[Insight-users] SignedDanielssonDistanceMapImageFilter

[chensiqi]

I want the distance to the boundary.  The points are located on the boundary and dense enough. I mean that when I connect those points with simple splines it will return well defined closed contour.  I got those data from dcm files, the hospital physicians manually put those point to outline some organs, such as prostate. I want to build an implicit shape model. So the first problem is to convert these point based shape or "explicit" into a signed distance function or "implicit" What about the second question I have there about smart pointer.Is it OK to return a smart pointer from a function?E.g. I have this code:////////////////////////////////////////////////////////////////////// main.cpptypedef itk::Image< unsigned char, 2 > BinaryImageType;typedef itk::Image< float , 2> LSVImageType;LSVImageFilter::Pointer LSVImage = SDF(contour) // where the contour is binary image SDF.cppLSVImageType::Pointer SDF(BinaryImageType::Pointer contour){typedef itk::SignedDanielssonDistanceMapImageFilter <  BinaryImageFilter, LSVImageFilter > FilterType;FilterType::Pointer filter = FilterType::New(); filter ->SetInput ( contour ); // contour is the binary image return filter->GetOutput();} //////////////////////////////////////////////////////////////////// ThanksSiqi> Date: Wed, 10 Dec 2008 15:49:39 -0500> From: luis.ibanez at kitware.com> To: pidanchen at hotmail.com> CC: insight-users at itk.org> Subject: Re: [Insight-users] SignedDanielssonDistanceMapImageFilter> > > Hi chensiqi> > > Here is the philosophical question that you must> answer before your proceed further.> > > You want to get the distance to "what" ?> > > Do you want the distance to the points ?> Do you want the distance to the boundary ?> > > From a set of points located in a boundary is> *very difficult* to find the inside of an object.> > Do you have a topology connecting these points ?> e.g. a triangulated surface ?> > How did you get these points ?> It may be easier to work with the data preceeding> your point extraction.> > > > Regards,> > > > Luis> > > > ==================> chensiqi wrote:> > > > Hi, Luis.> > > > Thanks for the clarification.> > My purpose is to build a signed distance function given a point clouds > > of a shape boundary. I know there are several options to do this. If the > > only input are those points, which is the best, fast and easiest way to > > do this? I know there are several options in ITK.> > 1. FastMarching. > > 2. Reinitiaze> > 3. DistanceMap (Danielsson).> > > > Another question would be regarding smart pointer and raw pointer. Is > > it OK to return a smart pointer from a function?> > E.g. I have this code:> > //////////////////////////////////////////////////////////////////////> > main.cpp> > typedef itk::Image< unsigned char, 2 > BinaryImageType;> > typedef itk::Image< float , 2> LSVImageType;> > LSVImageFilter::Pointer LSVImage = SDF(contour) // where the contour is > > binary image > > SDF.cpp> > LSVImageType::Pointer SDF(BinaryImageType::Pointer contour)> > {> > typedef itk::SignedDanielssonDistanceMapImageFilter < > > BinaryImageFilter, LSVImageFilter > FilterType;> > FilterType::Pointer filter = FilterType::New(); > > filter ->SetInput ( contour ); // contour is the binary image > > return filter->GetOutput();> > } > > > > > > //////////////////////////////////////////////////////////////////////> > > > > > Thanks for any input> > Siqi> > > > > > > Date: Wed, 10 Dec 2008 15:16:08 -0500> > > From: luis.ibanez at kitware.com> > > To: pidanchen at hotmail.com> > > CC: insight-users at itk.org> > > Subject: Re: [Insight-users] SignedDanielssonDistanceMapImageFilter> > >> > >> > > Hi Chensiqi,> > >> > > You are misinterpreting the behavior of this filter.> > >> > > If you have a binary image, where> > >> > > * The foreground object is set to 1 and> > > * The background object is set to 0> > >> > >> > > Then the SignedDanielssonDistanceMapImageFilter will compute> > > the distances to the *transition* region between the 0s and> > > the 1s.> > >> > > All pixesl in the 0s region will have positive distances to> > > that boundary, while all pixels in the 1s region will have> > > negative distances to that boundary.> > >> > > In your case you are feeding an input image where the *boundary*> > > points are set to 1. Therefore, there is no "inside" to the> > > object.> > >> > > E.g. if you are feeding into this distance filter an image with> > > a thin ring, you are not going to find the "inside" of the ring.