Curve Seam adjustment goes wrong

Hi everyone,

I sometimes come across the following odd case where “curve seam” doesnt not work as intended anymore. This is a setup for a sweep where I try to align the curve seam of the profile to the rail.
The curve closest point gives me this at 0. When I evaluate the curve at 0 the point is exactly where I want it, however when I input 0 into the curve seam, it will jump over to the “next” control point.

Usually curve seam works fine but it seems in some cases it just does it wrong and I just cannot find out why. Is this a bug or is there a problem in my setup? Thank you!

A) Try reparametrizing the source output via right click (if the output is Curve type).
B) If the curve is a polycurve, rebuild it to have a single continuous curve. I have encountered a lot of strange behaviour with polycurves.

1 Like

Thank you Daniel! Unfortunately, reparametrizing does not help and the curve is a planar singular curve, not a polycurve.
Even if use fit curve or a rebuilt curve, this can happen. I just can’t figure it out.

Upload the curve profile in a .gh file, I’ll take a look.

Here you go, thank you for your time.
While preparing this file for you, I found that it might be due to the closest point having a minutely higher X value than 0.
A solution might to extract the control points of the profile and then do closest point to the controlpoints instead of curve closest point. I will try that.
railseam (9.0 KB)

Man… that worked. Wow sometimes there really is some voodoo going on!

Cool. Replace the Control Points component with a Curve Proximity component and use the gauge rail as the second curve. This way you ensure any profile will have its seam at the ring rail.

well you wouldn’t believe it but when using the curve proximity component it will also happen that curve closest point + curve seam will put the curve seam at a different location. Mind boggling.

Eii @stevebaer, @DavidRutten, to me this is a bug in RH7 SR 7.7.21151.13001. In this curve the Seam fails when t <= 1e-8.
My document is in millimeters with abs tol = 0.001.

railseam (10.3 KB)

1 Like