How to lay a NURBS surface on a polysurface?

Hi everyone, this is my first post here, please excuse me in advance if my issue seems trivial to you.

I drew a shape composed by two joined trimmed surfaces, but would need it to be a single trimmed surface (because I have to relax it).
I think it would be possible by creating a new surface and trying to move manually every point untill the surface is laying down on the polysurface.

But is there any way to do that automatically ?

Thank you in advance !

Hello - please export the surfaces to a new file and post it here - someone will have a look.


Hello Pascal.

Thank you, here it is !

test srf.3dm (116.9 KB)

Hello - here is a test… I did the ‘relaxing’ myself, arbitrarily, I’m sure it is not what you want. It is a somewhat convoluted process but, depending on your needs and constraints, possibly workable…

test srf_Maybe.3dm (179.5 KB)

This one is ‘unrelaxed’
test srf_Maybe_Unrelaxed.3dm (137.9 KB)


Thank you Pascal. Did you do that manually ?

Here is a clip - it’s large, I do not know if it will upload.

Nope - too big - hold on, I’ll see if I can chop it a little.

@jean-christophe.boss - this one uploads OK - see if that helps for what you need.



@pascal Your method of creating a starting surface and using Patch is what I’d do.

I try to make it for my own practice.
test srf.3dm (2.6 MB)

After EdgeSrf, when I want to keep the number of surfaces as 1,
I might do like this but I’m not sure if this is the correct way.

I know the Pascal’s method after I had created my 3dm. Pascal’s method is better.

Or If I want to reduce control points as much as I can, and if it is ok to increase the number of surfaces, I do like this.

Or like this.

Hello everyone, thank you so much for your help, especially Pascal for your video !
This helped me a lot !