[vtkusers] How to write multiple surfaces into a single STL file?

[Huiqun Zhou]

  Jiye,

  You can use multi actors, each for one iso-surface extracted from your
data with vtkContourFilter or
  vtkMarchingCubes, and then you can create multi renderers for your actors,
one for each. The important
  point is to create a render window with sufficient size and divide the
window into viewports, just one
  for each actor. In this way, you can pick and elements on any iso-surfaces
you created, and you can
  easily, I think and I never tried myself, save you data together because
everything is in only one render
  window.

  Cheers!

  Huiqun Zhou

  ----- Original Message ----- 
  From: "An Jiye" <an_jiye at hotmail.com>
  To: <goodwin.lawlor at ucd.ie>
  Cc: <vtkusers at vtk.org>
  Sent: Friday, February 20, 2004 9:05 AM
  Subject: Re: [vtkusers] How to write multiple surfaces into a single STL
file?


  > > You can:
  > > 1. Use vtkAppendPolyData to append all the outputs from multiple
  > > vtkContourFilter's into one PolyData
  > > 2. Just use one instance of vtkContourFilter (and one vtkActor etc) in
the
  > > first place, extracting all the contours by setting multiple contour
  > values
  > > in the one filter
  > >
  > > HTH
  > >
  > > Goodwin
  >
  > Thank your for the hint£¬Goodwin. Definitely, this will help me very
much.
  >
  > I think maybe the second method is easily to understand, anyway all the
  > surfaces come from the same data set.
  >
  > But in my application, I will pick point from EACH surface after
rendering.
  > As I understand, actor is the object of vtk picking. So I can not pick
  > points from some inside surfaces if all of them were extracted and
rendered
  > by a single actor. Each of these inside surfaces are a part of the actor
and
  > they were coverd by some other parts. I can not separate them.
  >
  > Considering this point, I will make each actor represents a surface. No
  > matter which surface I want to pick on, I can set other
actors'(surfaces)
  > PickableOff, or even VisibilityOff.
  >
  > So my visualization pipeline will be like this:
  >
  > vtkImageData -> vtkContourFilter(value 1) -> vtkPolyDataMapper ->
vtkActor
  > vtkImageData -> vtkContourFilter(value 2) -> vtkPolyDataMapper ->
vtkActor
  > .. ...
  >
  > When rendering, add all these actors into one render window. And the
picking
  > function can be applied to each actor.
  >
  > As for saveing the rendering result into STL file, I will remove all the
  > actors and data mappers. Instead, use vtkAppendPolyData::AddInput() to
  > appent all the contour filters' outpus into a single polygonal dataset.
The
  > remaining parts of the wring pipline would be:
  >
  > vtkAppendPolyData -> vtkTriangleFilter -> vtkSTLWriter
  >
  > Did I fully understand you?
  >
  > An Jiye
  >
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