Ymg,
I'm sorry for not provide the points .
Thank you for check this case .
In realistic terrain , there are some steep and cliffs , I wish the contour routine can support this case .
You have also mentioned, can not handle discontinuous 3DFACE , I wish it can .
Therefore, can we change an idea to deal with the contour problem; For example, the first generation of each line segment at every elevations, and then combine them, and then fillet them .