[Insight-users] itkCenteredRigid2DTransform registration optimization problems

[Felix Bollenbeck]

Hi Gabriele,

ok, that is some kind of random search, right? - I have to read the 
paper for understanding.

Was it difficult to tune the parameters? I am not using mutual 
information metric, but I will try it out.

I guess I will have to anneal 'epsilon' when going to finer scales. can 
you comment on your choice of parameters?

Thanks for your time!

FElix.




gabri wrote:
> Hi Felix,
> I've had a lot of problems with the regularstepgrdient descent , finally
> I switch all my code to use the OnePlusOneEvolutionaryOptimizer that is
> relly well suited for the MattesMutulaInformationMetric .
> Using that classes , after finding the correct parameters tuning for the
> optimizer,all problems due to miallignement disappers in my case (MRI
> AffineRegistration) .
>
> Best Reguards
>
> Gabriele
>
> Felix Bollenbeck ha scritto:
>   
>> Hi ITKusers
>>
>> Im using the itkCenteredRigid2DTransform to register a stack of
>> light-microscopy slice images containing sectionend objects in masked
>> background within the image-pyramid framework of ITK.
>>
>> I have a question regarding the transformtype for registration of
>> image pairs:
>>
>> objects in the images I use have a kind of symmetry axes, they are
>> 'similar' on both sides but not the 'same'. The problem is, that
>> sometimes the optimizer gets stuck in a local optimum representing the
>> alignment of two images where the moving images is flipped along this
>> axis-can I make myself clear?
>>
>> The problem is- that on broader scales, this 'similarity' turns out to
>> be more less 'same', which causes the parameters to remain in this
>> 'valley' in the subsequent fine optimization on smaller scales.
>>
>> starting with a finer resolution ends up in bad convergence, or bad
>> overall results.
>>
>> I tried to tune stepwidths, optimizer scales etc. but i couldnt find
>> any overall tendency, due to my little detailed knowledge on the
>> optmizer (regularstepdescent).
>>
>> Can anybody suggest a method how to optimize the rotation angle more
>> carefully?
>>
>> Regards&TIA,
>>
>> Felix.
>>
>>
>>
>>     
>
>
>   


-- 
Felix Bollenbeck     		Email: bollen at ipk-gatersleben.de
Pattern Recognition Group       Phone: +49 (0)39482 5344
Leibniz Institute of Plant 	Fax  : +49 (0)39482 5137
Genetics and Crop Plant Research
Correnstr.3 	                http://www.ipk-gatersleben.de
06466 Gatersleben,Germany