can i do this in rhino?

i have a feeling this is either very easy, or it simply can’t be done. is there any way in rhino to make a simple minimal surface defined by a single non-planar edge curve? non of the surfacing tools seem to apply.

Do you want to fill the upper or lower half of that outline?

I don’t use Rhino, but most of the tools and techniques I use in Alias are similar. It seems that you don’t have enough data to define the surface. If it’s across the top, the only topology you’re going to get is planar along the top four points and some sort of rounded rectangular blend around the edges. Along the bottom, those curves can define something like a star shape with its points folded up.

I think you’d be better off making a curve network or something and filling it in that way. Put in some more guide curves, even if they seem redundant, and work from those.

yes, i’m trying to create the surface on the upper half, with the point being the apex of a tent-like structure.

i just finished making a curve network, but rhino is having trouble making a surface from such a complicated network. maybe it’s about time i started to use Alias.

you’ll have the same problems using Alias.
I don’t believe you have enough geometry to define what you’re looking for.
Have you sketched and THOUGHT through what your surface will look like? or you just hastly imagined it and put the burden of figuring it out on your software? (I often see this mistake when people can’t do a surface they want).

You won’t be able to do Network curves since that’s not how it behaves.
you can probably do it from all the diagonal lines (from the top view) but without incluing the outline shape.

I see you have a flat square at the top. do you WANT it to be a square? or were you looking for a circle?

For a QUICK FIX try PATCH command with default settings (1,10,10,1 adjust trim and tangency).
This IS NOT a final solution, because again, the computer did all the thincking. it may however be ok for a concept presentation.

Have you sketched and THOUGHT through what your surface will look like? or you just hastly imagined it and put the burden of figuring it out on your software?

i know what you mean, (i gather you’re not of the frank ghery school of “design it first, worry about how to build it later”) but i’m new to all this cad stuff. the patch command was exactly what i was looking for, worked perfectly. i understand the need to model geometry cleanly, but why should the resultant surface not be considered a final solution? it produced the surface i had in mind.

If it produces the surface you want, perfectly, then you’re probably okay. The place you lose out is editability, and complete control over the little nitpicking details…
I remember trying to model a specific knife blade once. I tried several different methods of creating the edge surface, and at first glance simple patch and fill-surface tools seemed to be working fine…until I tried to edit them. Strange trim points, weird isoparms, etc. I ended up using a completely editable, trimmed skin-surface, which worked nicely.

Patch is a “legal” way of making a surface like that, so if works, go ahead. If you want more control, then you could probably most easily just simplify it and tweak it by hand. Probably eventually Patch will be hooked up to History(if it’s not already in the Beta)so you’d be able to make a few input curves then edit them.

Preferably, I would make a larger, untrimmed, rectangluar surface–generally with NURBS you want to think like you’re fabricating it out of sheetmetal…–then Trim out the shape you want. If it doesn’t quite align with where you want the edges to go, then it is possible–though tricky to get a good result without changing the whole shape too much–to use Patch, with the surface you’ve made as the input surface, to get it closer.

Patch works well if you split your curve into 4 at each petal tip.