/// <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);
    }