[Insight-users] Problem with 2D Registration (local minima)

[Manuel David Tabas Calle]

Hello ITK,

 

I´m working with ITK to do registration of 2D images and I think I reach a local minima that makes a poor registration.

 

I´m using 2D images 2000x2000 pixels in what the moving image needs a rotation and a translation. So I reproduced the ImageRegistration6.cxx to do that. But the result I got is not good enough so I think that the MeanSquares metric reaches a local minima. The value of the metric is about 4000 (aprox.), and I run a test using as input parameters the optimal ones (that is, the result I think i should obtain) and the metric returns a value of 2500 (aprox.). 

 

The framework I use is:

  

   itkImageRegistrationMethod

   itkMeanSquaresImageToImageMetric

   itkLinearInterpolateImageFunction

   itkRegularStepGradientDescentOptimizer

   itkCenteredRigid2DTransform

 

And the parameters of my registration are:

 

const double translationScale = 1.0 / 1000.0;

optimizerScales[0] = 1.0;

optimizerScales[1] = translationScale;

optimizerScales[2] = translationScale;

optimizerScales[3] = translationScale;

optimizerScales[4] = translationScale;

 

optimizer->SetMaximumStepLength( 0.1 );

optimizer->SetMinimumStepLength( 0.001 );

optimizer->SetNumberOfIterations( 200 );

 

 

The scales are well defined and I tried to vary the parameters of the optimizer but the results were similar, so I don´t know what to do next. Any idea??

 

Thank you in advance, I hope you can have more ideas to try.

 

 

 

Manuel.

 

 

 

 
 		 	   		  
_________________________________________________________________
Infórmate, mantente en contacto y encuéntralo todo, a la vez. Con la nueva Toolbar de MSN  nunca has tenido tantas ventajas en tan poco espacio. 
http://toolbar.es.msn.com/
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.itk.org/pipermail/insight-users/attachments/20091021/7ed60d3e/attachment.htm>