GRD2HESS_BASE - Base function for GRD2HESS.

Contents

Syntax

      [gxx, gyy, gxy] = ...
  GRD2HESS_BASE(gx, gy, rho, int, hsize, samp, tn, thez, sigt);

See also

Ressembles: GRD2HESS. Requires: GRDSMOOTH_BASE, SMOOTHFILT_BASE.

Function implementation

function [gxx, gyy, gxy] = ...
    grd2hess_base(gx, gy, rho, der, int, hsize, samp, tn, thez, sigt)

[gxy,gxx] = grdsmooth_base(gx, 0, der, hsize, 'ij');
gxy = -gxy;
[gyy,gyx] = grdsmooth_base(gy, 0, der, hsize, 'ij');
gyy = -gyy;
gxy = (gxy+gyx) / 2;

gxx = mean(gxx, 3);
gxy = mean(gxy, 3);
gyy = mean(gyy, 3);

if tn
    nn = gx.^2 + gy.^2;
    nn = sqrt(eps+nn);
    gxx = gxx ./ nn;
    gxy = gxy ./ nn;
    gyy = gyy ./ nn;
end

compute the direction of smoothing (along edges) in the anisotropic case

if any(strcmp(int,'ani'))
    theta = mod(atan2(mean(gy,3),mean(gx,3)),pi);
else
    theta =[];
end

perform tensor smoothing: isotropic (classical) or anisotropic (improved) spatial averaging of the tensor and of the directional derivatives

if rho~=0 && ~(islogical(int) && ~int)
    gxx = smoothfilt_base( gxx, rho, int, hsize, samp, thez, sigt, theta );
    gyy = smoothfilt_base( gyy, rho, int, hsize, samp, thez, sigt, theta );
    gxy = smoothfilt_base( gxy, rho, int, hsize, samp, thez, sigt, theta );
end

end % end of grd2hess_base