Unwanted Kink in Network Surf

Hey guys, working in Rhino6 and trying to learn how to make nice smooth complex surfaces. The best method I’ve found so far to build surfaces like this one is network surf. As you can see, I’ve built the edges with curves, then added some more guide curves through it. My issue is that some of the guide curves are showing up on the surface, instead of making it totally smooth:

Do you guys have advice for how to get rid of the kink in the surface? Or do you have any suggestions for a better way to build surfaces like this?

File is attached. Any advice would be much appreciated! Thank you!

Smooth Surface Question 6.17.2020.3dm (1.3 MB)


First step should be to simplify the long curves to the extent possible. Were those curves created directly or are they they obtained from other geometry, perhaps an intersection?

Have you tried using Sweep2?

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Hi David, when you say “long curves”, are you refereing to the curves that make up the edge of the surface? These were partially taken from surrounding geometry as edge curves, and also created directly. The straight parts and circular parts were taken from surrounding geometry, while the more curved parts were drawn in 2D, moved, and connected using Blendcrv. The round curves are taken from intersections.

I use Sweep2 quite often, but most times I’ve tried to use it to create forms that are this sculptural and curvy, it doesn’t seem to come out right.

IMO you are over asking for that surface in 1 piece… why not break it up into smaller pieces, use matching control points for each edge curve to get nice single span surfaces and matchsrf to get your edges to flow? .


Hi Joel - at least part of that is coming from the bottom curve - the curve around the heel is only tangent to the next curve along, on either side.

If you want curvature continuity (and NetworkSrf will enforce this as you see, regardless of the input curves) then I would start with clean curves that are G2. You have several locations where the curves are not G2.

I would also place my ‘other’ curves where there are clear breaks in curvature or acceleration -

This way, however you go - network or multiple patches (which also seems to me like the way to go, here but it is worth seeing if NetworkSrf can get you there well enough with less pain.) the curves will be more likely set up well for the surfacing.



My opinion would be that you’re never going to get to where you want by feeding a ton of curves into NetworkSrf. Roughly speaking, each of those curves that go across your surface should be the edge of a single surface, and those surfaces should be made with something that doesn’t create overly dense point counts like NetworkSrf does. Once you create those clean surface patches, you use MatchSrf to make them all smooth relative to each other. This may not be a popular opinion around here, but I think NetworkSrf should never be used as a primary surfacing tool, ever. Also - that lip around the top edge (head tube? this feels very bike-ish) should be split off as its own patch(es). I’m currently putting together a whole video series on how to better approach problems like this:



Ok, I tried a little bit of everything you guys suggested. I started off by fixing my edge curves so that they are all G2. I then split up my edge curves to use sweep2, to build the surface patches. I built most of them with sweep2 and used Matchsrf to get them to connect smoothly. All was going great until I got to the selected surface shown here:

I ran into some major kinks with the sweep2:

When running the sweep2 I discovered that selecting, “Rebuild cross sections with 6 control points” helped to smooth out the surface, but also found that it didn’t keep the intent of my curves and caused some wobbles in the surface:

I’m trying to learn how to model the “Right” way, with clean curves and less dense surfaces. Do you guys think sweep2 is the right tool for building the surfaces? Can you suggest a way to get rid of the new wobbles in the surface? New file is attached:
Surfacing Question 6.18.2020.3dm (1.1 MB)

Thanks again, your guys guidance is truly appreciated!!


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You’re making progress for sure! I would say that the entire section that goes “concave” along the top edge of your model - all of those areas should be their own surface patch. Things get problematic when you try to combine small details like that with the design intent of the surfaces below it. I’m going to be out of the office for a bit starting tomorrow (birthday road trip!) but I’d actually be stoked to do a video on your problem/issues for my channel if you want - it ties in really nicely with a lot of the approaches I’m trying to show.

Thank you!! Here’s a 3rd attempt. I ditched the guide curve that was giving me trouble in the kinked area and split out the top lip section as you suggested. Definitely working better!

Not quite sure how to Matchsrf the new top lip section to the surface at the sides though, because the edges where they connect are different lengths.

Have a good trip! Yeah a video for your channel on these issues would be rad! Thank you!!

Surfacing 3rd attempt 6.18.2020.3dm (1.2 MB)


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The best advice: don’t use network surface.


Another option:

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I would use NetworkSrf, but I would not use the two curves in front (blue in picture).

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Nice, I’ve never seen that tool before.

Wow much cleaner. That looks great, thank you.

SubD, available for all Rhino 6 users in Rhino 7 WIP… Depending on your workflow, it might be easier to manipulate.

The good thing about Rhino is that it lets you remove icons from toolbars, so you can solve your problem by simply forgetting the existence of the “Network surface” command. :smiley: Last time I used it was several years ago.

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There should be a default Toolbar called “Advanced Surfacing” that included all tools except for NetworkSrf and Patch… and maybe a few others? Beginner users would get excited to see this “advanced” toolbar and hopefully forget about those two :smiley: