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<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><SPAN style="FONT-SIZE: 10pt; COLOR: black; FONT-FAMILY: Arial">Hi Luis, <?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" /><o:p></o:p></SPAN></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><SPAN style="FONT-SIZE: 10pt; COLOR: black; FONT-FAMILY: Arial">Thank you for your suggestions. I will give a try and hope and get some good results.<o:p></o:p></SPAN></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><SPAN style="FONT-SIZE: 10pt; COLOR: black; FONT-FAMILY: Arial">Thank you<o:p></o:p></SPAN></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><SPAN style="FONT-SIZE: 10pt; COLOR: black; FONT-FAMILY: Arial">Best regards <o:p></o:p></SPAN></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><SPAN style="FONT-SIZE: 10pt; COLOR: black; FONT-FAMILY: Arial">Juliette<o:p></o:p></SPAN></P>
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<B><SPAN style="FONT-WEIGHT: bold">De :</SPAN></B> Luis Ibanez <luis.ibanez@kitware.com><BR><B><SPAN style="FONT-WEIGHT: bold">À :</SPAN></B> Juliette Deniau <juliette.deniau@yahoo.fr><BR><B><SPAN style="FONT-WEIGHT: bold">Cc :</SPAN></B> insight-users@itk.org<BR><B><SPAN style="FONT-WEIGHT: bold">Envoyé le :</SPAN></B> Mercredi, 10 Décembre 2008, 19h25mn 59s<BR><B><SPAN style="FONT-WEIGHT: bold">Objet :</SPAN></B> Re: Re : Re : [Insight-users] active contour, snake, deformable model and level set segmentation ???<BR></FONT><BR><BR><BR>Hi Juliette,<BR><BR>Thanks for the additional information about the problem that you are<BR>trying to solve.<BR><BR>LevelSet filters may not be the ideal tool for segmenting objects with<BR>high curvatures. At least not the GeodesicActiveContour nor the Shape<BR>Detection level set implementations.<BR><BR>You may want to give it a try at:<BR><BR><BR> a) ThresholdSegmentationLevelSet<BR> b)
FastMarchingLevelSet<BR><BR><BR>(a) Will depend strongly on the intensity levels of the input image,<BR> and therefore will behave close to the Region Growing filters,<BR> (ConfidenceConnected and ConnectedThreshold).<BR><BR><BR>(b) Will depend strongly on the gradient magnitude of the input image.<BR> That is, if your input image have well-defined edges around the<BR> objects of interests (the weapons) then the segmentation will be<BR> well contained.<BR><BR> Otherwise, the segmentation will tend to "leak" in regions where<BR> the edge has low contrast.<BR><BR><BR>If you are doing this from CT images, you probably should try to take<BR>advantage of the fact that the Hounsfiel Units are somehow normalized.<BR>However, presumably, the objects of interest will be surrounded by objects of great diversity, and it may not be possible to count on<BR>having a good
contrast against the background.<BR><BR><BR>I'll suggest you to give it a try to the two filters above, but be<BR>aware that you still will have to fine tune a set of parameters...<BR><BR><BR><BR> Regards,<BR><BR><BR><BR> Luis<BR><BR><BR><BR><BR>----------------------<BR>Juliette Deniau wrote:<BR>> Thank you Luis for your massage and patience!<BR>> <BR>> Sorry for my question, I'm just a student not an expert! But according to my reading in active contour and level set papers, I have found most of papers that are combining somehow level set with active contour which means that are not the same!<BR>> <BR>> Any way what I would like to segment as object are weapon objects (knifes and guns from data base of still images(2D)).<BR>> <BR>> These objects are usually small and thin in particular for the knife objects. I have already tested the region growing (Confidence connected filter), it
