[Insight-users] Registration3D

[Luis Ibanez]

Hi Ravi,

Your code for centering the images looks fine.

You can always double check if the new origin
is correct by printing out the image information
with something like

fixedcenterer->GetIOutput()->Print( std::cout );
movingenterer->GetIOutput()->Print( std::cout );

---

What values are you using for the  translationScaling ?

Keep in mind that the Euler3D transform represents
rotations as three angles in radians, so their dynamic
range is much lower than the translations dynamic range.

A new balance between the learningRate and the
translationScaling may help to make the optimization
more stable.

You may also break the process in two stages:
a first one in which you do only translations at
big steps. (using translation transform), followed
by a second registration in which you use a rigid
transform with small steps, for fine tunning the
translation and correct for rotation.
This approach may make sense if the image miss-registration
is composed by a small rotation and a large translation.


Regards,


    Luis




--------------------
ravi sharma wrote:
> Well I have a strange problem with my 3D multimodality
> registration program.My program is able to correct
> translations but after correcting translations it
> starts to misregister...the rotations just go
> haywire(optimizer goes to a minimum value and
> translations are corrected but at this point the
> rotations start to occur and optimizer wrongly moves
> to maximize cost function).It doesnot correct any
> rotations and even if I take the same image as fixed
> and moving it starts to rotate the moving image.I am
> using Euler3D transform and
> MattesMutualInformation.After running the program with
> various test cases I think it is a problem with the
> way I set the centers of the images perhaps.
>   I read the fixed and moving images then Using
> ChangeInformationImageFilter I do the following
> 
> 
> 
>   FixedCentererType::Pointer fixedcenterer =
> FixedCentererType::New();
>   MovingCentererType::Pointer movingcenterer =
> MovingCentererType::New();
>   fixedcenterer->CenterImageOn();
>   movingcenterer->CenterImageOn();
>  
> fixedcenterer->SetInput(fixedImageReader->GetOutput());
>  
> movingcenterer->SetInput(movingImageReader->GetOutput());
> 
> After this I cast the outputs of thes to float and set
> those images as registration images.After this I use
> simply the Transform and dont do anything with the
> centers.What could be the problem.
> 
> __________________________________
> Do you Yahoo!?
> Yahoo! SiteBuilder - Free, easy-to-use web site design software
> http://sitebuilder . yahoo . com
> _______________________________________________
> Insight-users mailing list
> Insight-users at itk . org
> http://www . itk . org/mailman/listinfo/insight-users
>