[Insight-users] image orientation and registration, current status ?

[Rupert Brooks]

Yes the OrientedImage derivative problem is troublesome.

If your images are small enough, and your transformation is simple
enough, the easiest way around it is to use an optimizer that does not
need derivatives.  Powell's would probably be my choice.  This
approach gets slow for any sort of complex problem, unfortunately.

I wrote an Insight Journal paper on the topic that may interest you,
with some code.  I use the classes in it on a daily basis, so i am
quite confident in them.  However, you would have to modify the code
of your metrics.
http://insight-journal.org/midas/handle.php?handle=1926/1293

I've also been poring over the code for the multithreaded/optimized
metrics (it is now in the Review directory in CVS)  It seems to have a
general gradient method where the problem probably COULD be corrected.
(http://hdl.handle.net/1926/566)

Please understand, i am just reading, not developing those
multithreaded metrics, so I cannot say for sure if they correct this
problem or not. Perhaps someone working on that project can advise.

Cheers,
Rupert B.




> Date: Fri, 1 Feb 2008 08:17:34 -0500
> From: "Bill Lorensen" <bill.lorensen at gmail.com>
> Subject: Re: [Insight-users] image orientation and registration,
>        current status ?
> To: "Stefan Klein" <stefan at isi.uu.nl>
> Cc: insight-users at itk.org
> Message-ID:
>        <4db4735c0802010517pc6f45bdw7506c29200b1d64d at mail.gmail.com>
> Content-Type: text/plain; charset="iso-8859-1"
>
> The gradient problem is being corrected for itkOrientedImage. See:
> http://public.kitware.com/Bug/view.php?id=5081
>
> If you need to take into account orientation, you should use
> itkOrientedImage. Another option is to use itkImage and reorient the series
> with itkOrientImageFilter so that both series have the same orientation.
>
> Bill

-- 
--------------------------------------------------------------
Rupert Brooks
McGill Centre for Intelligent Machines (www.cim.mcgill.ca)
Ph.D Student, Electrical and Computer Engineering
http://www.cyberus.ca/~rbrooks