Trying to construct a Polycurve from two curves

So I was trying to Join the two curve in to Polycurve (in auto mode) but it keeps failing while it is successful in a similar curve, and I can’t figure out why its happening. I have tried to individually join/reverse (using list) the curves and then trying JoinPolycurve but it fails no matter what. Is there some kind of requirement that I am not aware of? I just starteed using Dynamo yesterday, so any help will be great encouragement haha.

welcome them to the community!

Use Element.Curves as in image

Is this specific to Revit? A quick google search seem to indicate that. I am using Alias actually.

It might be helpful to show the errors you’re getting.

you need to convert Alias to dynamo geometry.

Right, sorry bout that. My snipping tool just takes the focus away from my mouse and the pop up error disappears. Its says “…operation failed. Curve joined produced more than one WIRE in Polycurve”

And how do I do that?
And how did the first curve manage to join without any issues?

From what I understood, you wanted me to do this? This time I separately brought in the curves and tried to join them in dynamo, it failed with the same “…more than one WIRE…” error.

Hi Tanmaya,
Are you able to share the curves causing the issue? The error message suggests that they are not connected, and therefore can’t be joined.
In case you can’t share the curves, can you try to set a higher join tolerance, in case your two curves have a mini gap?
Cheers,
GG

:man_facepalming: Why didn’t I check for that before. It seems there was an issue with the surface and had a very small gap. I assumed wrong things about Curvature confirmed surfaces :unamused:
Lemme correct that and report back.

@Michael-GG Hey, I managed to find a workaround for another problem but I just wanted to ask what does it indicate if I get a error message saying “Could not determine the parameters of non-manifold surface.” when I was joining two surfaces using Polycurve.ByJoinedSurface

Non-manifold usually indicates that something is wrong with the surface, so it has no “legal” mathematical description, which would also usually prevent it from being visualized correctly.
In the context you mention here it could also mean that the result of connecting the two surfaces is not manifold.
Is any of the surfaces trimmed? If yes, I would check once more with an untrimmed version of the surface. If none is trimmed, I would check the aligmnent quality of the two surfaces. Do they have a gap, or overlap?
I can investigate better if you share the two surfaces.

Okay, the workaround was basically me making a complete surface (with a trim at the end) to replace the two separately trimmed surface. The trimmed surfaces were properly aligned and had tangent continuity though.

So Dynamo doesn’t like operating on two different trimmed surface that have been joined?

I would have but I have it solved for now, so just wanted to know the nuances of dynamo.

Without the surfaces I can’t tell. By the way, did you misspell the note? There is only a PolySURFACE.ByJoinedSurface note.
I could imagine that the direction of the edges of the surfaces matter. With two trimmed surfaces, that may cause issues.

Sorry, right, that’s what I meant.
Olright, I have attached the files this time.

Note - PolySurface actually successfully joins the surfaces. But then, when I use the resulting surface for operation like finding the U,V parameters of a series of points, it gives me the mathematical error. Which makes sense if you said that Dynamo doesn’t understand the mathematics behind Non-manifold surface.

Works fine for me? Which Alias version are you on?

I did already state that.
Try plotting some points on resulting surface. You might get that error.
I am on Alias 2020.3.

While this does not deliver a warning for me, it seems to produce odd results. To be honest, I’m surprised that this point at parameter returns something at all for a polysurface, as re-parametrizing a surface is a very complex issue.
Anyway, would I be right to say that what you are trying to do is to distribute points in a regularly manner over several surfaces? If so, I have been working on a general solution to this problem. I will make a video on this one in a few weeks (very busy atm).

Do you see the points in the following picture?


I wanted to find their parametric position on the surface so I could do further operations. That’s where I got the non-manifold error.
I have the problem solved because I already made a surface to replace the separate trim surfaces (and I have got another problem to solve, maybe I will open another thread for it). But you may make a youtube video because I find there aren’t many video of dynamo for alias on youtube. :slight_smile: