[Insight-users] itkCenteredRigid2DTransform registration optimization problems

[Felix Bollenbeck]

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