[Insight-users] ImageToParametricSpaceFilter Problem

[Ashley G. Anderson III]

Hello everyone,
I am very new to ITK and I am trying to learn it for a class project. 
Most of it seems to make a lot of sense so for, but I am stuck at one 
point. I am playing around trying to implement a simple vessel-detection 
program similar to the Curves2DExtraction application, but I am having 
trouble with the ImageToParametricSpaceFilter. It seems to not produce 
any output. Here is the code I am using, which is basically taken 
straight from the Curves2DExtraction application:

    ParametricSpaceFilterType::Pointer m_ParametricSpace = 
ParametricSpaceFilterType::New();

    m_ParametricSpace->SetInput( 0, 
m_RescaleIntensitySmoothed->GetOutput() );
    m_ParametricSpace->SetInput( 1, 
m_RescaleIntensityMedialness->GetOutput() );
    m_ParametricSpace->SetInput( 2, 
m_RescaleIntensityMaxEigen->GetOutput() );
    m_ParametricSpace->Update();

    std::cout << m_ParametricSpace->GetOutput()->GetNumberOfPoints();

The cout statement at the end tells me there are zero points in the 
output. Is there something obvious I am doing wrong? I have checked the 
output of all three RescaleIntensityFilter images, and they look fine.

Thanks in advance,
Ashley