Double iso curves

I ran into issues with a loft surface. In u-direction got double iso curves. How can I avoid this? A change in tolerances did not improve the situation.

thats usually depends on your curves, if they are broken in several parts or if they have a higher density. the only way to avoid this is keep them as simple as possible.

Hi Salamander - hard to say without seeing the curves and knowing what command made the surface, but my guess of the moment is a loft with curves that do not quite match in structure - that will sometimes show paired isos very close together.


Thank you guys for your replies.

In the meantime I have achieved a slightly better result with adjusted curves and different loft mode.
However, the flow of iso-curves is not nice with this. I think I will stay with my first attempt.

Hi Salamander - if you can post the curves, it is at least possible someone will come up a helpful thought.


I’m not sure how to attach files. So you can download the example from my

Hi Salamander - for smooth, sort of amorphous shapes like this, I’d generally make simple curves - I’d say that they can be simpler than the ones in my attached file, with a bit of care - that all match each other exactly, and loft from these. You can make one curve, usually the most complex, and then copy it and modify the copies for the other shapes. What I did here was draw the longest curve more or less matching your original (locked) and then used

-Rebuild > SelectMasterCurve

on the other two, using my first curve as the ‘master’ - this ensures that the two curves will be rebuilt to match it. I did not, in this case, need to modify these two curves after rebuilding.

At any rate the goal is to get a) the shapes right and b) the curves matching in structure for Loft to deliver the cleanest surface.
Loft_slmndr_PG.3dm (152.5 KB)


Pascal, thanks for the help. This looks much better than my attemps.