public static Point3D FindCenter(ICurve[] curves)
{
var compCurve = new CompositeCurve(curves, 0.001, true);
var lis = new List <Point3D>();
var l = compCurve.Length();
lis.AddRange(compCurve.GetPointsByLength(l / 69)); // nice.
var x_mean = Math.Round(lis.Average(p => p.X), 3);
var y_mean = 0.0;
var z_mean = Math.Round(lis.Average(p => p.Z), 3);
return(new Point3D(x_mean, y_mean, z_mean));
}