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import torch |
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import torch.nn as nn |
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from mmcv.cnn import ConvModule |
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from mmseg.ops import resize |
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from ..builder import HEADS |
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from .decode_head import BaseDecodeHead |
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class ASPPModule(nn.ModuleList): |
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"""Atrous Spatial Pyramid Pooling (ASPP) Module. |
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Args: |
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dilations (tuple[int]): Dilation rate of each layer. |
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in_channels (int): Input channels. |
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channels (int): Channels after modules, before conv_seg. |
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conv_cfg (dict|None): Config of conv layers. |
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norm_cfg (dict|None): Config of norm layers. |
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act_cfg (dict): Config of activation layers. |
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""" |
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def __init__(self, dilations, in_channels, channels, conv_cfg, norm_cfg, |
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act_cfg): |
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super(ASPPModule, self).__init__() |
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self.dilations = dilations |
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self.in_channels = in_channels |
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self.channels = channels |
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self.conv_cfg = conv_cfg |
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self.norm_cfg = norm_cfg |
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self.act_cfg = act_cfg |
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for dilation in dilations: |
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self.append( |
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ConvModule( |
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self.in_channels, |
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self.channels, |
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1 if dilation == 1 else 3, |
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dilation=dilation, |
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padding=0 if dilation == 1 else dilation, |
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conv_cfg=self.conv_cfg, |
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norm_cfg=self.norm_cfg, |
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act_cfg=self.act_cfg)) |
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def forward(self, x): |
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"""Forward function.""" |
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aspp_outs = [] |
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for aspp_module in self: |
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aspp_outs.append(aspp_module(x)) |
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return aspp_outs |
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@HEADS.register_module() |
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class ASPPHead(BaseDecodeHead): |
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"""Rethinking Atrous Convolution for Semantic Image Segmentation. |
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This head is the implementation of `DeepLabV3 |
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<https://arxiv.org/abs/1706.05587>`_. |
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Args: |
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dilations (tuple[int]): Dilation rates for ASPP module. |
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Default: (1, 6, 12, 18). |
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""" |
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def __init__(self, dilations=(1, 6, 12, 18), **kwargs): |
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super(ASPPHead, self).__init__(**kwargs) |
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assert isinstance(dilations, (list, tuple)) |
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self.dilations = dilations |
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self.image_pool = nn.Sequential( |
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nn.AdaptiveAvgPool2d(1), |
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ConvModule( |
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self.in_channels, |
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self.channels, |
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1, |
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conv_cfg=self.conv_cfg, |
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norm_cfg=self.norm_cfg, |
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act_cfg=self.act_cfg)) |
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self.aspp_modules = ASPPModule( |
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dilations, |
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self.in_channels, |
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self.channels, |
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conv_cfg=self.conv_cfg, |
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norm_cfg=self.norm_cfg, |
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act_cfg=self.act_cfg) |
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self.bottleneck = ConvModule( |
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(len(dilations) + 1) * self.channels, |
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self.channels, |
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3, |
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padding=1, |
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conv_cfg=self.conv_cfg, |
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norm_cfg=self.norm_cfg, |
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act_cfg=self.act_cfg) |
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def forward(self, inputs): |
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"""Forward function.""" |
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x = self._transform_inputs(inputs) |
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aspp_outs = [ |
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resize( |
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self.image_pool(x), |
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size=x.size()[2:], |
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mode='bilinear', |
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align_corners=self.align_corners) |
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] |
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aspp_outs.extend(self.aspp_modules(x)) |
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aspp_outs = torch.cat(aspp_outs, dim=1) |
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output = self.bottleneck(aspp_outs) |
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output = self.cls_seg(output) |
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return output |
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