gives acceptable results but it depends highly in the parameters, in particular the factor parameter.<BR>> <BR>> Now I try to use level set and active contour based segmentation since they are more robust than the region growing methods.<BR>> <BR>> Hope I have well explained my problem and hope I can get help and guidance from you. <BR>> Many thanks.<BR>> <BR>> Regards <BR>> Juliette<BR>> <BR>> <BR>> <BR>> ------------------------------------------------------------------------<BR>> *De :* Luis Ibanez <<A href="mailto:luis.ibanez@kitware.com" ymailto="mailto:luis.ibanez@kitware.com">luis.ibanez@kitware.com</A>><BR>> *À :* Juliette Deniau <<A href="mailto:juliette.deniau@yahoo.fr" ymailto="mailto:juliette.deniau@yahoo.fr">juliette.deniau@yahoo.fr</A>><BR>> *Cc :* <A href="mailto:insight-users@itk.org" ymailto="mailto:insight-users@itk.org">insight-users@itk.org</A><BR>> *Envoyé le :* Jeudi, 4
Décembre 2008, 19h46mn 27s<BR>> *Objet :* Re: Re : [Insight-users] active contour, snake, deformable model and level set segmentation ???<BR>> <BR>> <BR>> Hi Juliette,<BR>> <BR>> <BR>> I'm not sure what you mean by:<BR>> <BR>> <BR>> "Level set (purely level set without active contour)<BR>> based segmentation?"<BR>> <BR>> <BR>> The level set abstraction is implemented in such a way that at<BR>> every pixel ITK solves an increment of a partial differential<BR>> equation.<BR>> <BR>> <BR>> The surface of the object happens to be defined at the loci<BR>> where the level set image has zero values..<BR>> <BR>> <BR>> <BR>> <BR>> In practice, the distinction between a LevelSet and an Active<BR>> Contours (or Snakes) is mostly of importance for those researchers<BR>> who need to complete their annual quota of published papers and<BR>> therefore are forced to be
inventing "new" things every time, even<BR>> when they are reincarnations of older ideas.<BR>> <BR>> <BR>> In essence, the difference between LevelSets and Active contours<BR>> is one of software implementation.<BR>> <BR>> <BR>> If you need to solve a real and practical problem, we could<BR>> advice you on what ITK methods to use.<BR>> <BR>> <BR>> If you are in need of a flashy name for a segmentation method<BR>> then... there is a lot out there to choose from. :-)<BR>> <BR>> <BR>> Regards,<BR>> <BR>> <BR>> Luis<BR>> <BR>> <BR>> ----------------------<BR>> Juliette Deniau wrote:<BR>> > Hi Luis,<BR>> ><BR>> > A one more question to clear completely my understanding.<BR>> ><BR>> > You said that “The Level Set implementations of deformable models have all<BR>> > the "LevelSet"
string as part of their name” . Does this means that there is no<BR>> ><BR>> > level set (purely level set without active contour) based segmentation?<BR>> > Thank you for your time<BR>> ><BR>> > Juliette<BR>> > ><BR>> > ------------------------------------------------------------------------<BR>> > *De :* Luis Ibanez <<A href="mailto:luis.ibanez@kitware.com" ymailto="mailto:luis.ibanez@kitware.com">luis.ibanez@kitware.com</A> <mailto:<A href="mailto:luis.ibanez@kitware..com" ymailto="mailto:luis.ibanez@kitware.com">luis.ibanez@kitware.com</A>>><BR>> > *À :* Juliette Deniau <<A href="mailto:juliette.deniau@yahoo.fr" ymailto="mailto:juliette.deniau@yahoo.fr">juliette.deniau@yahoo.fr</A> <mailto:<A href="mailto:juliette.deniau@yahoo.fr"
ymailto="mailto:juliette.deniau@yahoo.fr">juliette.deniau@yahoo.fr</A>>><BR>> > *Cc :* <A href="mailto:insight-users@itk.org" ymailto="mailto:insight-users@itk.org">insight-users@itk.org</A> <mailto:<A href="mailto:insight-users@itk.org" ymailto="mailto:insight-users@itk.org">insight-users@itk.org</A>><BR>> > *Envoyé le :* Mardi, 2 Décembre 2008, 21h04mn 06s<BR>> > *Objet :* Re: [Insight-users] active contour, snake, deformable model and level set segmentation ???<BR>> ><BR>> ><BR>> > Hi Juliette,<BR>> ><BR>> ><BR>> > Your observations are correct.<BR>> ><BR>> > If you are looking for a mesh-based implementation of a deformable model, then you should look at<BR>> > <A href="http://www.itk.org/Insight/Doxygen/html/classitk_1_1DeformableSimplexMesh3DBalloonForceFilter.html"
