dolfin team mailing list archive

[Johan Hake <hake@xxxxxxxxx>]

On Tuesday 24 February 2009 01:08:11 A Navaei wrote:
> Finally after all those long discussions on the best way of
> architecturing variational image processing problems based on dolfin,
> a minimal demo showing how to solve a classical motion estimation PDE
> is available now -- thanks for all the support. Detailed explanation
> is given here:
>
> http://code.google.com/p/debiosee/wiki/DemosOptiocFlowHornSchunck
>
> Currently, the c++ implementation is done and the python wrapper is on the
> way.

Cool!

> I have tried to perform sub-classing as much as possible and leave the
> rest to be implemented outside of the main classes. While this works,
> there is a tiny problem which I'm not quite happy about. Here is
> what's happening:
>
> [ITK-backend]
>
>       v
> [GenericImage]-------\
>
>       v              |
> [ImageToMesh]        |
>
>       v              |
> [FunctionSpace]      |
>
>       v              |
> [ImageFunction]<-----/
>
> If you still cannot see what's happening, get a monospace font :) What
> I don't like is the right branch connecting GenericImage to
> ImageFunction. There should be a way of making sure that the two
> branches are initiated from the same image source, or this could be a
> source of error. Simply encapsulating this in a class takes away the
> freedom of defining a general problem away from the user.

Just a thought:

Would it help to let GenericImage also be a dolfin::Mesh? Then in ITKImage you 
copy paste the algorithm for creating a UnitCube/UnitSquare/Rectange/Box 
(the algorithms are actually not very large). 

This means that you do not have to pass the ImagePointerType to ImageFunction, 
but only the FunctionSpace containing the ITKImage as a mesh?

Johan

> Another problem is converting images back from functions. To do that,
> we need image dimension, size and data pointer. Of these, it seems
> that there is no way to re-construct image size from a given function
> (any Function, not just ImageFunction, eg the solution of a PDE)
> asuming that the corresponding mesh is a structured grid. For
> instance, does UnitSquare store the input parameters from which the
> image size can be restored?
>
>
> -Ali
> _______________________________________________
> DOLFIN-dev mailing list
> DOLFIN-dev@xxxxxxxxxx
> http://www.fenics.org/mailman/listinfo/dolfin-dev