[Insight-users] Re: problems in Deformable 6

[Luis Ibanez]

Hi Dalal,

Dr. Lydia Ng, tracked this problem down and found that it is related
to the vnl_lbfgs optimizer not behaving properly when it is initialized
too close to the optimial value, more precisely, when it cannot produce
smaller values than the one obtained in the first iteration.

Lydia configured a new exmple by replacing the vnl_lbgfs optimizer with
the itkLBFGSBOptimizer. This new example has been commited as

    Insight/Examples/Registration/DeformableRegistration7.cxx


You will have to update your CVS checkout in order to get this new
example.


Please give it a try and let us know if you have further questions,


    Thanks


      Luis


-----------------------
Dalal, Dhaval wrote:

> Hi Luis 
> Some questions about Bsplines 
> 1) I ran Deforamableregistraion6.cxx, when i tried to register 2 same images
> in 2D( or even 3D) , I get the error "Mismatched between parameters and
> region size"
> 
> I have chnaged the gridSizeOnImage.Fill( 2 ), gridBorderSize.Fill( 3 ); 
> so that grid size is 5, so total number of parameters = (5*5)*2 = 50 
> Is it beacuse the transform is not getting 50 parameters?? 
> How can i check this..? 
> 2) Can you please tell me why do we need 4 nodes to compute any internal
> point in Bsplines? 
> Questions about LBFGSOptimizer 
> 1) The o/p of Deformableregistration6.cxx is in the form 
>   I(Iteration) NFN  FUNC GNORM STEPLENGTH. 
> What does each one stand for. I did read a paper 
> -R. H. Byrd, P. Lu and J. Nocedal. A Limited Memory Algorithm for Bound
> Constrained Optimization, (1995), SIAM Journal on Scientific and Statistical
> Computing , 16, 5, pp. 1190-1208. 
> 
> But still not clear what the ideal parameters should be?? 
> 2) Also I keep getting this error 
> IFLAG= -1. LINE SEARCH FAILED. SEE DOCUMENTATION OF ROUTINE MCSRCH ERROR 
> RETURN OF LINE SEARCH: INFO=4 POSSIBLE CAUSES: FUNCTION OR GRADIENT ARE 
> INCORRECT OR INCORRECT TOLERANCESvnl_lbfgs: ** EEEK ** 
> ExceptionObject caught ! 
> But when i increase the step length to  and 3 and keep the other parameters
> the same the error disappears? 
> Thanx 
> Dhaval 
> 
> 
>