[Insight-users] parameters for a 1+1 evolutionary optimizer

[Denis Nikitenko]

Hi Luis,

Thank you for the quick reply. I just hope my message wasn't _too_ detailed - I
wanted to give a clear statement of my problem and hopefuly did not go overboard.

Now, to answer your questions:

> 1) How are you initializing the
>     Transforms for the sub-images ?
>     Are you using the results from the
>     high level registration ?

I use a TranslationTransform which is initialized to (0, 0) for every single
sub-image pair.

> 2) Are you reusing the same instantiation
>     of the optimizer object when you move
>     to the smaller images ?
>     or are you constructing and initializing
>     a new one ?

I'm constructing and initializing a new one every time.
 
> 3) Are you changing the Scaling factors
>     of the optimizer as you move into the
>     smaller images ?

By scaling factors you mean the growth and shrink factors, right? In this case
no, I don't change them. I have tried, but have not been able to come up with
values that work. Also, when I changed them (by decreasing them), my maximum
number of iterations changed (decreased) automatically, despite the fact that it
was explicitly set to a larger value.

I have modified my code to display the intermideate parameters and will need to
run a few examples to see what is going on. I will post my results soon. BTW,
what do you mean by the value returned by the transform?

thanks,

Dennis

> Could you please do the following:
> 
>    Insert a std::cout at the end of the GetValue()
>    method in the metric and print out both the
>    array of current parameters and the value
>    returned by the transform.
> 
>    With the 1+1 optimizer, the Command/Observers will
>    not show you the actual attempts for exploring the
>    region. The will only report the best result found
>    so far.
> 
>    Adding the cout statement in the metric will help
>    you see how far the optimizer is going and whether
>    this is happening in the rotation parameters of the
>    transform or in the translation ones.
> 
> 
> 
> 
> Please let us know what you find.
> 
> 
>    Thanks
> 
> 
> 
>       Luis