Source code for UM2N.model.MRN_LTE
# Author: Chunyang Wang
# GitHub Username: acse-cw1722
# Modified by Mingrui Zhang
import os
import sys
import torch
import torch.nn as nn
import torch.nn.functional as F
cur_dir = os.path.dirname(__file__)
sys.path.append(cur_dir)
from deformer import ( # noqa: E402
RecurrentGATConv,
)
from extractor import ( # noqa: E402
GlobalFeatExtractor,
)
from transformer_model import TransformerModel
__all__ = ["MRNLocalTransformerEncoder"]
[docs]
class MRNLocalTransformerEncoder(torch.nn.Module):
"""
Mesh Refinement Network (MRN) implementing global and local feature
extraction and recurrent graph-based deformations.
The global feature extraction is performed by a transformer.
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)
self.transformer_in_dim = 4
self.transformer_out_dim = 16
self.transformer_encoder = TransformerModel(
input_dim=self.transformer_in_dim,
embed_dim=64,
output_dim=self.transformer_out_dim,
num_heads=4,
num_layers=1,
)
# 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)
def _forward(self, data):
"""
Forward pass for MRN.
Args:
data (Data): Input data object containing mesh and feature info.
Returns:
coord (Tensor): Deformed coordinates.
"""
conv_feat_in = data.conv_feat # [batch_size, feat, grid, grid]
batch_size = conv_feat_in.shape[0]
mesh_feat = data.mesh_feat # [num_nodes * batch_size, 4]
node_num = data.node_num
conv_feat = self.gfe(conv_feat_in)
conv_feat = conv_feat.repeat_interleave(node_num.reshape(-1), dim=0)
feat_dim = mesh_feat.shape[-1]
# mesh_feat [coord_x, coord_y, u, hessian_norm]
# Here we select the u and hessian_norm for global feature extraction
local_feat = self.transformer_encoder(
mesh_feat.reshape(batch_size, -1, feat_dim)
)
local_feat = local_feat.reshape(-1, self.transformer_out_dim)
hidden_in = torch.cat([data.x[:, 2:], local_feat, conv_feat], dim=1)
hidden = F.selu(self.lin(hidden_in))
return hidden
[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]
edge_idx = data.edge_index
hidden = self._forward(data)
# 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]
edge_idx = data.edge_index
hidden = self._forward(data)
# Recurrent GAT deform
for i in range(self.num_loop):
coord, hidden = self.deformer(coord, hidden, edge_idx)
return coord