Flat or what?

Grasshopper
1

I thought I could rely on the “Is Planar” component to parse the flat and non-flat surfaces ; it turns out to be un-reliable.
My Rhino tolerance is 0.01 in mm. If I extract the borders of that surface and try to make a “PlanarSrf”, Rhino justly refuses, as there is a 0.074mm height offset on one corner.
Yet, Grasshopper’s “Is planar” component considers it planar.

250218_IMG_Flat or what
250218_IMG_Flat or what2480×975 410 KB

250218_PROG_Flat or what.gh (8.3 KB)

2

At least, the “Boundary surfaces” component detects the non-planarity.

250218_IMG_Boundary surfaces to the rescue
250218_IMG_Boundary surfaces to the rescue1552×649 72.4 KB

3

Thanks for your report and I have logged it,

isPlanar
isPlanar1656×520 111 KB

4

would be nice, if the IsPlanar Component has a tolerance input - at least as (+) extension.
And the default Tolerance should be documented.

Meanwhile I see 2 workarounds:

  • use a scripting component
  • use plane / boundingbox / z-Dimenstion and compare against a tolerance value