[ITK] [ITK-users] 3D registration problem

[Bradley Lowekamp]

Hello,

This not the expected behavior for a good registration program.

Is your initialization good?

You haven't shared anything about the registration components you are using. Perhaps you scales are way off? How does the convergence look when monitoring the output?

Perhaps you have too many free parameters? Maybe you are trying to optimize an transform with too many parameters when you are not close. Perhaps you need to do a Translation + Rotation transform such as Euler or Versor first?

Hope that helps,
Brad

On Jul 15, 2014, at 5:26 AM, Iyas Hamdan <iyas.hamdan at gmail.com> wrote:

> Hello itk users,
> 
> I'm working on 3D image registration, currently I'm trying to register a CT volume to an MRI volume ( the two volumes have different sizes concerning the number of slices used to construct the 3D volume). 
> 
> I'm doing an affine registration using the mutual information as a metric, and I'm having problems registering those two volumes.
> 
> What I thiink the problem is, I have a different field of view between both volumes, so when I try to register the whole CT volume to the MRI one  the registration falis. However, when I deleted a dozen of slices from the CT volume ( so that I had the same field of view in both volumes) it works just fine and I was able to register the volumes. 
> 
> 
> And by "the registration failed" I meant it worked with no errors but the result was really bad! and that the registered volume was nothing like the fixed one, so if I try to find the difference between each two corresponding slices for example , they were not aligned at all! 
> 
> Is that normal that the registration doesnt work when I have a different field of view in each volume ? or should it deform one volume so that it corresponds to the other one even if they had two different fields of view ? 
> 
> Any help would be really appreciated, 
> 
> Thanks in advance, 
> 
> Iyas
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