//! Performs one step of extremum interpolation.
void interpolateStep(int r, int c, ResponseLayer *t, ResponseLayer *m, ResponseLayer *b, double* xi, double* xr, double* xc )
//void interpolateStep()
{
CvMat* dD, * H, * H_inv, X;
double x[3] = { 0 };
dD = deriv3D( r, c, t, m, b );
H = hessian3D( r, c, t, m, b );
H_inv = CreateMat( 3, 3, CV_64FC1 );
cvInvert( H, H_inv, CV_SVD ); // incomplete check after invert() => CreateSVD()
//cvInitMatHeader( &X, 3, 1, CV_64FC1, x, CV_AUTOSTEP );
InitMatHeader( &X, 3, 1, CV_64FC1, x, CV_AUTOSTEP ); //check
cvGEMM( H_inv, dD, -1, NULL, 0, &X, 0 ); //incomplete
free(&dD);
free(&H);
free(&H_inv);
//cvReleaseMat( &dD );
//cvReleaseMat( &H );
//cvReleaseMat( &H_inv );
*xi = x[2];
*xr = x[1];
*xc = x[0];
}
/**
* Interpolate the interest point to subpixel accuracy, by the method
* from (Brown and Lowe, 2002).
*
* This comes down to solving the equation Ax=b where A is the
* second-order derivative of the scale-space function shifted (i.e.
* the 3D Hessian), and b = -(dx,dy,ds). The scale-space function is
* assumed shifted so the interest point candidate is at the origin.
* The solution to this equation yields the position (x,y,s) in
* scale-space of the actual extremum.
*
* The values for the partial derivatives are approximated by point
* value differences in the response layers.
*/
void FastHessian::interpolate(Point p, ResponseLayer *b, ResponseLayer *m, ResponseLayer *t,
double *dx, double *dy, double *ds)
{
Mat X; // holds solution
Mat h3d = hessian3D(p, b, m, t);
Mat d3d = deriv3D(p, b, m, t);
d3d *= -1;
if(solve(h3d, d3d, X)) {
*dx = X.at<double>(0,0);
*dy = X.at<double>(1,0);
*ds = X.at<double>(2,0);
} else {
*dx = *dy = *ds = 0.0f;
}
}
//! Performs one step of extremum interpolation.
void FastHessian::interpolateStep(int r, int c, ResponseLayer *t, ResponseLayer *m, ResponseLayer *b,
double* xi, double* xr, double* xc )
{
CvMat* dD, * H, * H_inv, X;
double x[3] = { 0 };
dD = deriv3D( r, c, t, m, b );
H = hessian3D( r, c, t, m, b );
H_inv = cvCreateMat( 3, 3, CV_64FC1 );
cvInvert( H, H_inv, CV_SVD );
cvInitMatHeader( &X, 3, 1, CV_64FC1, x, CV_AUTOSTEP );
cvGEMM( H_inv, dD, -1, NULL, 0, &X, 0 );
cvReleaseMat( &dD );
cvReleaseMat( &H );
cvReleaseMat( &H_inv );
*xi = x[2];
*xr = x[1];
*xc = x[0];
}
