[Insight-users] An overlap invariant mutual information metric

[Luis Ibanez]

Hi Jessica,

This error message indicates that your Transform is
so far off that the moving image is mapped quite far
from the fixed image. As a result there is no overlap
at all between the images and therefore the metric
cannot compute the similarity of the matching.

Here are some suggestions:

1) Very important: create an itk::Command class and
    connect it as observer to the optimizer. You will
    find multiple examples on the SoftwareGuide on how
    to do this.  Having an observer will provide you
    feedback on the evolution of the transform as the
    optimization process is running.

        http://www . itk . org/ItkSoftwareGuide . pdf

2) Make sure that origin and spacing on both of your
    images are assigned correctly. They don't have to
    be the same, just check that the values correspond
    to the actual physical range.

3) Check how you are initializing the transform.
    It may be that from the very beginning your transform
    is far off. A simple way to start is to set up the
    transform to the identy by using the SetIdentity() method.


Please let us know if you have further questions,


Thanks



   Luis



------------------------
Jessica de Ryk wrote:

> I have still been trying to implement the NormalizedMutualInformationMetric.
> As it is, my code generates a run time error that states 'all the points
> mapped to outside of the moving image'
> I am using;
> TranslationTransform
> RegularStepGradientOptimizer
> LinearInterpolateImageFunction
> 
>   unsigned int nBins = 50;
>   MetricType::HistogramType::SizeType histSize;
>   histSize[0] = nBins;
>   histSize[1] = nBins;
>   metric->SetHistogramSize(histSize);
> 
>   metric->SetPaddingValue(-1);
>   metric->UsePaddingValue();
> 
> I have set optimizer->MaximizeOn();
>                 optimizer->SetMaximumStepLength(2.0)
>                 optimizer->SetMinimumStepLength(0.005)
>                 optimizer->SetNumberOfIterations(200)
> 
> I have set the
> Any ideas what could be causing this error?
> Thanks
> Jess
> 
> 
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