View Full Version : Why Nurbs ?

05 May 2004, 05:32 PM
OK- just what can you do with nurbs, that you can't do with polyspline SDS ?

I mean, sell us on just what is so fantastic about Nurbs- I personaly am very curious to know just what makes this old technology still attractive to many user's. I kind of thought that Nurbs came about because they allowed smaller processor like machines to move around the wires as in apposed to having to deal with moving around heavy geom, but now, with the advent of modern technology, just why is Nurbs still popular for some?

Is it because there was so much money initialy invested by companies, that they are still attempting to sqeaze out the last dollar's worth with the tools they invested in, while not having to retrain employee's ? Or do Nurbs really have an edge over other methods for specific areas, and if so, please be specific


05 May 2004, 06:01 PM
Firstly nurbs are old in the respect that thay have been outdated, infact I nurbs are going to be around and are going to be used for many years to come. I dont belive they will be that popular here on cgtalk because modeling in Nurbs is a very technical process

I belive that the main perpose for the creation of nurbs was to very accurately model man made shapes. Almost every man made product (car, plane, modile phone etc) is modeled using nurbs before it gos into production.

To be fair its more of an engineering tool than anything else, like I said its mostly used by product designers and engineers.

Aliaswavefronts Studio Tools is the biggest most expensive Nurbs app out there (I think its much more expensive than maya)

heres a an example of off of the best modeling/rendering iv seen,

if you would like to know more got and have a look there, you will mostly see technical man made object. Also have a look at the tutorials page, theres alot of cool syuff there :)


05 May 2004, 06:37 PM
NURBS are for highly accurate models.. not just a bunch of surfaces faked through jagged polylines.

NURBS rules the modeling world outside of animation, gaming, advertising, etc... Its used in product design, reverse engineering, military simulations and analysis, etc...

Whenever you need a model with purpose not just a pretty picture NURBS is the way to go.

05 May 2004, 01:01 AM
Well for design work polygons are just as painful as nurbs are for character work. Trust me I know, I am in the middle of converting the workflow at my job from poly's to nurbs. When your models have to meet engineering and manufacturing standards polygons work more against you than for you. For instance our models have to meet several client specified measurements (up to 150 or so), now with polygons the accuracy of your measurement is going to be determined entirely by how many polygons you have to measure across, the more polygons the more accurate. Now to get a measurement that is accurate enough within tolerance of our milling machines I have to subdivide the surface to an unworkable resolution. So after I take the measurement on the highly subdivided surface, I remove the subdivision and make alterations to the base cage, then re-subdivide and re-measure. It sucks. Often times I have to go back and forth half a dozen times just to meet one measurement.

Now with nurbs it's a much different story. With nurbs I can work on the final resolution mesh with no problem, I can have my measurements as curves on surface so I can model and watch my measurements update in realtime without ever having to retake them. It's a true what you see is what you get workflow.

There are more advantages to nurbs, but's late, I'm off work and I want to enjoy my beer :beer:

05 May 2004, 03:15 PM
Hey, thanks for your reply's guys- hmmm, I will have to keep these things in mind and do some more research for sure.


05 May 2004, 08:50 AM
NURBS is road of the Kings because it come from Boeing,and growing in Alias!
A nobleman's free-from surface. :beer:

05 May 2004, 11:21 PM
"Aliaswavefronts Studio Tools is the biggest most expensive Nurbs app out there (I think its much more expensive than maya)"

there are a couple apps that might be more costly like Unigraphics and maybe Catia. also, Alias has different flavors of Studio: StudioTools, Alias Studio, Alias Autostudio. maybe one other. StudioTools is the low-end at around $3500. Studio costs more; i'd guess $7500. Autostudio last i heard was well into the $10,000+ range (closer to $20k); used it once at a jobsite but didn't use/see the tools that bumped the price so high.

Maya 4 Complete compared well to older versions of Alias Studio (v. 7 and 8) but without the higher-degree curves/surfaces and exporting options (for manufacturing purposes). i think Complete is still limited to 3-degree NURBs. Unlimited has 5- and 7-degree and compares better to older versions of Studio but still lacks a few surface creation tools. what's great is that it now has .iges export, which is great for taking it into CAD and making "solid" parts. but rule of thumb....only take 3-degree surfaces into CAD; so the extra flexibility is often lost. so Complete's 3-degree NURBs aren't a huge disadvantage.

newer versions of all the Alias Studio products have some manufacturing-friendly tools, but it's not uncommon for people to use Alias NURBs geometry for reference surfaces only, and then rebuild it all in a high-end, solids modeling CAD package - mainly so that manufacturing can make changes in the event there is a problem down the road (otherwise it can get kicked way back up the development chain).

