[Insight-users] Image registration error

[Daniel Mace]

Eric,

The only way that exception could be thrown is if the pixel count for a 
particular iteration through the GetValue() method equaled 0.  It could 
be that for one reason or another, your previous inputs are not updating 
their Region areas like they should.  Before setting your moving and 
fixed images, try calling the ->Update() method on each one.

BTW, what kind of transform are you using, and what are your initial 
parameters for it?

Cheers,
Dan

Eric John wrote:
>
> Hi Dan, I did have experience with rotating images out of view, but 
> the rotated image is basically centered in both of my image 
> viewers.....I even looked at the header file, but don't see anything 
> that would indicate offsets, etc. Any suggestions, I would like to use 
> the pre-rotated image for preproccesing reasons?
>
> Thanks alot,
>
> Eric 
>
>     From:  /Daniel Mace <dlm19 at duke.edu>/
>     To:  /Eric John <elviscrazyfingers at hotmail.com>/
>     CC:  /insight-users at itk.org/
>     Subject:  /Re: [Insight-users] Image registration error/
>     Date:  /Thu, 11 Jan 2007 16:11:44 -0500/
>     >Eric,
>     >
>     >It means that your moving image doesn't line up with any pixels in
>     >your fixed image (i.e. you've rotated it completely off of the map).
>     >  You need to adjust your starting parameters so that at least some
>     >of the pixels are lined up.
>     >
>     >It's probably easiest just to set your initial parameters to the
>     >rotation instead of rotating beforehand (unless you are trying to
>     >preprocess all your images for normalization).  Don't forget that in
>     >order to rotate your moving image by 90 degrees you actually have to
>     >set your initial rotation parameter to -90 (or -1.57, as it's in
>     >radians).   The transformation parameters are all in terms of the
>     >fixed image, and not the moving image (e.g. a scale of 0.1 actually
>     >magnifies your moving image by 10, and a x translation of 50
>     >actually moves your moving image -50 units).  This caused me a bit
>     >of confusion  starting out.
>     >
>     >Cheers,
>     >Dan
>     >
>     >Eric John wrote:
>     >>
>     >>Hello all, I am trying to register two 3-d MRI images (.mhd). The
>     >>moving image was previously rotated 90 degrees so that both images
>     >>would be in the same orientation for ease of registration. Before
>     >>rotating, it caused no error, now I get this error:
>     >>
>     >>ExceptionObject caught !
>     >>
>     >>itk::ExceptionObject (012AFBA4)
>     >>Location: "unknown"
>     >>File:
>     >>C:\InsightToolkit-2.8.1\Code\Algorithms\itkMeanSquaresImageToImageMetric.t
>     >>xx
>     >>Line: 369
>     >>Description: itk::ERROR: MeanSquaresImageToImageMetric(01805120):
>     >>All the points
>     >>  mapped to outside of the moving image
>     >>
>     >>Any explanation for this? btw, this is one of the registration
>     >>examples: ImageRegistration8
>     >>  Thanks,
>     >>Eric
>     >>
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