[Insight-users] isosurface normals in itk???

[Luis Ibanez]

Hi Hrishi,

You could do this in ITK by using:


a) ImageSeriesReader

    See the example:

    Insight/Examples/IO/
      DicomSeriesReadImageWrite2.cxx


b) A segmentationn filter

    for example:

     ConfidenceConnected
     ThresholdConnected

   See the ITK Software Guide for details
   on them. You will find examples on their
   use in

   Insight/Examples/Segmentation


c) From the segmented image, you can
    extract a surface by using


       itkBinaryMask3DMeshSource


d) There is no filter in ITK for just
    computing the normals to a surface
    but you may find code to copy/paste
    from the following filters

    itkDeformableMesh3DFilter.txx

    that computes normals internally.

    Note that the method uses only
    the immediate neighbor triangles,
    so the normals may be noisy (not
    parallel to neighbors).

    If you find them too noisy, you
    may want to insert the AntiAlias
    image filter between the output
    of the segmentation filter and
    the input to the BinaryMask3DMeshSource.
    (I will suggest you to do that).


Note that because there are several steps
in this pipeline, you want to go progressively
with it, and to check every intermediate result
before you move into the next step.



   Regards,


       Luis


--------------
Hrishi wrote:
> I have CT image volume. I have the series in DICOM format. I have to 
> extract a surface which represents bone from the volume.
> Then I want to triangulate the surface and get normals to the triangle 
> at every vertex. 
> I dont have to necessarily visualize isosurface. My only requirement is 
> isonormals. Can I do this in ITK or I will have to use VTK functions?
> I just started using ITK 2 weeks ago. I downloaded VTK too. I saw an 
> example of isosurface extraction in the examples folder in vtk. But 
> still I am not even comfortable to use ITK so far I dont want to jump to 
> VTK unless it is absolutely necessary.
> 
> Thanks
> 
> Hrishi
> 
> 
> 
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