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import torch.nn as nn |
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from mmcv.cnn import ConvModule, bias_init_with_prob, normal_init |
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from mmcv.ops import MaskedConv2d |
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from ..builder import HEADS |
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from .guided_anchor_head import FeatureAdaption, GuidedAnchorHead |
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@HEADS.register_module() |
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class GARetinaHead(GuidedAnchorHead): |
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"""Guided-Anchor-based RetinaNet head.""" |
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def __init__(self, |
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num_classes, |
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in_channels, |
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stacked_convs=4, |
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conv_cfg=None, |
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norm_cfg=None, |
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**kwargs): |
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self.stacked_convs = stacked_convs |
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self.conv_cfg = conv_cfg |
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self.norm_cfg = norm_cfg |
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super(GARetinaHead, self).__init__(num_classes, in_channels, **kwargs) |
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def _init_layers(self): |
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"""Initialize layers of the head.""" |
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self.relu = nn.ReLU(inplace=True) |
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self.cls_convs = nn.ModuleList() |
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self.reg_convs = nn.ModuleList() |
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for i in range(self.stacked_convs): |
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chn = self.in_channels if i == 0 else self.feat_channels |
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self.cls_convs.append( |
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ConvModule( |
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chn, |
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self.feat_channels, |
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3, |
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stride=1, |
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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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self.reg_convs.append( |
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ConvModule( |
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chn, |
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self.feat_channels, |
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3, |
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stride=1, |
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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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self.conv_loc = nn.Conv2d(self.feat_channels, 1, 1) |
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self.conv_shape = nn.Conv2d(self.feat_channels, self.num_anchors * 2, |
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1) |
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self.feature_adaption_cls = FeatureAdaption( |
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self.feat_channels, |
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self.feat_channels, |
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kernel_size=3, |
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deform_groups=self.deform_groups) |
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self.feature_adaption_reg = FeatureAdaption( |
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self.feat_channels, |
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self.feat_channels, |
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kernel_size=3, |
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deform_groups=self.deform_groups) |
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self.retina_cls = MaskedConv2d( |
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self.feat_channels, |
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self.num_anchors * self.cls_out_channels, |
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3, |
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padding=1) |
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self.retina_reg = MaskedConv2d( |
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self.feat_channels, self.num_anchors * 4, 3, padding=1) |
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def init_weights(self): |
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"""Initialize weights of the layer.""" |
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for m in self.cls_convs: |
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normal_init(m.conv, std=0.01) |
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for m in self.reg_convs: |
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normal_init(m.conv, std=0.01) |
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self.feature_adaption_cls.init_weights() |
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self.feature_adaption_reg.init_weights() |
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bias_cls = bias_init_with_prob(0.01) |
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normal_init(self.conv_loc, std=0.01, bias=bias_cls) |
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normal_init(self.conv_shape, std=0.01) |
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normal_init(self.retina_cls, std=0.01, bias=bias_cls) |
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normal_init(self.retina_reg, std=0.01) |
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def forward_single(self, x): |
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"""Forward feature map of a single scale level.""" |
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cls_feat = x |
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reg_feat = x |
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for cls_conv in self.cls_convs: |
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cls_feat = cls_conv(cls_feat) |
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for reg_conv in self.reg_convs: |
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reg_feat = reg_conv(reg_feat) |
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loc_pred = self.conv_loc(cls_feat) |
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shape_pred = self.conv_shape(reg_feat) |
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cls_feat = self.feature_adaption_cls(cls_feat, shape_pred) |
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reg_feat = self.feature_adaption_reg(reg_feat, shape_pred) |
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if not self.training: |
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mask = loc_pred.sigmoid()[0] >= self.loc_filter_thr |
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else: |
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mask = None |
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cls_score = self.retina_cls(cls_feat, mask) |
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bbox_pred = self.retina_reg(reg_feat, mask) |
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return cls_score, bbox_pred, shape_pred, loc_pred |
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