I always thought about the two technologies this way: Subd: good for quick concepts, visualisations, organic shapes are easy. Downsides: getting clean topology with radii, intersections/cuts are a pain and can become a surgery. Basicly exactly what NURBS is good at. NURBS: great for precision, ma…

Fusion is just doing “to NURBS” in the background of the history tree. The whole point of SubD was an attempt to replace NURBS, it failed precisely because they can’t be trimmed.

Silly me, of course its toNurbs also… Why does it handle radii on toNurbs parts soo well though? [Bildschirmfoto 2026-02-25 um 01.15.37] [Bildschirmfoto 2026-02-25 um 01.08.53]

Rhino 9 WIP has Knife, a new SubD command for inserting points into SubD models. [image] Rhino WIP Feature: Knife Serengeti (Rhino WIP) In the Rhino WIP , we’ve added the Knife command to cut through SubD and Mesh objects. What is this Feature? Knife is a…

[image] Eg1: Why does it handle radii on toNurbs parts soo well though? Not sure what you mean by “it” - Fusion?

I mean booleans and fillets are all “Solid modeling” does, they need to work well or it’s unusable.

Two SubD surfaces, after toNurbs and Trim with each other, respond to FilletSrf as expected. [Untitled-4]

@eg1 Also note that in the current Rhino WIP, FilletSrf has been significantly improved and will give you a filleting experience much closer to what you see in other packages, thanks to the Join and Continue across faces options [image]

One other note: when performing booleans, split or trim on a SubD, the SubD gets converted to a Nurbs object without face packing. As you can see in the screenshot I made, there are more faces than necessary because of this. Currently it is better to first convert your SubD to Nurbs. You can then k…

Why no Booleans for Subd?

Rhino SubD

davidcockey (David Cockey) February 28, 2026, 6:46pm 4

Rhino 9 WIP has Knife, a new SubD command for inserting points into SubD models.

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Why no Booleans for Subd?

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