Loft problems

Hello everyone, I’m trying to generate a complex surface lofting a set of curves:

It’s the same curve that I deformed, and it gets repeated along two spirals.
The problem I have is that when i generate the loft, I get this result:

The first part of the curve is the same, It doesn’t change until the little “roof”, but on the surface, I get a weird twist.
I tried rebuilding the curves, but I get the same problem.

Anyone knows what else can I try? I attach the rhino file just in case.
Thank you very much!
Loft.3dm (85.8 KB)

Sweep2 is worst:

Hi Alejandro - you can get an idea why this is if you look at the distribution of the control points relative to the shapes of the curves - here you see 15 points selected on each curve-

Loft will want to line up the parameters of the curves, it does not much care about the shape. I think I’d stick with the original edited curves (these look like they are rebuilt, maybe?), if they are all the same points and degree, and try to make the points on the shapes correspond. RebuildCrvNonUniform may also help in a case like this.


Hi pascal, thanks a lot for your answer!
I did what you recommended, and now the two different curves have the same amount of points and on the same position where I could. The resulting loft is much better, but I still get a problem when it goes from curve to curve, here:

Any suggestions?
loft2.3dm (331.8 KB)
thanks a lot again!

Hi Alejandro - see the attached - I used InterpCrv (knots=Uniform, in this case I would say) to ‘connect’ the parts of the curve that should be connected, according to my guess. Quad and Near Osnaps are useful here. Then, NetworkSrf. The advantage, in this case, of NetworkSrf is that it does not care about curve structure like Loft, so you can draw your shape curves any way that makes sense for the shape, and not worry about matching up the control points.

loft2_Network.3dm (200.5 KB)


An alternate approach for this would be to draw additional interpolated curves using Near Osnaps as shown in the attached file. InterpCrv is the command for this type of curve. Then use NetworkSrf. Any better?
NetworkSrf.3dm (91.3 KB)

Thanks a lot Brian and Pascal, that’s perfect!