[ITK] Fwd: FEM registration, minimal working example

[Matt McCormick]

Hello Luigi,

> I am trying to set up a minimal working example using
> itkFEMRegistrationFilter.The idea is to simplify DeformableRegistration1.
>
> I am using ITK 4.7.1 under Windows 7 with MinGW32 and I have read the
> following documentation:
>
> ITK Software guide - Design and functionality (page 267);
> ITK ppt on FEM (here);
>
> Anyhow, I still do not quite understand how DeformableRegistration1 works.
>
> citing from the documentation: "To use this filter the user will at a
> minimum set the Fixed and Moving images. If the user does not specify a mesh
> using the SetInputFEMObject() then a mesh will be created automatically of
> the appropriate type (2d=quads and 3d=hex)."  I have tried with no success
> running this code (it compiles but crashes):
>
> registrationFilter->SetFixedImage(fixedImageReader->GetOutput());
> registrationFilter->SetMovingImage(movingImageReader->GetOutput());
> registrationFilter->RunRegistration();

To understand why it is crashing, make sure to catch an print
exceptions with try-catch statements. If that is not informative,
compile with the Debug CMAKE_BUILD_TYPE, and run with GDB.


> why the basic examples has to pass through image reading, image intensity
> re-scaling, image re-reading and image registration? Is this required to run
> FEM registration?

In this case, there is intensity rescaling and histogram equalization,
which helps the matching metric do a better comparison.


> is there a place where I could find more documentation and tutorials on FEM
> registration?

The tests (found in the "tests" directory of the module) can also be
information.

Hope this helps,
Matt