Source code for UM2N.model.MRN_fix

# Author: Chunyang Wang
# GitHub Username: acse-cw1722

import os
import sys

import torch
import torch.nn as nn
import torch.nn.functional as F
from torch_geometric.nn import GATv2Conv, MessagePassing

cur_dir = os.path.dirname(__file__)
sys.path.append(cur_dir)
from extractor import (  # noqa: E402
    GlobalFeatExtractor,
    LocalFeatExtractor,
)

__all__ = ["MRN_fix"]


class RecurrentGATConv(MessagePassing):
    """
    Implements a Recurrent Graph Attention Network (GAT) Convolution layer.

    Attributes:
        to_hidden (GATv2Conv): Graph Attention layer.
        to_coord (nn.Sequential): Output layer for coordinates.
        activation (nn.SELU): Activation function.
    """

    def __init__(self, coord_size=2, hidden_size=512, heads=6, concat=False):
        super(RecurrentGATConv, self).__init__()
        # GAT layer
        self.to_hidden = GATv2Conv(
            in_channels=coord_size + hidden_size,
            out_channels=hidden_size,
            heads=heads,
            concat=concat,
        )
        # output coord layer
        self.to_coord = nn.Sequential(
            nn.Linear(hidden_size, 2),
        )
        # activation function
        self.activation = nn.SELU()

    def forward(self, coord, hidden_state, edge_index):
        # find boundary
        self.find_boundary(coord)
        # Recurrent GAT
        in_feat = torch.cat((coord, hidden_state), dim=1)
        hidden = self.to_hidden(in_feat, edge_index)
        hidden = self.activation(hidden)
        output_coord = self.to_coord(hidden)
        # fix boundary
        self.fix_boundary(output_coord)
        return output_coord, hidden

    def find_boundary(self, in_data):
        self.upper_node_idx = in_data[:, 0] == 1
        self.down_node_idx = in_data[:, 0] == 0
        self.left_node_idx = in_data[:, 1] == 0
        self.right_node_idx = in_data[:, 1] == 1

    def fix_boundary(self, in_data):
        in_data[self.upper_node_idx, 0] = 1
        in_data[self.down_node_idx, 0] = 0
        in_data[self.left_node_idx, 1] = 0
        in_data[self.right_node_idx, 1] = 1


[docs] class MRN_fix(torch.nn.Module): """ Mesh Refinement Network (MRN) implementing global and local feature extraction and recurrent graph-based deformations. Attributes: num_loop (int): Number of loops for the recurrent layer. gfe_out_c (int): Output channels for global feature extractor. lfe_out_c (int): Output channels for local feature extractor. hidden_size (int): Size of the hidden layer. gfe (GlobalFeatExtractor): Global feature extractor. lfe (LocalFeatExtractor): Local feature extractor. lin (nn.Linear): Linear layer for feature transformation. deformer (RecurrentGATConv): GAT-based deformer block. """ def __init__(self, gfe_in_c=2, lfe_in_c=4, deform_in_c=7, num_loop=3): """ Initialize MRN. Args: gfe_in_c (int): Input channels for the global feature extractor. lfe_in_c (int): Input channels for the local feature extractor. deform_in_c (int): Input channels for the deformer block. num_loop (int): Number of loops for the recurrent layer. """ super().__init__() self.num_loop = num_loop self.gfe_out_c = 16 self.lfe_out_c = 16 self.hidden_size = 512 # set here # minus 2 because we are not using x,y coord (first 2 channels) self.all_feat_c = (deform_in_c - 2) + self.gfe_out_c + self.lfe_out_c self.gfe = GlobalFeatExtractor(in_c=gfe_in_c, out_c=self.gfe_out_c) self.lfe = LocalFeatExtractor(num_feat=lfe_in_c, out=self.lfe_out_c) # use a linear layer to transform the input feature to hidden # state size self.lin = nn.Linear(self.all_feat_c, self.hidden_size) self.deformer = RecurrentGATConv( coord_size=2, hidden_size=self.hidden_size, heads=6, concat=False ) # self.deformer = GATDeformerBlock(in_dim=self.deformer_in_feat)
[docs] def move(self, data, num_step=1): """ Move the mesh according to the deformation learned, with given number steps. Args: data (Data): Input data object containing mesh and feature info. num_step (int): Number of deformation steps. Returns: coord (Tensor): Deformed coordinates. """ coord = data.x[:, :2] # [num_nodes * batch_size, 2] conv_feat_in = data.conv_feat_fix # [batch_size, feat, 20, 20] mesh_feat = data.mesh_feat # [num_nodes * batch_size, 2] edge_idx = data.edge_index # [num_edges * batch_size, 2] node_num = data.node_num conv_feat = self.gfe(conv_feat_in) conv_feat = conv_feat.repeat_interleave(node_num.reshape(-1), dim=0) local_feat = self.lfe(mesh_feat, edge_idx) hidden_in = torch.cat([data.x[:, 2:], local_feat, conv_feat], dim=1) hidden = F.selu(self.lin(hidden_in)) # Recurrent GAT deform for i in range(num_step): coord, hidden = self.deformer(coord, hidden, edge_idx) return coord
[docs] def forward(self, data): """ Forward pass for MRN. Args: data (Data): Input data object containing mesh and feature info. Returns: coord (Tensor): Deformed coordinates. """ coord = data.x[:, :2] # [num_nodes * batch_size, 2] conv_feat_in = data.conv_feat # [batch_size, feat, grid, grid] mesh_feat = data.mesh_feat # [num_nodes * batch_size, 2] edge_idx = data.edge_index # [num_edges * batch_size, 2] node_num = data.node_num conv_feat = self.gfe(conv_feat_in) conv_feat = conv_feat.repeat_interleave(node_num.reshape(-1), dim=0) local_feat = self.lfe(mesh_feat, edge_idx) hidden_in = torch.cat([data.x[:, 2:], local_feat, conv_feat], dim=1) hidden = F.selu(self.lin(hidden_in)) # Recurrent GAT deform for i in range(self.num_loop): coord, hidden = self.deformer(coord, hidden, edge_idx) return coord