[Insight-users] Registration with ITK and a MicroScribe Digitizer

[Luis Ibanez]

Hi Dirk,

That sounds like a very interesting problem.

Here are some comments:

1) Converting VTK point set to ITK Point Set:

    Option A:

    Once you read the STL file with VTK you can
    write it down as a VTK file and read it with
    the new class:

         Insight/Code/Review
            itkVTKPolyDataReader.h
            itkVTKPolyDataReader.txx


    Option B:

    You can convert the VTK polydata into an ITK
    point set by using the code in:

      InsightApplications/Auxiliary/vtk
                   vtkPolyDataToITKMesh.cxx


2) You don't really need to preprocess the point
    set before performing the registration,
    unless you have so many points that it is
    worth to subsample the point set.  If you
    have less than 20,000 points and a decent
    computer, then you shouldn't need to subsample.

    It is a matter of balancing computation time
    and registration precision and stability.



3) Nope,
    there is not a way of reading an STL file
    directly into ITK.





   Regards,


      Luis



======================
Dirk Hollstein wrote:
> Hello,
> 
> we want to register data acquired from a microscribe digitizer with  
> data from an stl-file (stereo-lithography). We collect data by  sampling 
> surface points on a real world object with the digitizer.  The stl-file 
> describes this real world object (a cuboid).
> 
> We did look at the examples for PointSetToImageRegistrationTest_1 and  
> ModelToImageRegistration2, still we have several problems we could  not 
> solve:
> 
> - How can we extract the necessary PointSet data from the stl-file  for 
> registration (assuming PointSet is the way to go)? Currently we  read 
> the stl-file with VTK.
> 
> - How can we get this data into ITK for registration?
> 
> - Do we have to process the stl file before we are able to register  it, 
> e.g. by applying a certain filter to it?
> 
> - Is there a way to read an STL-file directly into ITK?
> 
> Any help is appreciated, since we do not know how to proceed from here.
> 
> Thanks a lot in advance,
> Dirk
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