[Insight-users] An overlap invariant mutual information metric

[Raghavendra Chandrashekara]

Luis Ibanez wrote:

>
> 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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>>
>
>
>
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Also what are the range of intensities in your images? When you set the 
padding value to -1, everything in the fixed image which has intensity 
<= -1 will be ignored.

Raghavendra