Mesh volume - will throw a VTK error/warning if not a closed surface

        Returns
        -------
        volume : float
            Total volume of the mesh.

def volume(self):
        """
        Mesh volume - will throw a VTK error/warning if not a closed surface

        Returns
        -------
        volume : float
            Total volume of the mesh.

        """
        mprop = vtk.vtkMassProperties()
        mprop.SetInputData(self.tri_filter())
        return mprop.GetVolume()