ocmath_tps_fit

1 Description
2 Syntax
3 Parameters
4 Return
5 Examples
6 Remark
7 See Also
8 Header to Include
9 Reference

Description

This function perform 2D interpolation using thin plate spline method.

Syntax

int ocmath_tps_fit(int nNode, const double *x, const double *y, const double *z, double dSmooth, ocmath_strTPS *strTPS, double* dRegularization)

Parameters

nNode: [input] the number of scatters.
x: [input] the position and the x-coordinates of each points.
y: [input] the position and the y-coordinates of each points.
z: [input] the position and the z-coordinates of each points.
dSmooth: [input] the smooth factor.
strTPS: [output] contains the interpolation coefficients of the fitting.
dRegularization: [output] the regularization factor defined by the value of dsmooth.

Return

OE_NOERROR for successful or

OE_INVALID_POINT Not enough points (n<3) or all the points are colinear;

OE_NULL_POINTER if pointer is null.

OE_INVALID_SMOOTH Parameter dSmooth should not be less than zero.

Examples

EX1

#include <wks2mat.h>
int ocmath_tps_fit_ex1()
{
        // tabulated data on a 3x3 regular grid, points of form (x,y,f(x,y))
        const int iQuantity = 9;
        double afX[] = {0.0, 0.5, 1.0,0.0, 0.5, 1.0,0.0, 0.5, 1.0};
        double afY[] = {0.0, 0.0, 0.0,0.5, 0.5, 0.5,1.0, 1.0, 1.0};
        double afF[] = {1.0, 2.0, 3.0,3.0, 2.0, 1.0,1.0, 2.0, 3.0};
        
        // resample on a 7x7 regular grid
        const int iResample = 6;
        const double fInv = 1.0/(double)iResample;
        int i, j;
        
        // no smoothing, exact interpolation at grid points
        ocmath_strTPS strTPS;
        ocmath_tps_initial(&strTPS);
        
        double dSmooth = 0.1;
        double dReg;
        
        int nRe = ocmath_tps_fit(iQuantity, afX, afY, afF, 
                                        dSmooth, &strTPS, &dReg);
        
        if(nRe)
        {
                printf("intp error  %d\n", nRe);
                return -1;
        }
        else
        {
                printf("The regularization parameter is %g\n\n",dReg);
        }
        
        // Output the results
        printf( "smooth parameter is %g\n", dSmooth);
        double x, y, z;
        for (j = 0; j <= iResample; j++)
        {
                y = fInv*j;
                for (i = 0; i <= iResample; i++)
                {
                        x = fInv*i;
                        ocmath_tps_eval(1, &x, &y, &z, &strTPS);
                        printf("%9.6f\t", z);
                }
                printf("\n");
        }
        
        ocmath_tps_free(&strTPS);
        return 0;
}

EX2

// This example demonstrates the usage of thin plate spline fitting and XY gridding.
// To test, create an Origin workshhet with three columns that contain XYZ scatters.
// The result will be stored in a newly created Origin matrix window.
#include <wks2mat.h>
void ocmath_tps_fit_ex2()
{
        int nRows = 100;
        int nCols = 100;
        
        Worksheet wks = Project.ActiveLayer();
        wks.SetSize(-1, 3);
        Dataset dsX(wks, 0), dsY(wks, 1), dsZ(wks, 2);
        
        vector vXsrc(dsX), vYsrc(dsY), vZsrc(dsZ);
        vector vXdest(nRows * nCols), vYdest(nRows * nCols), vZdest(nRows * nCols);
        
        int nSize = vXsrc.GetSize();
        
        double dXmin, dXmax, dYmin, dYmax;
        vXsrc.GetMinMax(dXmin, dXmax);
        vYsrc.GetMinMax(dYmin, dYmax);
        
        MatrixLayer ml;
        ml.Create();
        MatrixObject mo = ml.MatrixObjects(0);
        
        mo.SetNumRows(nRows);
        mo.SetNumCols(nCols);
        mo.SetXY(dXmin, dYmin, dXmax, dYmax);
        
        Matrix& mat = mo.GetDataObject();
        
        ocmath_strTPS strTPS;
        ocmath_tps_initial(&strTPS);
        
        double dSmooth = 0.0; // no smoothing, exact interpolation at grid points
        double dReg;
        
        int iRet;
        // Initialization
        iRet = ocmath_tps_fit(nSize, vXsrc, vYsrc, vZsrc, dSmooth, &strTPS, &dReg);
        
        if(iRet) {
                printf("intp error  %d\n", iRet);
                return;
        }
        
        // Create XY gridding.
        iRet = ocmath_mat_to_regular_xyz(NULL, nRows, nCols, dXmin, dXmax, dYmin, dYmax, vXdest, vYdest, NULL);
        
        if (iRet <= 0) { 
                printf("Failed to create XY gridding!\n");
                return;
        }
        
        // Interpolation
        ocmath_tps_eval(nRows * nCols, vXdest, vYdest, mat, &strTPS);
        
        ocmath_tps_free(&strTPS);
}