[Insight-users] Interpretation of output results from CenteredRigid2DTransform

[Luis Ibanez]

Hi Michael,

The values that are printed by the CommandIterationUpdate
are not relative to the initial Transform values. They are indeed
the current transform values.

The common mistakes in registration are:

   1)  Failing to initialize the Transform properly
        (Are you using the transform initializer ?)

   2)  Failing to set the parameter scales properly.
        (are you scaling rotations with respect to translations?)

   3)  Using unbalanced values in the settings of the optimizer
        E.g. a step length that is too large..


If you want more details...
then we were need more details about your registration setup   :-)


 Regards,


       Luis


----------------------------------------------------------------------
On Tue, Jul 28, 2009 at 12:22 PM, Michael Jackson <
mike.jackson at bluequartz.net> wrote:

> I am running some code and I am not sure I am interpreting the results
> correctly:
>
>  I have a CenteredRigid2DTransform that I use to register a pair of images.
> During setup I have access to values for the rotation that put me "in the
> ballpark" and so I use that to set the initial transform parameters. (lets
> say for argument sake that the value for the rotation is 0.6 radians).
>
>  As the registration proceeds I use a CommandIterationUpdate object
> (straight out of the Itk guide) to monitor the registration. What concerns
> me is that the rotation shown during the output of the registration is a
> value like 2.21E-5.
>
>  Question 1: Is the value that I see during the registration (as printed to
> the screen through the CommandIterationUpdate object) _relative_ to the
> initial rotation?
>
>  If Question 1 answer is, "No it is absolute" then what might I be doing
> wrong?
>
> If code is needed to elaborate on my question I can try and strip things
> down to try and show what I am doing.
>
> Thanks for any help.
> _________________________________________________________
> Mike Jackson                  mike.jackson at bluequartz.net
> BlueQuartz Software                    www.bluequartz.net
> Principal Software Engineer                  Dayton, Ohio
>
>
>
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