A method of forming a combined feature boundary based on boundaries of first and second overlapping features includes dividing the boundaries of the first and second overlapping features into line segments of known shape, identifying crossing points formed by the line segments, calculating parametric coordinates of the crossing points, and determining a sequence of crossing point evaluation based on the parametric coordinates. The method also includes calculating a first cross product based on the line segments forming a first crossing point in the determined sequence, and choosing a first path of the combined feature boundary according to a mathematical sign of the first cross product, the first path extending from the first crossing point to the second crossing point in the determined sequence. The method further includes calculating a second cross product based on the line segments forming a second crossing point in the sequence, and choosing a second path of the combined feature boundary extending from the second crossing point according to a mathematical sign of the second cross product, wherein the combined feature boundary includes the first and second crossing points and portions of at least one of the first and second feature boundaries defining the first and second paths.