[Insight-users] Boundary nodes for cubic BSplineDeformableTransform?

[motes motes]

I have asked this question before but it still seems to cause me
problems. From the theory of BSplines at most k k-order basisfunctions
are non-zero:

http://cse.taylor.edu/~btoll/s99/424/res/mtu/Notes/spline/bspline-property.htm

A cubic basisfunction has order k=4 where order = degree+1. Which
means that at most 4 cubic bspline basisfunctions are non-zero.

In ITK I have declared a 2D BSplineDeformableTransform like this:

....
....
    // Specifying the degree not the order!
    typedef itk::BSplineDeformableTransform<double, 2 , 3>
BSplineTransformType;
    typedef typename BSplineTransformType::RegionType           RegionType;
    typedef typename BSplineTransformType::SpacingType          SpacingType;
    typedef typename BSplineTransformType::OriginType             OriginType;
    typename BSplineTransformType::Pointer transform =
BSplineTransformType::New();
    typename FixedImageType::RegionType fixedRegion =
imageF->GetBufferedRegion();
    RegionType bsplineRegion;
    typename RegionType::SizeType gridSizeOnImage;
    typename RegionType::SizeType gridBorderSize;
    typename RegionType::SizeType totalGridSize;

    // B-spline stuff
    gridSizeOnImage.Fill(5);
    gridBorderSize.Fill(3);    // Border for spline order = 3 ( 1
lower, 2 upper )
    ....
    ....