[Insight-users] Radius of Gaussian?

[motes motes]

How should the radius of the gaussian be understood? I have done this:

    const unsigned int gaussianDim = 1;
    typedef itk::GaussianSpatialObject<gaussianDim>        GaussianType;
    typedef itk::Point<double, gaussianDim>                GaussianPoint;

    const static int gaussian_radius = 512;
    const static int gaussian_max = 1;
    GaussianType::Pointer m_Gaussian = GaussianType::New();
    m_Gaussian->SetMaximum(1);
    m_Gaussian->SetRadius(512);

    GaussianPoint pos;
    for (int i=0; i<100; i++) {
      pos[0] = -300 + i*5;

      double weight = 0.0;
      m_Gaussian->ValueAt(pos, weight);
      std::cout << "pos = " << pos << std::endl;
      std::cout << "weight = " << weight << std::endl;
    }

But I only get non-zero values in the range [-35, 35]:

pos = [-35]
weight = 9.87711e-267
pos = [-30]
weight = 3.69388e-196
pos = [-25]
weight = 1.91856e-136
pos = [-20]
weight = 1.3839e-087
pos = [-15]
weight = 1.38634e-049
pos = [-10]
weight = 1.92875e-022
pos = [-5]
weight = 3.72665e-006
pos = [0]
weight = 1
pos = [5]
weight = 3.72665e-006
pos = [10]
weight = 1.92875e-022
pos = [15]
weight = 1.38634e-049
pos = [20]
weight = 1.3839e-087
pos = [25]
weight = 1.91856e-136
pos = [30]
weight = 3.69388e-196
pos = [35]
weight = 9.87711e-267
pos = [40]


When the radius is 512 I thought that the bell curve would have
support in the interval: [-512, 512] but it seems that the radius in
the gaussian expresses something else.