> > >> > > You should feed this filter with an image containing a filled> > > circle of radius R. Where all the points at locations r < R will> > > be set to 1s. Only in that case will the distance map be able to> > > find the "inside" of the object.> > >> > >> > > Regards,> > >> > >> > > Luis> > >> > >> > > ---------------> > > chensiqi wrote:> > > > Hi, Ghassan> > > >> > > > Thanks for the advice. I flip the input.> > > > The result now is both inside and outside are positive :(> > > >> > > > I use float type as the filteroutput instead of "unsigned short" in > > the> > > > example. I also tried unsigned short, the result is the same.> > > >> > > > Here is part of my code.> > > > > > ////////////////////////////////////////////////////////////////////////////////////////////////////> > > > typedef itk::Image< unsigned char, 2 > BinaryImageType;> > > > typedef itk::Image< float , 2> LSVImageType;> > > > typedef itk::SignedDanielssonDistanceMapImageFilter < > > BinaryImageFilter,> > > > LSVImageFilter > FilterType;> > > > FilterType::Pointer filter = FilterType::New();> > > >> > > > filter ->SetInput ( contour ); // contour is the binary image with> > > > BinaryImageType, 1 at boundary points, and 0 elsewhere.> > > >> > > > LSVImageFilter::Pointer LSVImage = filter->GetDistanceMap();> > > >> > > > Display (LSVImage) // this is a function that displays the image.> > > > > > //////////////////////////////////////////////////////////////////////////////////////////////////////> > > >> > > > I notice when I cout<<LSV_image->GetBufferedRegion().GetSize() , the> > > > output is [0,0]. I guess there is something wrong in my code that> > > > causes this weird output size. I can display LSVImage, although both> > > > inside and outside region are postive.> > > >> > > >> > > > Thanks for any input> > > > Siqi> > > >> > > > > CC: insight-users at itk.org> > > > > From: hamarneh at gmail.com> > > > > To: pidanchen at hotmail.com> > > > > Subject: Re: [Insight-users] SignedDanielssonDistanceMapImageFilter> > > > > Date: Tue, 9 Dec 2008 20:45:19 -0800> > > > >> > > > > Hello Siqi,> > > > >> > > > > You write: "The input is only a binary image with boundary points at> > > > > 0, and all other points at 1."> > > > > However, according to he documentation: "As a convention, the > > distance> > > > > is evaluated from the boundary of the ON pixels."> > > > > (from> > > > > > http://www.itk.org/Doxygen/html/classitk_1_1SignedDanielssonDistanceMapImageFilter.html > > > > > >> > > > > )> > > > > So, your input image should have boundary pixels set to 1 and all> > > > > other points to 0 (and not the other way around).> > > > > HTH,> > > > > /Ghassan> > > > >> > > > >> > > > >> > > > > On 9-Dec-08, at 7:24 PM, chensiqi wrote:> > > > >> > > > > >> > > > > > Hi, ITKers> > > > > >> > > > > > I got two ques tions regarding > > SignedDanielssonDistanceMapImageFilter.> > > > > >> > > > > > 1. The result I have is not "signed", both the inside and outside> > > > > > distance values are negative. The input is only a binary image with> > > > > > boundary points at 0, and all other points at 1. I was wondering> > > > > > how I was wondering how SignedDanielssonDistanceMapImageFilter> > > > > > determine the region of inside and outside.> > > > > >> > > > > > 2. In Examples of SignedDanielssonDistanceMapImageFilter. cxx, I> > > > > > notice that the OutputImageType of filter is unsigned short, > > which I> > > > > > don't quite understand. The output should contains both negative> > > > > > and positive distance, why use "unsigned" here?> > > > > >> > > > > > Thanks> > > > > > Siqi> > > > > >> > > > > > MSN保护盾，十八般武艺保障MSN安全！ 现> > > > > > 在就下载！ _______________________________________________> > > > > > Insight-users mailing list> > > > > > Insight-users at itk.org> > > > > > http://www.itk.org/mailman/listinfo/insight-users> > > > >> > > >> > > >> > > > > > ------------------------------------------------------------------------> > > > MSN热搜榜全新升级，更多排行榜等着你！ 立即查看！ < > > http://top.msn.com.cn>> > > >> > > >> > > > > > ------------------------------------------------------------------------> > > >> > > > _______________________________________________> > > > Insight-users mailing list> > > > Insight-users at itk.org> > > > http://www.itk.org/mailman/listinfo/insight-users> > > > > > ------------------------------------------------------------------------> > 使用新一代 Windows Live Messenger 轻松交流和共享！ 立刻下载！ > > <http://im.live.cn/>
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