target=_blank>http://www.itk.org/Insight/Doxygen/html/classitk_1_1DeformableSimplexMesh3DBalloonForceFilter.html</A><BR>> ><BR>> ><BR>> > and its example application in<BR>> ><BR>> > InsightApplications/DeformableModelSimplexMesh<BR>> ><BR>> ><BR>> > This is closer to what is known as "Snakes" in the medical field.<BR>> ><BR>> > The Level Set implementations of deformable models have all<BR>> > the "LevelSet" string as part of their name.<BR>> ><BR>> ><BR>> > They will be:<BR>> ><BR>> ><BR>> > $ find . -name "*LevelSetImageFilter.h"<BR>> > ./itkAnisotropicFourthOrderLevelSetImageFilter...h<BR>> > ./itkCannySegmentationLevelSetImageFilter.h<BR>> > ./itkCurvesLevelSetImageFilter.h<BR>> >
./itkGeodesicActiveContourLevelSetImageFilter.h<BR>> > ./itkGeodesicActiveContourShapePriorLevelSetImageFilter.h<BR>> > ./itkIsotropicFourthOrderLevelSetImageFilter.h<BR>> > ./itkLaplacianSegmentationLevelSetImageFilter.h<BR>> > ./itkNarrowBandCurvesLevelSetImageFilter.h<BR>> > ./itkNarrowBandLevelSetImageFilter.h<BR>> > ./itkNarrowBandThresholdSegmentationLevelSetImageFilter.h<BR>> > ./itkSegmentationLevelSetImageFilter.h<BR>> > ./itkShapeDetectionLevelSetImageFilter.h<BR>> > ./itkShapePriorSegmentationLevelSetImageFilter.h<BR>> > ./itkThresholdSegmentationLevelSetImageFilter.h<BR>> > ./itkUnsharpMaskLevelSetImageFilter.h<BR>> > ./itkVectorThresholdSegmentationLevelSetImageFilter.h<BR>> ><BR>> ><BR>> ><BR>> > Please let us know if you have further
questions,<BR>> ><BR>> ><BR>> > Thanks<BR>> ><BR>> ><BR>> > Luis<BR>> ><BR>> ><BR>> ><BR>> > ------------------------<BR>> > Juliette Deniau wrote:<BR>> > > Hi All,<BR>> > ><BR>> > > I’m confused about what type of segmentation methods are within itk, in particular the ones related to active contour and level set?<BR>> > ><BR>> > > In my understanding, active contour is the same as a deformable model and the same as a snake. The levelset segmentation is another type (use a PDE to evolve the curve).<BR>> > ><BR>> > > In itk there are some active contours implemented with the level set framework like the CurvesLevelSetImageFilter, I’m
alright?<BR>> > ><BR>> > > Can any one tell me what are the segmentation filters which are purely active contour (snake) and those which use level set to evolve the curve? > Sorry if my question is too stupid!<BR>> > ><BR>> > > Thanks a lot<BR>> > ><BR>> > > Juliette<BR>> > ><BR>> > ><BR>> > ><BR>> > > ------------------------------------------------------------------------<BR>> > ><BR>> > > _______________________________________________<BR>> > > Insight-users mailing list<BR>> > > <A href="mailto:Insight-users@itk.org" ymailto="mailto:Insight-users@itk.org">Insight-users@itk.org</A> <mailto:<A href="mailto:Insight-users@itk.org"
ymailto="mailto:Insight-users@itk.org">Insight-users@itk.org</A>> <mailto:<A href="mailto:Insight-users@itk.org" ymailto="mailto:Insight-users@itk.org">Insight-users@itk.org</A> <mailto:<A href="mailto:Insight-users@itk.org" ymailto="mailto:Insight-users@itk.org">Insight-users@itk.org</A>>><BR>> > > <A href="http://www..itk...org/mailman/listinfo/insight-users" target=_blank>http://www..itk..org/mailman/listinfo/insight-users</A> <<A href="http://www.itk..org/mailman/listinfo/insight-users" target=_blank>http://www.itk..org/mailman/listinfo/insight-users</A>> <<A href="http://www.itk.org/mailman/listinfo/insight-users" target=_blank>http://www.itk.org/mailman/listinfo/insight-users</A>><BR>> ><BR>> <BR></DIV></DIV></div><br>
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