[Insight-users] Fast marching to calculate distance map

[siqi chen]

Hi, Kevin,

Thanks for your reply. However, I still can't get it to work. Here is my
simple code, where I want to calculate the distance map to point [50,50]. I
write the output of the FastMarching filter to .vtk file and open it in
Paraview.

    typedef itk::Image<float,2> ImageType;
    typedef itk::FastMarchingImageFilter<ImageType,ImageType
>FastMarchingFilterType;
    FastMarchingFilterType::Pointer fastMarching =
FastMarchingFilterType::New();
    typedef FastMarchingFilterType::NodeContainer        NodeContainer;
    typedef FastMarchingFilterType::NodeType             NodeType;
    /////// alive points
    NodeContainer::Pointer alivePoints = NodeContainer::New();
    alivePoints->Initialize();
    NodeType nodeAlive;
    ImageType::IndexType index; index[0]=50; index[1]=50;
    nodeAlive.SetValue(0.0);
    nodeAlive.SetIndex(index);
    alivePoints->InsertElement(0,nodeAlive);
    fastMarching->SetTrialPoints(alivePoints);

     ImageType::IndexType start; start[0]=0; start[1]=0;
     ImageType::SizeType size; size[0]=100; size[1]=100;
     ImageType::RegionType region; region.SetSize(size);
region.SetIndex(start);
     fastMarching->SetOutputRegion(region);
    fastMarching->SetSpeedConstant(1.0);
    fastMarching->SetStoppingValue(10);
    typedef itk::ImageFileWriter<ImageType> WriterType;
    WriterType::Pointer writer = WriterType::New();
    writer->SetFileName("fastMarching.vtk");
    writer->SetInput(fastMarching->GetOutput());
    writer->Update();

Thank you for any input.
Siqi


On Tue, Dec 29, 2009 at 4:25 PM, Kevin H. Hobbs <hobbsk at ohiou.edu> wrote:

> On 12/29/2009 03:10 PM, siqi chen wrote:
> > Hi, ITKers,
> >
> > I have a simple question regarding how to use FastMarchingImageFilter to
> > calculate distance map.
> >
> > If I have a pointset P with integer coordinates, and I want to calculate
> a
> > distance map to P. What should I pass to FastMarchingImageFilter?
> >
> > What I did is:
> > 1. pass P to AlivePoints with value 0.0,
> > 2. pass all the 4 neighbors of P to TrialPoints with value 1.0
> > 3. set the speedconstant to 1.0
> > 4. set the outputregion, size, origin, ....
> >
> > Am I missing something?
> >
>
> 1. pass P to TrialPoints with value 0.0
> 2. set the speedconstant to 1.0
> 3. set the outputregion, size, origin, ....
>
>
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