SubD to Nurbs - clean surface?

I am sorry I was not clear. It is officially called shut lines : https://docs.mcneel.com/rhino/6/help/en-us/properties/shutlining.htm

It might work too modify the object after converting it to NURBS.

Hi Kyle
Thanks for volunteering to sacrifice your hi-preformance computer on the altar of TechSupport.
As my 2013 MBP does not even qualify for minimum hardware requirement.

I’m still finding out and learning the Rhino & Zbrush pipeline
I try to do the jewellery body [main parts] in Rhino as long as that makes sense, and then send to Zbrush for sculpting / ornamentation / engraving. Basically just doing on the computer the sort of work I used to do by hand directly on hand fabricated gold part.

Haven’t used Nano Mesh or HD geometry in ZB yet… so parts can go up to 20 million perhaps for the required resolution.
and yes, it then can be Decimated a lot without losing any details.

So the big wish is if there was a way to bring Quadremsher in Rhino to take the decimated geo, and convert to SubD using the same idea! meaning large faces where possible, and very small [subdivided] faces in the areas of small details.

Here from hi poly


to Decimated geo with dens areas where small details are

unfortunately Zbrush does not maintain quad geo when decimating. But rhino could do it! as subD have no problem with Ngeons so the border between the dens details and the large faces is [in my user logic] possible.

thanks a lot
Akash

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Hi Scott
I tried to experiment with shut lines [first time thanks for opening that door] But I’m not sure how this can be of use in my work… it’s a render mesh thing, so it does not actually being applied to the nurbs part.
For curving in mesh, ZB, is no match really. this is one of the main reasons I work with it together with Rhino.

thanks a lot

Try the extractrendermesh command and you should get the modified mesh.

This is just experimenting with workflow. When are NURBS required and when are meshes required? What is the final fabrication technique?

All this new tech allows us to go back and forth much easier then before. But it also creates a lot of questions about the most efficient workflows.

Apology, my last reply may have not been written well.
I can’t at this time imagine a scenario in my work where I would want to modify mesh in rhino [apart from quadremeshing to subD] I have access to ZB so why would I want to struggle in rhino when it comes to things like ornamental engravings…?
The issue I raised these questions was in regards to arriving at the optimum way of getting the ornamented mesh into rhino Nurbs where possible.

again apology for misunderstanding, I’m not always very good communicating.

Mostly it will be STL for jewellery printing.

Yes, and this makes it very interesting and relevant to my [Still developing] workflow.

work flow sequence [as far as I found out by now]

  1. Making main parts in rhino [nurbs + subD] > then sending a very dens .obj to ZB for ornamentation and other work. > then rendering [Keyshot] and decimating dens mesh to .stl
    [I may open the .stl in rhino just for inspection but won’t modify it in any way.

  2. But often, the ZB mesh will need to go back to rhino for gemstones setting and other precision needs [or simply to add a part that I’m more comfortable making inside rhino].
    At time I can make all these parts separately and leave the ZB mesh unmodified [inside rhino] then take all back to ZB for Live-Boolean and finish the work in there.

  3. Yet, many times it would be [now already possible with simple geometry] very helpful to go back with the mesh to rhino nurbs.
    I tried to imagine a way this can be developed to work for very detailed parts as well. [wrote it as a replay to @theoutside. above in this thread]

thanks a lot
with best regards
Akash

Could the “packed” option be also be implemented for the regular Rebuild command?

(Also, why “packed”, which to me, as a non-native English speaker sounds denser than the original, when it from the outside looks as if it should be “optimized” or as the topic says “clean”?)

I am not sure which conditions must be
satisfied for data conversion to occur correctly.

In my think Sub-D → ToNURBS very NICE.

Test Rabbit is Rhino Forum User up-load file. Thank you~

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I wrote a bit about adding face packing to general Nurbs surfaces there: Packed Faces options in Rhinocommon and/or for regular polysurfaces. If you have examples of workflows where this would be useful to you, I’d really like to have a look at them.

“Packed” here is in the sense of a tightly bound group of faces. When we are packing faces, we are grouping a contiguous rectangle of faces into one big surface. The problem with words like “clean” or “optimized” is that they will mean very different things to different people (i.e. are your criteria for a clean surface the same as mines? what value are we optimizing for?), so using them leads to misunderstandings.

How about ‘merged’?

I’m running an older WIP due to circumstances, but it seems that “packed” sometimes ignores sharp edges:

Hi Robert -

Without an actual file, I’m afraid there’s nothing for us to try and reproduce…
-wim

Hmm… I can’t actually get the same results now… guess why that’s still beta…

Using and commenting on an older cut of the beta is not useful. Please update and test this again. If it’s still a problem let us know, as we need to get it fixed.

@akash
How did you setup symmetry for that bypass ring? How do you setup that symmetry to be kinda like a ‘rotate with a copy’ to the other side?

Hi
Sorry I don’t remember what I did 3 years ago… Are you asking how to do a roteted mirror in Rhino or in ZB?

In Rhino, as you wrote, Rotate with Copy + History. Or ArrayPolar 2,

HTH
Akash

Oh ok. My bad, for some reason I assumed you used SubD to create that cool looking bypass ring. Maybe you just used good ole sweeps and surfaces. :slight_smile: Have a great day and thanks for the reply!!

It probably wasn’t yet available at that time, but if you need in SubD, you can now use the Reflect Polar with 2
image

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Hi! I also wanted to bump up this extraordinary vertex problem here Extraordinary vertices problem, as it might be related

Not sure if this is a math issue (e.g. impossible to achieve due to math), but besides continuity problem, there is also deformation (a dent) where six patches meet. The base subd mesh came from quad remesh.

Also, I want to say that Rhino’s subd-to-nurbs is super awesome! It’s like so fundamental to NURBS-ing many great designs.

From what I remember, developers decided to have “not too many” control points in the output nurbs surfaces to have a simpler and faster math. I can be wrong.
This means that at the extraordinary vertex there is some imperfections.
Rhino 8 have G1xx continuity that does quite a better job than G1x and G2…


I agree. Working with SubD in Rhino is extremely quick, smooth, snappy fast! Awesome indeed!

I remember T-Splines being much slower and the output was not always reliable (same geometry , sometime different nurbs output… ).
T-Splines did a better job at extraordinary vertices, but the control point count was higher.


Try Rhino 8 G1xx

and/or

Try make your “flow” of quad faces better where you need complex double-curvature details, push non-quad faces and extraordinary vertices where your shape is less curved, to flat areas.


Current situation about SubD output is not bad at all.
We just need more controls over packing, control points manipulation, topology, analysis… both manual and via scripting…

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Thanks for your detailed advice Riccardo! G1xx sounds very helpful–I will explore it more next time I use Rhino and GH!

Places where >=5 surfaces meet have been a headache (subd to nurbs, RhinoCommons in GH), but I (think?) it’s looking better since R8 (could be hallucinating). From Alias (and sometimes Rhino) videos, it seems clear to me that good curvature continuity (no obvious breaks or turns in Zebra line) over such areas on a model is indeed possible. I’m hoping it could be done without ‘control point massaging’ or Xnurbs or (very useful but crazy) surfacing techniques