06 June 2004, 04:55 PM
first of all.. i don't use NURBS and it's not likely i will in near future... i deal mostly with characters so i don't really need them.. but one advantage of NURBS i know is when you render with renderman which can render pure NURBS surface (not convert it to polygons (internally) and then render it like most of renders do)... this brings enormous speed and memory savings (especially when rendering in film resolution)... sounds great.. but it seems to me that that kind of workflow is affordable only to large studios...

06 June 2004, 06:20 PM
i didn't know Renderman didn't convert to tri's. really? interesting to know... but if Maya kicks out a .rib file to Renderman with NURBs geometry intact, and free renderers like BMRT emulate Renderman and use .rib, than aren't those options for rendering available to everyone?

06 June 2004, 10:47 PM
i didn't know Renderman didn't convert to tri's. really? interesting to know...

i didn't know it either... but guy from ILM who worked on major titles told me that... so i decided to trust him on that piece of information... :) but i can imagine that things in film res have to be really smooth... and with large amount of objects.. this is major advantage of NURBS then... they use alias studio for modeling...

and actually... i don't know if mental ray and BRMT do the same thing... i tried to find out.. no success (didn't put much effort though .. :p ) but regardless... we're speaking of nurbs advantage over polys... ;)

06 June 2004, 11:30 PM
there's an older thread somewhere (Modeling forum?) discussing the advantages of NURBs over polys/subDs for film work. seemed the biggest reason cited wasn't in "smooth" surfaces but in texture size and flexibility. i was curious since i find patch modeling tedious and was wondering why it's still used. might want to look that thread up... interesting read.

i mentioned BMRT because it is specifically a Renderman emulator. and it's free. in which case the workflow advantage shouldn't just be limited to big studios.

any BMRT users out there who can confirm this?

06 June 2004, 08:33 AM

One question here from Rhino users, I have heard that the Rhino v3 interface has changed. Now I am on the verge of getting v3 but I have not seen the previous versions. So can I still use the old tutorials? for someone who hasn't used the older versions? Has the new version improved much and is there any site for v3 tutorials?


07 July 2004, 06:02 AM

Just go to the Rhino site. I have never used previous versions - only Ver 3 - which was just updated with a service release 3c. There are 2 training manuals available from their site - Intermediate and advanced - about 500 pages combined in PDF format as well as the files to support the manuals. There are various short Flash tutorials there also - usually on a single command. They are excellent about listening to users and correcting bugs reported. I think IGES export is also supported in the latest service release if that is an issue for you - someone had mentioned it above in relation to Alias I believe. They have a training CD for sale - $50 I think and there are several 3rd party training CD's also. There are a few tutorials on the web - Several at Renderosity and RuntimeDNA - mostly for support for Poser developers (which, by the way, is obviously NOT manufactring related - though I think the majority of their clients may be manufacturing). I was on their site last night and I believe that I saw that there was training - perhaps manuals for version 2. They have a demo to download if you have not yet.
Not sure if this answer your questions but hope it helps. I was shocked at the prices of Alias compared to Rhinoceros! Rhino is MUCH less expensive!!! I'm mainly interested in two things - creating historical items and texturing. The historical things should have exact measurements so Rhino is great for that as the command line is there for you to enter exact measurements (angle, distance, etc. if you need to). There is also a free program out there called Rhinoman which is related to Renderman - I know nothing about Renderman - just that this exists. All these resources are listed on the Rhino site. Oh, they also offer in-person training all around the world - about $700-$800 for three or four day sessions if I remember correctly unless you are a teacher in which case it's free at some locations. I mainly use Cinema 4D or LightWave and there is a command to turn your Rhino objects into meshes from NURBS within Rhino. - so that I can import them for texturing, tweaking, or animation in the "artistic" programs.


07 July 2004, 07:07 PM
Does studio tools have a "convert to mesh" function? I've been scraping around their site and can't seem to figure out if it does or not.

I enjoy modelling planes and the like and i'm personally growing tired of trying to do them in polys and fighting all the little work arounds that have to be done and am strongly considering going to rhino or some other such modeller.

08 August 2004, 07:14 AM
Thanks JJ54 for your thorough reply,

btw, I think I saw somewhere that the version 4 of Rhino is coming, is that right?

08 August 2004, 07:46 PM
Yes I think Rhino 4 is on the way - I believe they are showing some new features for ver 4 at Sigraph. Explore their site - they usually have lots of info - tht's good and bad - Sometimes you have to explore a lot and then still miss something.


08 August 2004, 11:59 AM

That's not quite true. PRman converts everything (including polys and nurbs) into patches and later into micropolys. And afaik any renderer renders nurbs pretty fast.

08 August 2004, 12:55 PM

That's not quite true. PRman converts everything (including polys and nurbs) into patches and later into micropolys. And afaik any renderer renders nurbs pretty fast.
quite possibly this is correct... as i've mentioned: i wasn't speaking from my personal experience... just listened to what the guy has said... he seemed like a respectable resource, but... who knows... :) i'm bit confused now...

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