Rhino 6 Thickness settings - Solid check box not producing solid, closed mesh?


When using the Thickness Setting in side panel, I’ve noticed that, despite Solid check box being used if you confirm structure with Check command the object is analyzed as what is was originally (ie, polysurface, surface etc.) not a closed mesh, though it can be ‘Meshed’ later with mesh command- so it appears the offset can be turned into a closed mesh (say, from a surface) but just checking the
‘Solid’ box isn’t supposed to automatically convert the offset from a form or polysurface into a closed solid mesh though it seems to say this in the help section.
Am I misunderstanding what the Thickness option is supposed to do or is this a glitch of sorts?

(trying to write some instruction and don’t want to create confusion)


That Thickness feature is just a “render-time” feature, it’s not “doing” anything to the underlying geometry.

Thanks for that…
But it is confusing, because if, after using it you perform a mesh you will get a closed mesh.

For example, if I create a primitive cube, and extract a face then mesh, I get an open mesh.

If i do the same, then use the thickness offset, then mesh that,
I get a closed mesh.

So what I’m I not getting?


Well, I guess just that the render meshes are a totally separate thing from the underlying NURBS geometry? The render mesh is not the model, it’s just this thing that exists in Rhino because video cards can’t yet tesselate NURBS in realtime themselves. All those effects are just intended as “rendering-only” effects, not for “real” geometry–though of course sometimes they are useful for that where you can get away with a mesh.

Would be really nice to know what it is actually doing and how it’s accomplished so to be able to explain to a new Rhino user.

See ‘Solid’…


If you scroll up the title of the page is “Thickness–Render mesh modifier” and it does say what it does. There is a collection of those mesh effects that work all the same. Is it the way it’s explained easiest thing for a new user to understand if they have no 3D experience? I dunno, maybe not, it’s not frankly a feature I would even introduce in beginner training, what people need to seriously learn to use Rhino effectively are how to make clean geometry and the quirks of working with NURBS surfaces, these effects that are just intended as shortcuts for nicer concept renderings is…well something you might talk about if you were able to get around to rendering. Or I might talk about them after introducing what “render meshes” are and how the mesh is not the model.

I completely get it… but you see what I mean,
And nothing worse than students saying… 'but it says ‘closed mesh’ here… and then replaying, well I don’t know

exactly why it does this, but not this, even though it says ‘that’, and they can’t say Exactly why either.

Also because it’s easy to stumble over in the properties panel, where you want people to be routinely keep their

eyes, they will go there sooner rather than later.

It may be true that it’s a modifier, but it is also true that the help says ‘closed mesh’,

which is confusing.

@KelvinC (alerting Help Files monitor-check clarity)

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Thanks for the heads up. I’m reviewing the topic.

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Thanks, these are bugs. I just filed a bug report for the issues.


Thanks for follow up!