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| """ Reperio-rPPG: 关系时序图神经网络用于远程生理测量 论文: arXiv:2511.05946 核心: Swin Transformer + R-GCN + Graph Transformer """
import torch import torch.nn as nn import torch.nn.functional as F from typing import Tuple
class ReperioRPPG(nn.Module): """ Reperio-rPPG 完整模型 Pipeline: 1. Swin Transformer 提取空间特征 2. Temporal Patch Shift (TPS) 时序交互 3. R-GCN 建模帧间周期关系 4. Graph Transformer 捕获长程周期依赖 5. 多尺度 POS + NDF 信号提取 """ def __init__(self, config: dict): super().__init__() self.spatial_encoder = SwinTransformer( img_size=config['img_size'], patch_size=config['patch_size'], in_chans=3, embed_dim=config['embed_dim'], depths=[2, 2, 6, 2], num_heads=[3, 6, 12, 24], window_size=7 ) self.tps = TemporalPatchShift( shift_ratio=config.get('tps_ratio', 0.1) ) self.rgcn = RelationalGCN( in_features=config['embed_dim'], hidden_features=config['hidden_dim'], num_layers=config.get('rgcn_layers', 3), num_relations=config.get('num_relations', 4) ) self.graph_transformer = GraphTransformer( in_features=config['hidden_dim'], d_model=config['hidden_dim'], nhead=config.get('nhead', 8), num_layers=config.get('gt_layers', 4), dim_feedforward=config['hidden_dim'] * 4 ) self.signal_head = nn.Sequential( nn.Linear(config['hidden_dim'], config['hidden_dim'] // 2), nn.GELU(), nn.Linear(config['hidden_dim'] // 2, 1) ) def forward(self, video: torch.Tensor) -> torch.Tensor: """ 前向传播 Args: video: 输入视频 (B, T, C, H, W) B=batch, T=时间帧数 Returns: bvp_signal: BVP 信号 (B, T) """ B, T, C, H, W = video.shape frames = video.view(B * T, C, H, W) spatial_features = self.spatial_encoder(frames) spatial_features = spatial_features.view(B, T, -1) shifted = self.tps(spatial_features) graph = self._build_temporal_graph(T, device=video.device) rgcn_out = self.rgcn(shifted, graph) gt_out = self.graph_transformer(rgcn_out, graph) bvp = self.signal_head(gt_out).squeeze(-1) return bvp def _build_temporal_graph(self, T: int, device: torch.device): """ 构建时序关系图 边类型: - relation 0: 相邻帧 (短期) - relation 1: 同周期帧 (intra-cycle) - relation 2: 跨周期帧 (inter-cycle) - relation 3: 长程依赖 """ edges = [] for i in range(T): if i > 0: edges.append([i, i-1, 0]) if i < T - 1: edges.append([i, i+1, 0]) for offset in [2, 4, 7, 10, 15, 20, 30]: j = i + offset if 0 <= j < T: rel = 1 if offset <= 15 else 2 edges.append([i, j, rel]) for offset in [45, 60, 90]: j = i + offset if 0 <= j < T: edges.append([i, j, 3]) edge_index = torch.tensor([[e[0], e[1]] for e in edges], device=device).t().contiguous() edge_type = torch.tensor([e[2] for e in edges], device=device) return {'edge_index': edge_index, 'edge_type': edge_type}
class TemporalPatchShift(nn.Module): """时序补丁位移 - 轻量级时序交互""" def __init__(self, shift_ratio: float = 0.1): super().__init__() self.shift_ratio = shift_ratio def forward(self, x: torch.Tensor) -> torch.Tensor: """ Args: x: (B, T, D) Returns: shifted: (B, T, D) """ shifted = x.clone() shift_dim = int(x.size(-1) * self.shift_ratio) if shift_dim > 0: shifted[:, 1:, :shift_dim] = x[:, :-1, :shift_dim] shifted[:, :-1, shift_dim:2*shift_dim] = x[:, 1:, shift_dim:2*shift_dim] return shifted
class SwinTransformer(nn.Module): """Swin Transformer 空间特征提取 (简化版)""" def __init__(self, **kwargs): super().__init__() self.proj = nn.Conv2d(3, kwargs.get('embed_dim', 96), kernel_size=4, stride=4) self.embed_dim = kwargs.get('embed_dim', 96) def forward(self, x): x = self.proj(x) x = x.flatten(2).transpose(1, 2) return x.mean(dim=1)
class RelationalGCN(nn.Module): """关系图卷积网络""" def __init__(self, in_features, hidden_features, num_layers, num_relations): super().__init__() self.layers = nn.ModuleList([ RGCNLayer(in_features if i == 0 else hidden_features, hidden_features, num_relations) for i in range(num_layers) ]) def forward(self, x, graph): for layer in self.layers: x = layer(x, graph) return x
class RGCNLayer(nn.Module): def __init__(self, in_f, out_f, num_rel): super().__init__() self.weight = nn.Parameter(torch.Tensor(num_rel, in_f, out_f)) nn.init.xavier_uniform_(self.weight) def forward(self, x, graph): out = torch.zeros_like(x) for r in range(self.weight.size(0)): mask = (graph['edge_type'] == r) if mask.any(): idx = graph['edge_index'][:, mask] msg = x[idx[0]] @ self.weight[r] out.scatter_add_(0, idx[1].unsqueeze(1).expand(-1, out.size(1)), msg) return F.normalize(out, dim=-1)
class GraphTransformer(nn.Module): """Graph Transformer for long-range periodic dependencies""" def __init__(self, in_features, d_model, nhead, num_layers, dim_feedforward): super().__init__() self.pos_embed = nn.Parameter(torch.randn(1, 300, d_model) * 0.02) encoder_layer = nn.TransformerEncoderLayer( d_model=d_model, nhead=nhead, dim_feedforward=dim_feedforward, batch_first=True, dropout=0.1 ) self.transformer = nn.TransformerEncoder(encoder_layer, num_layers) def forward(self, x, graph=None): T = x.size(1) x = x + self.pos_embed[:, :T] return self.transformer(x)
if __name__ == "__main__": config = { 'img_size': 224, 'patch_size': 4, 'embed_dim': 96, 'hidden_dim': 256, 'rgcn_layers': 3, 'num_relations': 4, 'nhead': 8, 'gt_layers': 4, 'tps_ratio': 0.1 } model = ReperioRPPG(config) video = torch.randn(2, 150, 3, 224, 224) bvp = model(video) print(f"Input shape: {video.shape}") print(f"BVP output shape: {bvp.shape}") print(f"Parameters: {sum(p.numel() for p in model.parameters()):,}")
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