I'm struggling since 3 years about that issue, maybe someone can help about it;

As you can see down below i have kind of vortex shape (surface) and would like to extract u and v isolines as polyline or spline for that extractisoline command just giving random splines, xedges command giving only top and bottom circles, if i convert that shape into mesh it's giving distorted mesh body, i can't also snap intersection of isolines to drawing with 3dpoly, i have no idea left can someone tell me what can i do more?

I just need exact position of isolines itself or intersection points.

Note: I found that script many years ago but won't work either!
Script:https://adndevblog.typepad.com/autocad/2014/03/extracting-isolines-from-surface.html

Thank you and Best Regards

Extractisoline=surfextractcurve I already tried that command but it's giving me random lines on surface, i need isolines precisely as shown as on model or at least their intersection points, in anyway i can't snap of this isolines this is the real problem! Nevertheless thank you very much for your respond Vladimir

Cheers

In other words, if you want to extract curves, do it on a real 3D solid.