Jagged surface with loft

Rhino Rhino for Windows
1

Hello.
I have created a solid by lofting between undulating catenary curves and their offsets.
When i visualize in arctic mode or zebra mode i get a very weird result, and not what i expected. Is this a bug, a geometrical inevitability, or something that could be easily solved?

I attached the images and filejagged_surface.3dm (669.3 KB)

jagged_surface_arctic
jagged_surface_arctic.png1173×664 280 KB
jagged_surface_zebra
jagged_surface_zebra.png1072×626 251 KB

2

between undulating catenary curves and their offsets.

How did you make the catenary curves? They are default to Polyline output, if you kept it as Polyline output that would explain the jaggedness. If you happened to switch it to smooth then it could be that the catenary curves have very dense control point spacing which may require you to increase your render mesh resolution to see things smoother or rebuild / fit the curves to be simpler control points.

3

The surfaces are pretty dense (not made from polylines though) and the Rhino standard mesh settings do not seem to be doing very well with it - as is sometimes the case with surfaces that have a long, thin UV structure… I used the following custom mesh settings to clean it up:

image

If you set the Zebra to that as well, you will see it gets much smoother.

4

Thank you both for your prompt replies. @Helvetosaur 's suggestion worked really well in the arctic mode - less so in the zebra, but it’s passable.Danke

5

You can play around with the settings, it may get better if you set a maximum edge length (something logical for your object) or lower the aspect ratio some more… Upping the grid quads (by powers of two) can also sometimes help.

6

I would still run your curves through at least the FitCrv command first before lofting to see if that doesn’t help (or if you can spare to be a little less accurate in catenary shape, rebuild command with lower control points).

7

I think you’re right about rebuilding the curve, as a matter of principle, and i did rebuild it to a 3rd degree curve with about a quarter of the original point count.
however, the resulting render mesh still looks jagged if i don’t adjust the mesh display setting.
I think @Helvetosaur is right about the render engine having trouble with very disproportionate uv spans.
Cheers!

8

I think @Helvetosaur is right about the render engine having trouble with very disproportionate uv spans.

well to be fair, I did suggest the render mesh as well. How did FitCrv work?