public TouchscreenCalibrator(int kx1, int kx2, float kx3, int ky1, int ky2, float ky3)
{
Calibration = new TouchscreenCalibration
{
Kx1 = kx1,
Kx2 = kx2,
Kx3 = kx3,
Ky1 = ky1,
Ky2 = ky2,
Ky3 = ky3
};
}
/// <summary>
/// Calculates the translations required to map points from the reference point set to the sampled point set
/// </summary>
/// <param name="calibrationSet">A map of reference device coordinates to the corresponding sample point</param>
public void Calibrate(Dictionary <PointF, PointF> calibrationSet)
{
if (calibrationSet.Count < 3)
{
throw new ArgumentOutOfRangeException(nameof(calibrationSet), calibrationSet.Count,
"Insufficient number of calibration points, at least 3 required");
}
var samplePoints = calibrationSet.Values.ToList();
var referencePoint = calibrationSet.Keys.ToList();
var numPoints = calibrationSet.Count;
var a = new float[3];
var b = new float[3];
var c = new float[3];
var d = new float[3];
if (numPoints == 3)
{
for (var i = 0; i < 3; i++)
{
a[i] = samplePoints[i].X;
b[i] = samplePoints[i].Y;
c[i] = referencePoint[i].X;
d[i] = referencePoint[i].Y;
}
}
else
{
for (var i = 0; i < 3; i++)
{
a[i] = 0;
b[i] = 0;
c[i] = 0;
d[i] = 0;
}
for (var i = 0; i < numPoints; i++)
{
a[2] = a[2] + samplePoints[i].X;
b[2] = b[2] + samplePoints[i].Y;
c[2] = c[2] + referencePoint[i].X;
d[2] = d[2] + referencePoint[i].Y;
a[0] = a[0] + samplePoints[i].X * samplePoints[i].X;
a[1] = a[1] + samplePoints[i].X * samplePoints[i].Y;
b[0] = a[1];
b[1] = b[1] + samplePoints[i].Y * samplePoints[i].Y;
c[0] = c[0] + samplePoints[i].X * referencePoint[i].X;
c[1] = c[1] + samplePoints[i].Y * referencePoint[i].X;
d[0] = d[0] + samplePoints[i].X * referencePoint[i].Y;
d[1] = d[1] + samplePoints[i].Y * referencePoint[i].Y;
}
a[0] = a[0] / a[2];
a[1] = a[1] / b[2];
b[0] = b[0] / a[2];
b[1] = b[1] / b[2];
c[0] = c[0] / a[2];
c[1] = c[1] / b[2];
d[0] = d[0] / a[2];
d[1] = d[1] / b[2];
a[2] = a[2] / numPoints;
b[2] = b[2] / numPoints;
c[2] = c[2] / numPoints;
d[2] = d[2] / numPoints;
}
var k = (a[0] - a[2]) * (b[1] - b[2]) - (a[1] - a[2]) * (b[0] - b[2]);
Calibration = new TouchscreenCalibration
{
Kx1 = ((c[0] - c[2]) * (b[1] - b[2]) - (c[1] - c[2]) * (b[0] - b[2])) / k,
Kx2 = ((c[1] - c[2]) * (a[0] - a[2]) - (c[0] - c[2]) * (a[1] - a[2])) / k,
Kx3 = (b[0] * (a[2] * c[1] - a[1] * c[2]) + b[1] * (a[0] * c[2] - a[2] * c[0]) +
b[2] * (a[1] * c[0] - a[0] * c[1])) / k,
Ky1 = ((d[0] - d[2]) * (b[1] - b[2]) - (d[1] - d[2]) * (b[0] - b[2])) / k,
Ky2 = ((d[1] - d[2]) * (a[0] - a[2]) - (d[0] - d[2]) * (a[1] - a[2])) / k,
Ky3 = (b[0] * (a[2] * d[1] - a[1] * d[2]) + b[1] * (a[0] * d[2] - a[2] * d[0]) +
b[2] * (a[1] * d[0] - a[0] * d[1])) / k
};
}