Advice: Best practice in creating surface with planar edges?

In creating a surface with slight curve looking from front and right view,
what would be a good approach?

Hi Toshiaki - is the perimeter curve planar?
edit (Answer: Yes, read the subject…)


yes the perimeter is planar.
I’ll check out the link. Thanks!

Hi Pascal,
Can’t seem to get the edges of the surface produced by patch to
meet up with the original perimeter curve…
Sorry not to mention in beginning, I also wanted the edge of the
created surface to be planar.

patch.3dm (153.7 KB)

Hi Toshiaki - Well, yours is pooched up rather more than my example. I guess the idea is to have the surface planar enough to Cap on the bottom side, right?

I’d still be tempted to use Patch with a starting surface here with the straight edges and sharp corners, but a loose loft can also make this kind of shape, it just does not lend itself to this hard ‘arcs and straights’ shape all that well. I’ll see if I can cook up an example.

I guess, if I understand the shape you want I’d patch the curves with a good number of spans - 30 or 40 each way. Then untrim the result (or don’t ask for automatic trim in Patch) and then trim/split the result with a level line or plane. The result will have a planar perimeter and should come pretty close to the original perimeter.



Perhaps I don’t understand the question, but here is the result using your lines joined in a particular way and Network Surface. The outside edges are planar and will cap into a solid.

Hi Pascal,

I’ll try to bump up the UV to see how it goes.
Thanks for the tip!

Make sure the distance between the points which Parch generates for fitting the surface are closer together than the distance between control points on the surface. Something like 3 or more patch points per control point spacing would be good.

Also, the Stiffness in Patch can have a significant effect. Experiment with different values. For this you may want a value of 100 or so.

Hi OSTexo

I’m trying to get a all around soft curved surface.
Basically what patch is doing is great, but also want the edges to be able to be capped.
sort of railrevolve with two guiding curves I guess…

Actually your Networksrf looks nice. Can you teach me the steps?
I couldn’t get it to go smoothly all around…
Using networksrf I end up with something not smooth or get a flattened corner&not smooth.

Thanks! I’ll check out the stiffness.
I only changed them when adjust tangency is set on.


Please see attached images. I joined the curves indicated by the common colors, selected all curves and ran the network surface command. The last image is what I was left with. I see your point about the surface flattening at the rounded corners, I’m wondering if additional guide lines or different positioning of those guide curves would improve that even more. I’ll do some more testing over the next few days to see if I can come up with something.

Thanks for the explanation. I’ll try it out!

At first I was hoping this kind of surface was a bit more easier to make and a common one…like surface on buttons, smartphone back, soap dishes, etc…

Trying out railrevolve then adjusting points…
seems ok here, but can’t control much…
(and more flattened version for now…)

railrevolve_then_adjustingpts.3dm (125.1 KB)

eh… curve with more height railrevolve doesn’t seem to work too well.

@OSTexo @pascal
Hi both,

If you can help out again…

I’m still trying to work on the soft round surface…
I guess I’m aiming for front of macbook, so a smooth surface all around that joins with a hardedge.
I guess samsung galaxy backside maybe(I don’t own it though…)

Trying different ways to make it, but I can’t get the corner right.
Closest I came so far is using a using sweep2 in the end. But still I get some bumps…

Others are a mess…

For the patch… I’m seem to not be handling it well… I also face problem closing up the surface too…

Round_soft_surfaec.3dm (1.0 MB)

Hi Toshiaki - I’d built is something like this, not a surface but several, (I did not understand that from your original post).

Round_soft_surfaec_PG.3dm (98.4 KB)

Updated the file… I noticed I had not made the outer edges tangent to the vertical edges like the curves are.

BTW, looking at your base shape - I notice that the corner has a slight flattening of the curvature in the middle - I’d say to maintain really nice visually smoothly-progressing lines, there should only be one acceleration in curvature with maximum curvature in the middle, rather than two max curvatures - a small difference but it looks cleaner when reflections and light fall on it.


Thank you pascal.

Yes, when I was writing my original post I didn’t have a clear way of explaining what I wanted…

The explanation of the curvature really helps.
Getting more understanding of curvature of curves and how it affects the outputted surface
with different tools seems to be my next steps.

hi Pascal,

For the doc which you attached, just to double check,
could you explain the process order?
Is it,

  1. sweeping the curve to get a big surface,
  2. Trim to make the round edge in the surface
  3. split edges so there would be three edges both in the surface side and frame
  4. blendsrf straight edges x 2 (wasn’t sure since your surface here looked very simple)
  5. and last do a sweep2 in the corner?

Similar question of making a soft round surface… but with the frame being like a kidney shape.
Having trouble making the first large surface to work from…
I tried a sweep all around by using a short split reference curve,
but of course I get overlap…
tried couple of other ways but couldn’t figure it out…

Soft_Round_Surface_edgesgoingin.3dm (161.2 KB)

Hi Toshiaki - for this new shape, I’d be inclined to use the ‘loose loft’ technique - see the attached file - if that is more or less what you have in mind, I’ll describe the process. Tomorrow…

Soft_Round_Surface_edgesgoingin_PG.3dm (207.9 KB)



I’m not sure that surface is as simple as it seems to be, particularly if your aim is an Apple like surface. I was able to get something that looked decent with a decent higher continuity, but I’m curious to see if I could actually build out a much larger surface and do some specific point editing to model that very gradual surface you seem to be looking for. I’ll think about it some more and let you know what I come up with anything that is a possibility.

Thank you for the file pascal.
I didn’t know loft can be used this clean starting from the point.

Trying it out.
Trying_Soft_round_surface.3dm (218.9 KB)