[Insight-users] NonUniformBSpline - ITK Version 2.6.0.

[Dan]

Hi,

 

I'm having some difficulties understanding how the "NonUniformBSpline" ITK
method works. 

The goal is to fit a second order spline through a set of 3 points as
follows:

 

const int nrPoints = 3;    

const int splineOrder = 2;

typedef itk::NonUniformBSpline <2> splineTransformation;

splineTransformation::Pointer smartEditSplineTransf =
splineTransformation::New();

smartEditSplineTransf->SetSplineOrder(splineOrder);

 

//Set input points

splineTransformation::PointType refPoint ; 

splineTransformation::PointListType  pointList(nrPoints, refPoint);

pointList[0][0] = 212.0;//OX - point 1

pointList[0][1] = 116.0;//OY - point 1

pointList[1][0] = 69.0;//OX - point 2

pointList[1][1] = 221.0;//OY - point 2

pointList[2][0] = 132.0;//OX - point 3

pointList[2][1] = 88.0;//OY - point 3

 

//Set knot points

splineTransformation::KnotListType knotPointList; 

knotPointList.push_back(212.0);//OX - point 1

knotPointList.push_back(69.0);//OX - point 2

knotPointList.push_back(132.0); //OX - point 3

smartEditSplineTransf->SetKnots(knotPointList);

smartEditSplineTransf->ComputeChordLengths();

 

In order to evaluate the spline on a number of points:

 

double nrPoints = 198.0;

splineTransformation::PointType pointOut;

for (i = 0; i < nrPoints; i++){

pointOut = smartEditSplineTransf->EvaluateSpline( ((double) i)/( nrPoints -
1.0) );

}

 

 it seems to me that I also have to input a set of control points that I
don't understand what they stand for.

 

I've also tried to make use of the method:

 

smartEditSplineTransf->ComputeControlPoints(); 

 

but with no success.

 

Your feedback would be greatly appreciated

 

Thanks,

Dan

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