public static List <Point> GetIntersectionPoints(List <Line> lines1, List <Line> lines2)
{
return((from line1 in lines1
from line2 in lines2
where line1.Intersects(line2)
select LineHelper.CalculateIntersectionPoint(line1, line2)
into intersectionPoint
where intersectionPoint.X != 0 || intersectionPoint.Y != 0
select intersectionPoint).ToList());
}