[Insight-users] New user questions about ITK level set and FEM package

[Irina IONESCU]

Hello ITK group,

I'm a new user, and I'd like to use the level sets and FE capabilities 
of ITK.
I have a few questions regarding the following issues:

1.
Ref. Figure 9.14: The implicit level set surface G is the black line 
superimposed over the image grid. The
location of the surface is interpolated by the image pixel values. The 
grid pixels closest to the implicit
surface are shown in gray.

Is the distance value stored at the pixel ('center point' of the pixel 
area) or at the corners of the pixels (not sure what 'grid pixels' 
mean)? How is the interpolation carried on? My confusion arrises from 
Figure 4.1: Geometrical concepts associated with the ITK image, I don' 
know how to interpret it.

2.
FEM Package

Would you please give me some more indepth references about the FEM 
package available in ITK?
The following questions might be silly, but I am confused and I need 
your help in understanding basic concepts.
I've found a ppt file that describes the various types of elements 
available but I would like to know more on how the mesh can be 
constructed, and what is a node in a FE mesh, a pixel or a grid point?  
Which one is used to store the information?
In the Registration chapter in user's manual everythign is in terms of 
points and vectors, for the FE package, are the mesh nodes points?
I'm asking this to understand better how to use the Marching cube in 
conjunction with the FE, and how to think in terms of applying boundary 
conditions for a specific problem.

Thank you very much for your kind help.

Irina


_______________________________________________________________
Irina Ionescu, Ph. D.
Ecole Centrale de Nantes
GéM - Institut de Recherches en Génie Civil et Mécanique  UMR CNRS 6183
Equipe "Structure et Simulation"
B.P. 92101, 44321 Nantes cedex 3, FRANCE
+33 (0) 2 40 37 25 81
irina.ionescu at ec-nantes.fr
_______________________________________________________________