graphlow.TensorMesh.extract_surface#

TensorMesh.extract_surface(*, keep_graph: bool = True) → TensorMesh[T]#

Extract the boundary surface as a new 2D mesh.

The returned surface mesh reuses this mesh’s point tensor, so autograd remains connected to the original volume points.

The mapping from surface points to parent volume points is available via surface.parent_point_ids and related gather/scatter helpers.

Parameters:
keep_graphbool, default=True

If True, surface points (and transferred point_data) are views into the original backend tensors, preserving the computation graph. If False, the returned tensors are detached, so gradients do not flow back to this mesh.

Returns:
TensorMesh[T]

Surface mesh (2D boundary cells) with:

  • points: subset of the volume points,

  • point_data: subset of the volume point_data,

  • parent_point_map: metadata mapping surface points back to parent volume points.