/// <summary>
/// Generate the gradient maps from the previously generated height maps
/// </summary>
public void GenerateGradientMaps()
{
// compute center-point gradient
dh = h.Gradient();
absGradient = dh.AbsoluteValue();
dhdx = dh.x();
dhdy = dh.y();
AbsGradientMap = TextureGenerator.TextureFromMatrix(absGradient);
GradientMap = TextureGenerator.TextureFromMatrix(dh);
}