[Insight-users] about fast marching level set

[Yixun Liu]

Hi,

I use the example located in ITK-2.6\Examples\Segmentation\ShapeDetectionLevelSetFilter.cxx. When I run this example I want to visualize the result of fast marching after each iteration. So I add a observer to observe the iterationEvent of fast marching filter. I set the speed of fast marching to 1.0 and the initial distance to -20. My image is 256x256x48 and spacing is 1x1x3. I have three problems.

1. I add the observer: fastMarching->AddObserver(itk::IterationEvent(), this->fastMarchingObserver), but the fastMarching does not invoke the itk::IterationEvent. I add observer to shapeDetectionLevelsetFilter and it does invoke this event. Why does fast marching not invoke this event?

2. Because I cannot observer the IterationEvent of the fast marching, I add a observer to observe the EndEvent of fastmarching. After the fast marching end I visualize the result of fast marching in traversal, sagital and coronal slices. The result in traversal is a round, but the results in sagital and coronal are ellipse. I guess the results should be round in three slices. Is it caused by  different spacing?

3. I vusualize the result of each iteration and stop it when the front come to the boundary. However ,I do not know how to stop it. I intend to add a observer to observe the IterationEvent of ShapeDetectionLevelSetFiler.After each iteration the observer determine if stop the iteration. Which method should I call to stop the iteration?

Any suggestion would be greatedly appreciated!

Regards,

Yixun Liu
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