SurfacePlotDemo: Points set to Double.NaN cause view cutted

I am trying to change the SurfacePlotDemo in which I want to not show a portion of the Points of the Rectangular Mesh. I tried to set the Points to Double.NaN and I can see the surface without the points but the view looks like cutted. The points that I want to exclude are excluded correctly, but the view seems to be cutted at some view angles.

If I rotate the camera the surface is shown correctly


Here is the code

  public Point3D[,] CreateDataArray(Func<double, double, double> f)
        {
            var data = new Point3D[Rows, Columns];
            for (int i = 0; i < Rows; i++)
                for (int j = 0; j < Columns; j++)
                {
                    var pt = GetPointFromIndex(i, j);
                    data[i, j] = new Point3D(pt.X, pt.Y, f(pt.X, pt.Y)*10);

                    if (i >= 0 && i < 10 && j >=0 && j < 100)
                    {
                        data[i, j] = new Point3D(double.NaN, double.NaN, double.NaN);
                    }

                }
            return data;
        }

I am doing this on Windows 10 64bit, if I try on Win7 32 bit the cutting doesn't happen.

Questions:

Is setting points to NaN the correct way to not create parts of the regular mesh?

Are there any instructions to avoid this cutting?

Regards

Marco