Creating topography mesh - invalid mesh

I want to make a topography mesh by using contour lines.
But the result of Delaunay is a invalid mesh.
I don’t know why the invalid mesh merge…
Thank you !!

contour mesh.3dm (1.1 MB) (25.5 KB)

Flatten the points before culling the duplicates and set it to leave one worked for me

Thank you!
It worked :slight_smile: