[ITK-users] What is an accepted duration of a 3D registration? Should I expect the MSE to "converge" to 0?

[Marina Bendersky]

I guess I'm using the debug mode ... (not using Visual Studio).

Thanks so much for your help!
Marina

On Mon, Sep 21, 2015 at 4:53 AM, Matias Montroull <matimontg at gmail.com> wrote:
> Hi Marina,
> Did you compile in release mode or debug?
> Regards,
>
> Matias
>
> On Sep 14, 2015 7:56 PM, "Marina Bendersky" <marina.bendersky at gmail.com>
> wrote:
>>
>> Hello,
>>
>> I'm doing a 3D registration of 2 CT volumes (the fixed one contains
>> 131 dicom images and the moving has 145 dicom images).
>>
>> I first converted each dicom series into one mha volume, using the
>> example DicomSeriesReadImageWrite2.cxx and then, I do the registration
>> following the example imageRegistration20.cxx. Below are the main
>> registration components and parameters (other parameters had their
>> default values):
>>
>> typedef itk::AffineTransform< double, Dimension  >  TransformType;
>> typedef itk::RegularStepGradientDescentOptimizer     OptimizerType;
>> typedef itk::MeanSquaresImageToImageMetric< FixedImageType,
>> MovingImageType >  MetricType;
>> typedef itk::LinearInterpolateImageFunction< MovingImageType, double >
>>  InterpolatorType;
>>
>> double translationScale = 1.0 / 1000.0;
>> optimizer->SetMaximumStepLength( 0.05 );
>> optimizer->SetMinimumStepLength( 0.01 );
>>
>>
>> This 3D registration runs on a MacBookPro laptop for 5.5 hours, so I
>> was wondering, is this "normal"? How long should a 3D registration
>> take?
>>
>> Also, the MSE metric keeps decreasing (though incrementally) even
>> after 300 iterations (plot attached), and there are oscillations
>> around the iteration 150 (I ran this twice and both times I get this
>> plot!) - why could this be?
>>
>> Should I expect the MSE metric to converge to 0, or something closer
>> to 0 (instead of the current values, in the ninety thousands...)?
>>
>> Thank you for your help,
>> Marina
>>
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