[Insight-users] itk::FEM Framework - Adaptive Meshes

[Vincent Magnotta]

Suresh,

First, I am assuming that you are trying to perform a 2D registration based
on the types of elements that you reference. I believe that the only example
for the ITK::fem registration is in DeformableRegistration1.cxx (2D) and
DeformableRegistration11.cxx (3D). The easiest way to work with the fem
registration framework is to have the algorithm create the mesh for you. The
framework supports a hierarchical framework, but the only contain one
material property. You will need to create your own mesh to support multiple
material properties and meshes that conform to anatomical boundaries.

If you can create a mesh and save it in VTK format, then I have previously
posted information on the insight-users list showing how to load the mesh
and convert it into a fem::mesh. In 3D I would suggest IA-FEMesh (
http://www.ccad.uiowa.edu/mimx/IA-FEMesh/). In 2D, I don't have a
recommendation. The ITK::fem framework is something that needs to be updated
and hopefully this will be done with the ITK4.0 initiative. This would
greatly simplify the incorporation of user defined meshes for registration.

I don't know if anyone has done an extensive parameter exploration for the
fem registration. This would be a great addition to the field and would make
an outstanding Insight Journal article.

Vince

On 4/18/10 6:01 PM, "Suresh Joshi" <Suresh.Joshi at insa-lyon.fr> wrote:

> Hello all,
> 
> I'm currently performing registration tests on brain MRI using the ITK
> deformable registration methods. All is going well, except in
> FEM-land.
> 
> Mostly, I know the default mesh created is a rectangular quadrilateral
> mesh, but after reading an ITK registration tutorial, I saw
> comparisons between sparse/dense triangular meshes, adaptive
> quadrilateral meshes and multi-material meshes... Could someone please
> tell me how these adaptive meshes were obtained/created?
> 
> Or perhaps, "Anatomy-specific meshes can be created using public
> domain mesh generators" --> Are there any examples or links to said
> mesh generators? And if there are also any details on how these meshes
> are actually converted into the FEM mesh, could someone please let me
> know?
> 
> The final question is about the parameters. While there seem to be a
> lot of parameters to tune, the suggestions only discuss keeping the
> ratio between rho/E close to 1 and to modify the timestep. And the
> rest of the parameters? They can be left at default?
> 
> The reason I wonder is because I'm trying to do an as-close-to-optimal
> transform parameter comparison, and thus, my laziness (in parameter
> tuning) shouldn't keep FEM from getting good results  :)
> 
> Thanks a lot,
> -Suresh
> _____________________________________
> Powered by www.kitware.com
> 
> Visit other Kitware open-source projects at
> http://www.kitware.com/opensource/opensource.html
> 
> Kitware offers ITK Training Courses, for more information visit:
> http://www.kitware.com/products/protraining.html
> 
> Please keep messages on-topic and check the ITK FAQ at:
> http://www.itk.org/Wiki/ITK_FAQ
> 
> Follow this link to subscribe/unsubscribe:
> http://www.itk.org/mailman/listinfo/insight-users

----------------------
Associate Professor
Department of Radiology
0453-D JCP
200 Hawkins Drive
Iowa City, IA 52242
E-mail: vincent-magnotta at uiowa.edu
Phone: 319-356-8255 Fax: 319-353-6275
Website: http://www.radiology.uiowa.edu