[Insight-users] Re: VersorRigid3DTransform

[Luis Ibanez]

Hi Radhika,


A) This message means that you transform is so far
    off that the images are not overlapping anymore.

    This usually happens when you use an optimization
    step that is too large and make the transform diverge.


B) If the images are of the same modality and about the
    same histogram you should be ok using the MeanSquares
    ImageMetric. However... the metric value shouldn't
    be that high. It is



C) You can verify the origin and spacing by printing out

    std::cout << fixedImage->GetSpacing() << std::endl;
    std::cout << fixedImage->GetOrigin()  << std::endl;

    or by printing all the image information with

    fixedImage->Print( std::cout );


D) ok, The initialization should be fine.


E) In MyPACS you have the option of posting "shared" (public)
    cases as well as "private" cases. The private level is
    supposed to be as secure as any other PACS system.


F) You can try the equivalent registration algorithm
    with the free version of VolView
    http://www.kitware.com/products/volview.html
    Just load one image, then go to the View->Filters
    menu and select

     "Registration" ---> "Image Registration (ITK)"

    then in the button "Second input" browse for the
    second image (the moving image).


G) Please post the tracing messages that are printed out
    when the example runs (the sequence that displays the
    values of the metric and the values of the parameters
    for each iteration).




Regards,


   Luis


----------------------------------
Radhika Sivaramakrishna wrote:

> Hi Luis,
> 
> Basically I used your example in ImageRegistration8.cxx as is, so I did use
> Optimizerscale.
> 
> To answer your questions in order:
> 
> A) I used the metric MeanSquaresImageToImageMetric (as the example does) 
> and after about 89 iterations this is the error I got!
> 
> 
> ExceptionObject caught !
> 
> itk::ExceptionObject (0x82c4738)
> Location: "Unknown"
> File: 
> /home/rsivaram/Insight/Code/Algorithms/itkMeanSquaresImageToImageMetric.txx
> Line: 103
> Description: itk::ERROR: MeanSquaresImageToImageMetric(0x82bc698): All 
> the points mapped to outside of the moving image
> 
> B) These images are brain MRI T1-weighted images.
> 
> C) How do I verify the origin and spacing? Basically I am trying to test 
> this currently on a simulated case where I have created one of the 
> images from the other by a known transformation, so is this still an issue?
> 
> D) Again initialization of the transform is exactly as in 
> ImageRegistration8.cxx.
> 
> My concern about posting the images is privacy issues since these are 
> from a hospital and there may be HIPAA issues. How accessible are
> 
> these images to the outside world?
> 
> Thanks
> Radhika
> 
> 
>