[Insight-users] Geodesic Active Contour - Deflate

[ALBERT Aurélien]

Hi,

I made my first code using ITK, and I'm facing a problem :

I try to detect objects in an image using the GeodesicActiveContourLevelSet image filter.

So my filters are :


Import => Smoothing => Gradient magnitude => Sigmoid \
                                                                                              |==> Geodesic Active Contour => Tresholder
                                                                      Fast Marching /

In attachment, here is my sigmoid output image. I think the sigmoid is very well computed (I try to extract an helicopter from the image).

My problem is about the Geodesic Active Contours parameters : by default it works by "inflation" : in my case this is a problem because the shape contains some "holes" so I thought about 2 solutions :

1. "fill the holes" in the sigmoid output => is it a good idea ? How to do that ?
2. set the  Geodesic Active Contours parameters to "deflation" => How to do that ? I tried using a negative propagation speed, but there is no changes...

Here are my parameters :


	p_sigmoidFilter->SetOutputMinimum(0.0);
	p_sigmoidFilter->SetOutputMaximum(1.0);
	p_sigmoidFilter->SetAlpha(-0.5);
	p_sigmoidFilter->SetBeta(3.0);

	p_gradientMagnitudeFilter->SetSigma(sigma);

	p_fastMarchingFilter->SetTrialPoints(p_fastMarchingSeeds);
	p_fastMarchingFilter->SetSpeedConstant(1.0);

	p_geodesicActiveContourFilter->SetPropagationScaling(2.0);
	p_geodesicActiveContourFilter->SetCurvatureScaling(1.0);
	p_geodesicActiveContourFilter->SetAdvectionScaling(1.0);
	p_geodesicActiveContourFilter->SetMaximumRMSError(0.02);
	p_geodesicActiveContourFilter->SetNumberOfIterations(800);


Thansk a lot for any help !
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