[Insight-users] 3D deformable registration

[Luis Ibanez]

Hi Vijay,

If you are interested in a 3D version of the FEM deformable
registration example, you may want to look at the example:

         Insight/Examples/Registration/
                DeformableRegistration11.cxx

and the associated input file:


          Insight/Examples/Data/
                FiniteElementRegistration3.txt


The example: DeformableRegistration11.cxx is the 3D version
              DeformableRegistration1.cxx



The pixel dimensions (pixel spacing) are taken from the
meta information of the image. There is no need for you
to put it in the parameters file.



The values of Elasticity and RhoC must be found through
experimentation.

As a rule of Thumb, high elasticity implies that a very
strong force applied to the material will produce very
small deformations.  Therefore, you could start running
experiments with large values of elasticity. If you find
that the deformation field has vectors with very small
magnitudes, then you know that the Elasticity can be
reduced. If you find that the deformation vectors are too
large (e.g. the anatomical tissue gets displaced too far)
then you will know that the Elasticity is too low.

Note that you may have to play with the orders of magnitude
of the Elasticity.


The RhoC factor is used for computing the Mass matrix,
and its final effect is to multiply the forces applied
to the model. Therefore, large values of RhoC will result
on larger deformations, while small values of Rhoc will
result in smaller deformations.




    Regards,



       Luis



------------------
vijay kumar wrote:
> Hi,
> I would like to register two 3D images that are of different sizes ([nx1 
> ny1 nz1] & [nx1 ny2 nz2] voxels) and different voxel dimensions. I 
> modified DeformableRegistration1.cxx to accept 3D images, but I have 
> questions about the parameters file 
> (FiniteElementRegistrationParameters1.txt):
>  
> 1. How do I specify the sizes of both images? The section - Information 
> about image inputs has the option to specify only one set of sizes. How 
> do I specify the second set?
>  
> 2. How do I include voxel dimensions? Or, will the program get this 
> info from the image header?
>  
> 3. How do we determine appropriate E, RhoC and Alpha values? Are there 
> some guidelines for their choice?
>  
> Thanks,
> Vijay
>  
>  
> 
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