1, feat2, feat3, feat4, feat5), 1) | |
| elif isinstance(x, tuple) or isinstance(x, list): | |
| out = self._cat_each(feat1, feat2, feat3, feat4, feat5) | |
| else: | |
| raise RuntimeError('unknown input type') | |
| output = self.conv_bn_dropout(out) | |
| return output | |