[vtkusers] 3D Radon transform

[David Gobbi]

Hi Zamir,

If you are set on doing things with Fourier transforms, you can get your
various projection angles by using vtkImageReslice in the Fourier domain to
extract the "central slice" that corresponds to the projection.

Or, if you are fine with skipping Fourier space altogether, I have a
projection filter for VTK,
http://github.com/dgobbi/VTK/commit/e7f87237
It only does projections along X, Y, or Z so it has to be preceded by
vtkImageReslice if you require arbitrary angles.

But even that will not give you a sinogram, it will just give a bunch of
images corresponding to the various projections.  You'd still have to stack
the images together, e.g. with vtkImageAppend.  I honestly can't say whether
it would be better to do this with a VTK pipeline or whether it would be
better to write a dedicated Radon transform filter.

  David




On Fri, Dec 3, 2010 at 2:04 PM, Zamir Khan <zkhan at modusmed.com> wrote:

> I am interested in computing the 3D Radon transform of a data-set. This is
> as I understand it, inverse backprojection, and gives all the 2d projections
> (given angles phi, theta, psi) through a 3d image. Before re-inventing the
> wheel, I wanted to make sure I’m not missing any potentially re-usable
> elements of VTK for this problem. There is not a direct Radon transform in
> VTK, but in this paper (
> http://bioinformatics.oxfordjournals.org/content/14/2/212.abstract), the
> computation is elegantly broken down to a few steps that involve 2-D and 1-D
> FFTs, conversion to polar coordinates, and 3-d matrix transposition.
>
>
>
> My question to the VTK community (especially those more familiar with the
> API) is if there are any classes within VTK that would be useful in tackling
> this problem. Of course, if you have suggestions outside of VTK, those would
> be welcome as well. Unfortunately, based on my search so far, it seems that
> this will be something that needs to be written nearly from scratch.
>
>
>
> Thanks in advance for any insights,
>
> Zamir
>
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