[Insight-users] FEM Registration

[Brian]

Mike - thank you for your interest in ITK and FEM.  we would like to help
with your problem, but need to know more about the parameters you are
using for the registration.  the default parameters may not be good for
the problem you have.  it would be very helpful if you included a copy of
your control file.  note that it is also useful to normalize the images by
using histogram matching.  hope to hear from you soon, Brian



On Thu, 24 Apr 2003, Mike Bristow wrote:

>
> Hi,
>
> I am a new user of ITK and I have been trying to implement the FEM
> deformable registration examples on some MR data without much luck. The
> DeformableRegistration1 example seems to run OK on the sample
> RatLungSlice data but it is difficult to see the effect. I have tried
> running the same program with the same parameters on some 512x512
> proton density-weighted MR images (to try to register two different
> patients). It seems as though part of the image moves but another part
> doesn't. I tried increasing the number of iterations (25 to 100) with
> pretty much the same result. As well, I tried deforming the same data
> with the FEM/FEMImageRegLMEx example application that implements a
> multiresolution scheme using the default parameters given and the
> results were worse (one local area gets deformed badly with no effect
> anywhere else). Does anyone have some documentation/articles/tips that
> might help me out with selecting better parameters?
>
> I'm also having trouble getting the SquaredDifference of the results of
> the RatLungSlice data. It seems as though I'm having problems because
> the FEM filter writes the output as 32-bit. Rescaling and casting to
> float/internal, diffing, rescaling and then casting to short or long
> for output doesn't seem to work. When I output the 32-bit image as
> short or long it appears corrupted and I get the following error when I
> try to write the diffed image. Any ideas?
>
> itk::ExceptionObject (0x26dab0)
> Location: "Unknown"
> File: /usr/local/include/InsightToolkit/IO/itkImageFileWriter.txx
> Line: 119
> Description: itk::ERROR: ImageFileWriter(0x26c000): No ImageIO set, or
> none could be created.
>
> Thanks,
> Mike Bristow
>
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