[Insight-users] Optical flow visualization

[Luis Ibanez]

Hi Jayant,

There are two things that you could interpret as being
the "optical flow" in the GeodesicActive contours.

A) The advection image

B) The displacements of the zero set
    from one iteration to another.

If what you have in mind is (A), then you can
visualiza it by calling


     GACFilter->GetAdvectionImage()

this will return a vector image that you can save
in order to visualize with ParaView, or that you
can pass to VTK and apply glyhphs on it.


If what you have in mind is (B), then it is more
tricky because the only thing you will have is the
position of the zero set at one iteration and the
position of the level set at the previous iteration.

Since the zero set doesn't move more that one pixel
at each iteration, you could visit all the pixels
from the zero set of one iteration and read the
values of the Level set from the past iteration
(that means that you have to save the level set
of the previous iteration in an auxiliary image).

Those values will tell you how far the current
contour is now from its previous position.
and therefore it is a measure of the optical
flow of the level set at that iteration.


Please let us know if that's what you had
in mind.


    Thanks


      Luis


--------------------
Jayant Chauhan wrote:

> Hey Luis,
>  
> How can I visualize the optical flow (I am using 
> GeodesicActiveContourLevelSetImagefilter)? Is the optical flow the same 
> as the Speed image ?! Do I hve to use the function GetSpeedImage or 
> something lke taht ?! A pointer would help.
>  
> with regards
> Jayant
>