[Insight-users] Advection

[Iván Macía]

Hi Maria,

In the general context of partial differential equations, advection refers
to the transport of an scalar quantity in a vector field. 

http://en.wikipedia.org/wiki/Advection_equation

In our case, advection refers to the movement of the level-set by means of a
velocity field. 

If not set explicitly to one of the ITK level-set filters, this is usually
calculated as the gradient vector of the feature image provided by the user
to the filter. As the feature image is an edge map, calculating the gradient
of this edge map results in a vector field that points towards the edges
and, when close enough to the edges, attracts the curve to them.

You can find fore information in the ITK software guide or in the text of
Sethian "Level-Set Methods and Fast Marching Methods".

Hope that helps

Iván



-----Mensaje original-----
De: insight-users-bounces+imacia=vicomtech.es at itk.org
[mailto:insight-users-bounces+imacia=vicomtech.es at itk.org] En nombre de
Maria Cira Avvinto
Enviado el: domingo, 03 de diciembre de 2006 16:09
Para: insight-users
Asunto: [Insight-users] Advection

Hi,
I am looking for input on following questions:
What is the significance of Advection term in Equation for Level Set
Segmentation?
Thanks a lot,
Mary
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