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| import torch import torch.nn as nn import torch.nn.functional as F
class FeatureFusionModule(nn.Module): """ 特征级融合模块 论文Section 4.2: 在特征空间进行融合 优势: 保留中间表示,端到端训练 """ def __init__(self, radar_dim: int = 64, camera_dim: int = 256, fused_dim: int = 128): super().__init__() self.radar_encoder = nn.Sequential( nn.Conv2d(radar_dim, 128, kernel_size=3, padding=1), nn.BatchNorm2d(128), nn.ReLU(inplace=True), nn.Conv2d(128, fused_dim, kernel_size=3, padding=1), nn.BatchNorm2d(fused_dim), nn.ReLU(inplace=True) ) self.camera_encoder = nn.Sequential( nn.Conv2d(camera_dim, 256, kernel_size=3, padding=1), nn.BatchNorm2d(256), nn.ReLU(inplace=True), nn.Conv2d(256, fused_dim, kernel_size=3, padding=1), nn.BatchNorm2d(fused_dim), nn.ReLU(inplace=True) ) self.fusion_conv = nn.Sequential( nn.Conv2d(fused_dim * 2, fused_dim, kernel_size=3, padding=1), nn.BatchNorm2d(fused_dim), nn.ReLU(inplace=True), nn.Conv2d(fused_dim, fused_dim, kernel_size=3, padding=1), nn.BatchNorm2d(fused_dim), nn.ReLU(inplace=True) ) self.attention = ChannelAttention(fused_dim * 2) def forward(self, radar_feat: torch.Tensor, camera_feat: torch.Tensor) -> torch.Tensor: """ 前向融合 Args: radar_feat: 雷达特征 (B, C_r, H, W) camera_feat: 相机特征 (B, C_c, H', W') Returns: 融合特征 (B, fused_dim, H, W) """ radar_encoded = self.radar_encoder(radar_feat) camera_encoded = self.camera_encoder(camera_feat) if radar_encoded.shape[2:] != camera_encoded.shape[2:]: camera_encoded = F.interpolate( camera_encoded, size=radar_encoded.shape[2:], mode='bilinear', align_corners=False ) concat_feat = torch.cat([radar_encoded, camera_encoded], dim=1) attended_feat = self.attention(concat_feat) fused_feat = self.fusion_conv(attended_feat) return fused_feat
class ChannelAttention(nn.Module): """通道注意力模块""" def __init__(self, channels: int, reduction: int = 16): super().__init__() self.avg_pool = nn.AdaptiveAvgPool2d(1) self.max_pool = nn.AdaptiveMaxPool2d(1) self.fc = nn.Sequential( nn.Linear(channels, channels // reduction, bias=False), nn.ReLU(inplace=True), nn.Linear(channels // reduction, channels, bias=False) ) self.sigmoid = nn.Sigmoid() def forward(self, x: torch.Tensor) -> torch.Tensor: B, C, _, _ = x.size() avg_out = self.fc(self.avg_pool(x).view(B, C)) max_out = self.fc(self.max_pool(x).view(B, C)) attention = self.sigmoid(avg_out + max_out).view(B, C, 1, 1) return x * attention
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