Surfacing commands which don`t need rebuild to get clean results

I would like to ask some basic questions.

I learn and read a lot of things related to surfacing in Rhino with using class-A and modeling techniques with single-span surfaces and smooth geometries with a nice continuity (mostly in product design and automotive design).

Please tell me which surfacing commands will give me geometry based on curve control points without the need to rebuild of surfaces (without adding more control points than initial curves have)? Or maybe should I always rebuild all surfaces after surfacing commands even if my curves are clean and single-span (except edgesrf which already give good results)?

As far I know sweep and blendsrf are based on the same engine and need a rebuild after that (or maybe I`m wrong). Edgesrf gives me exact results as the good curve is (horizontal and vertical). Rest needs rebuild (loft partially because it creates good result in one direction). Do I miss something?

Is there any more command which will give a clean result with single-span initial curves without rebuilding surfaces after or should I rebuild every surface (rebuild and rebuildUV commands) after surfacing from clean single-span curves to get single-span surfaces?

There is also the possibility to matchsrf after rebuild surface to get continuity without gaps with the same UV structure if it holds enough control points.

Is there something more on that topic?

This is an open question so I don’t have any specific example in my mind. I try to understand which commands should I use and which don’t. I try to also judge which commands are worth to use even if they have a complex structure to rebuild them after. Which rebuild should I use in which cases? I`m sure it’s a repeatable process and I try to dig it in.

Any help appreciated. Sorry if I`m messing something.


the only ones that i could think of now which actually dont create surfaces which correspond in that sense directly to the input curves would be Patch and NetworkSrf. all others if set correct for instance loft as you said but also Sweep1, Sweep2, EdgeSrf and BlendSrf will create surfaces which will have the same degree and cp. but if you mix curve degree and cp then you will of course have to rebuild the outcome.


Maybe I mixed curve degree and that`s why I had more cp in final surfaces. Now after you reply I feel stupid that I haven’t found it earlier. It’s obvious. Thanks a lot for your answer.

@mdesign I suggest you taking a look at these great videos made by Skyler Greenwalt @sgreenawalt


Having the possibility of explicit control over degrees/spans in all surface creating commands would make a lot of things so much easier.
@Pascal can you put this into the wishlist for Rhino 8?


Added to the discussion-pile for V8.



What does that mean? Essentially a built in version of Rebuild? Deviation of the surface from the input objects, perhaps significant deviation, would have to be acceptable unless the the degree and number of spans which can be selected is restricted.

Yes exactly this.
A built in version of rebuild with control over degree and span count.
Of course a deviation indication would be needed for this to be useful.
If no such explicit control is needed an “automated” option could use the already existing method.
By the way, rebuild itself could use this too.
Essentially, I would like to have similar control over degree/spans as for instance in Alias:

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The deviation indication should be prominent. Otherwise many users would assume somehow (mathematical magic?) the single span version exactly matches the multispan version.
Sweep2 for example allows rebuilding of cross section curves with a specified number of control points and there is no indication of deviation. I wonder how frequently users have had problems because of that.

Hi David - deviation from the non-simplified version, you mean, right?


I guess he means deviation from rail curves/edges?
In general, what else can theses surfaces deviate from if not input curves?
Maybe a reference mesh.
But this would have to be an input to the surface command to be relevant.

Yeah, but that should not be affected by the cross-sections - which made me wonder… Eventually I’ll need to convey the right thing to the typists…


Sorry, Pascal.
I edited my post while you were already responding…

Sweep2 provides no numerical indication of deviation from the input curves when they are rebuilt. If the deviation is large enough the user may notice it in the preview if they are aware it can happen. However the deviation may be small enough not to be noticed but larger than the absolute tolerance and cause problems with subsequent Join operations, etc.

Makes sense 100%.
Might as well include edge conditions (if the surface command permits, e.g. sweeps) to make it complete.

Got it, thanks.


Thanks for reminding this feature. I`ve watched many Alias tutorials lately and that thing caught my eye :slight_smile: It would be so awesome to get that in Rhino.

I know this series. I watched this series one month ago but after your reminding, I started it again. I hope to see more movies like this. Those movies are my favourite about surfacing in Rhino. After this movie series, I realised how much I miss VSR plugin analysis features.

Hello Marcin,
I fully agree with you. The VSR tool was a real advancement and the best plug-in for clean and light surfaces. These tools are a great wish for V8!
With best regards, Chris

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