Pull a surface edge to curve..?

Hi All,

Is there a way to pull a trimmed surface edge to a curve… . ?

My work around is to convert the surface to a mesh then a tspline then pull t spline edge to curve then convert tspline to rhino srf… but that is a loong work flow…

Any other ideas would help greatly! thanks,

How was the original surface made?

Are both edges at the problem corner trimmed edges?

Can the other edge at the corner change shape?

Can you post a .3dm file with the surface and curve?

Hi David,
Thanks for the reply,

I uploaded a 3dm so you can see how it was made. The srf was made using network. The other edges cannot change.

Thanks!srf to curve.3dm (955.4 KB)

Which curve should the surface corner be on? Since the curves do not intersect it can’t be on both.

You need to handle this with the overbuild method. Build large surfaces then trim them back. Keep things simple and clean so surfaces can be easily matched. N-gon surfaces with patches should be avoided.

Hey David,

The yellow highlighted srf edge should be matched to the red curve in a perfect world.

Yes sir, thats how i built this, but the down fall is you dont have much control over the curvature of the surface. You kinda just get what you get and move forward. Im trying to get to the next level.

The corner of the cannot be on the blue curve if the yellow edge is on the red curve. That’s due to the geometry, not Rhino. The red and blue curves do not intersect. Which curve do you want the surface to be on?

ok i understand. The yellow srf edge needs to be on the red curve. Im not too worried about the blue curve. The geo will change once the srf edge is matched to the red curve. . If its possible to match it.

generally you cant match a trimmed surface to a curve you can only rebuild it with new curves. and you also have to decide how the curvature of the surface should loook like. just pulling it over does not define that. well somehow but not really…

maybe i also dont understand fully but to me it seems you made such a precise job with all the oval curves describing those underpants or modern Chastity belt (sorry to me it looked like one :smiley: ) and then you just want to pull one side of a surface over? why not describing the geometry new and rebuild it? maybe with a new oval or does the blue curve have to stay where it is?

Haaa… underpants…

The reason for moving the srf edge to the red curve is so the model can be more exact, just like the oval. The surface curvature will change slightly but thats ok.

Rebuild the curves so that they intersect, then build a new surface. Trying to modify the existing surface will probably result in problems in the future. After you have the revised curve(s) let us know if you need help on creating a surface through those curves.

Hi guys,

Hope someone could help with a similar issue. I’d like to move the edge of the surface highlighted yellow to the red line. That is, I’d like to transform the surface so the the yellow edge matches the red line and the remaining edges of the surface stay where they are. Is this possible? The surface was built via a network of curves, rebuilt so that the isocurves form a rough 1x1m grid and then trimmed. File: RF.3dm (8.9 MB)


Hello - at the far right of your image, I do not see how you think the result ought to be… but, here is what I think I’d try: Draw the exact edge curve exactly as you want it, all the way around - that will at least force you to make some decisions - then use Patch on that new outline, with the existing surface set as a "Starting surface’ in Patch.


1 Like


Thanks for the solution and quick response!

Is it possible to increase the surface U and V spans to more than 255?

File: RF.3dm (7.8 MB)