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// Geometric Tools, LLC
// Copyright (c) 1998-2010
// Distributed under the Boost Software License, Version 1.0.
// http://www.boost.org/LICENSE_1_0.txt
// http://www.geometrictools.com/License/Boost/LICENSE_1_0.txt
//
// File Version: 4.10.0 (2009/11/18)
#include "Wm4FoundationPCH.h"
#include "Wm4ApprGaussPointsFit2.h"
#include "Wm4Eigen.h"
namespace Wm4
{
//----------------------------------------------------------------------------
template <class Real>
Box2<Real> GaussPointsFit2 (int iQuantity, const Vector2<Real>* akPoint)
{
Box2<Real> kBox(Vector2<Real>::ZERO,Vector2<Real>::UNIT_X,
Vector2<Real>::UNIT_Y,(Real)1.0,(Real)1.0);
// compute the mean of the points
kBox.Center = akPoint[0];
int i;
for (i = 1; i < iQuantity; i++)
{
kBox.Center += akPoint[i];
}
Real fInvQuantity = ((Real)1.0)/iQuantity;
kBox.Center *= fInvQuantity;
// compute the covariance matrix of the points
Real fSumXX = (Real)0.0, fSumXY = (Real)0.0, fSumYY = (Real)0.0;
for (i = 0; i < iQuantity; i++)
{
Vector2<Real> kDiff = akPoint[i] - kBox.Center;
fSumXX += kDiff.X()*kDiff.X();
fSumXY += kDiff.X()*kDiff.Y();
fSumYY += kDiff.Y()*kDiff.Y();
}
fSumXX *= fInvQuantity;
fSumXY *= fInvQuantity;
fSumYY *= fInvQuantity;
// setup the eigensolver
Eigen<Real> kES(2);
kES(0,0) = fSumXX;
kES(0,1) = fSumXY;
kES(1,0) = fSumXY;
kES(1,1) = fSumYY;
kES.IncrSortEigenStuff2();
for (i = 0; i < 2; i++)
{
kBox.Extent[i] = kES.GetEigenvalue(i);
kES.GetEigenvector(i,kBox.Axis[i]);
}
return kBox;
}
//----------------------------------------------------------------------------
//----------------------------------------------------------------------------
// explicit instantiation
//----------------------------------------------------------------------------
template WM4_FOUNDATION_ITEM
Box2<float> GaussPointsFit2<float> (int, const Vector2<float>*);
template WM4_FOUNDATION_ITEM
Box2<double> GaussPointsFit2<double> (int, const Vector2<double>*);
//----------------------------------------------------------------------------
}
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