[vmtk-users] 3d ustructured mesh of an artery - how to convert file formats?

[Emilie S. <emi...@uc...>]

Dear vmtk users,

 I'd like to convert a file from vtk legacy format to stl format. I tried
to use the following command:

  vmtksurfacewriter -ifile my_input.vtk -ofile surface.stl

The input file is a vtk 'unstructured grid'. When I run the above command,
I get the following error:

Creating vmtkSurfaceWriter instance.
Automatic piping vmtksurfacewriter
Parsing options vmtksurfacewriter
    SurfaceInputFileName = my_input.vtk
    OutputFileName = surface.stl
Explicit piping vmtksurfacewriter
Input vmtksurfacewriter members:
    Id = 0
    Disabled = 0
    Surface = None
    SurfaceInputFileName = my_input.vtk
    Format =
    GuessFormat = 1
    CellData = 0
    OutputFileName = surface.stl
    OutputFileName = surface.stl
Reading VTK surface file.
ERROR: In /home/esauvage/opensource/VTK/IO/vtkPolyDataReader.cxx, line 137
vtkPolyDataReader (0x89a9630): Cannot read dataset type: unstructured_grid

Executing vmtksurfacewriter ...
Writing STL surface file.
ERROR: In /home/esauvage/opensource/VTK/IO/vtkSTLWriter.cxx, line 48
vtkSTLWriter (0x8bd5ba8): No data to write!

Done executing vmtksurfacewriter.
Output vmtksurfacewriter members:
    Id = 0

>From the first error message it looks like vmtksurfacewriter calls
vtkPolyDataReader. I guess that means that I need to have my input file
saved as vtk 'polydata'. Is this right?
I also don't know what's the easiest way of converting
UNSTRUCTURED_GRID->POLYDATA in vtk. Could someone be so kind and give me a
hint?

I'm sorry if the answer is obvious. I'm a vmtk beginner and googling
didn't help much.

Best regards,

 Emilie Sauvage