[Insight-users] Offset CenteredTransformInitializer

[Lars Nygard]

Hi Luis,

My program is working as expected but I have some questions about
setting the center. As said I get the best results when I use the geometric
center. This is not very surprising I just figured because this is also the center
I used when creating the registration problems.
The momentsOn calculates a center which is far off.
My question is how do you determine the center in a real registration problem?
Is there a unique point around which rotatations occur?  
Is it possible to constrain the registration problem with different rotation
axis?
greets,
Lars

----- Original Message ----
From: Luis Ibanez <luis.ibanez at kitware.com>
To: Lars Nygard <lnygard at yahoo.com>
Cc: insight-users at itk.org
Sent: Tuesday, August 28, 2007 1:48:54 PM
Subject: Re: [Insight-users] Offset CenteredTransformInitializer


Hi Lars,

    Please help us solve the mystery.

Share with use the following information:

1) Coordinates of the Fixed image origin
2) Fixed image spacing
3) Fixed image number of pixels
4) Coordinates of the Moving image origin
5) Moving image spacing
6) Moving image number of pixels

7) Center of rotation computed by the
    CenteredTransformInitializer.


Also, notes that the MomentsOn will set
the center of rotation in the center of
mass of your pixel intensity values.

    What is the content of your image ?
      a brain ? is it centered ?
    or is it a microscopy image with a huge
      organelle on the corner of the image ?


With this information at hand we shoul be
able to figure out what is going on in your
application.



    Thanks


       Luis


------------------
Lars Nygard wrote:
> Hi,
> 
> Im getting wrong results using the CenteredTransformInitializer in both
> MomentsOn and GeometryOn. When I manually set the center of the transform
> as the center of the fixed image (origin + Spacing*Dimension/2) everything goes OK. 
> But when I use the  initializer Im ending way besides the correct registration result.
> I was wondering, is the Offset used when the CenteredTransformInitializer calculates
> the center (in GeometryOn)??
> And does anyone can explain why Im getting good results with setting the center manually
> while the results aren't good when using MomentsOn??
> Thanks for any feedback,
> greets,
> Lars
> 
> 
> 
> 
>       
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