NURBS - and the point is?

Support Modeling
#1

I’m wanting to have a look into NURBS as it’s an area I have tended to avoid in my modeling. I’m wondering though what the main reasons for NURBS are. Are they an early attempt at making nice curves from the “Money for Nothing” era? Given the smoothing options now available in 3D applications, have NURBS been made redundant?

A few of the tutorials I have seen appear to use NURBS as a starting shape which gets converted to poly for the “real” detail. Or, they are fairly crudely used for one tiny piece of a set, like a kitchen sink. On the other hand, I remember Kyall Thompson (tutor at Media Design School when I was there) showing the class an awesome model cow which turned out to be something of a patchwork quilt of NURBS squares. (He said a student made the model in a single night, or was it a week? To this day I’m not sure whether to believe him)

NURBS feel to me like modeling with magnets compared to the direct vertex control I am used to.

Why do they exist?

#2

agreed the tools in 2.49 are rotten !

but wait till you get tne New Nurbs tools in 2.5

then it will become something a lot better to use and more flexible!

Nurbs comes from old CAD system which where introduced in the 50 and 60’s
i mean 50’s there was no PC or computer for general public i mean! LOL

eveything is modeled with math here and control points allow to better control 3D shape then with subsurf on mesh at least with more precision

have fun with Nurbs

happy 2.5

#3

good gosh, where do you young’uns get your history!? You’re about two decades (or more) off.

50s computer tech was all analog, and there was no imaging technology to speak of. I mean, practical TV was barely ten years old at that time! Transistors were new-fangled and ICs didn’t yet exist. No way they had any kind of visual monitoring or even a human-friendly interface – punch cards and mag tape. How do I know this? I was there, Bucky :smiley:

The 60s saw some improvements. Transistors got smaller and faster and used less power and the first ICs started to appear as the first digital switch tech (basically the same bipolar tech in much use even today) became commercially feasible.

But CAD didn’t start showing up until a lot later still, in the seventies, and then only in very specialized situations, and often done with vector displays rather than the raster displays we use now.

The math describing NURBS was a product of the 50s, but its incorporation into computer-based engineering (CAD, CAM, etc) had to wait a few decades.

#4

yes i remember a thing or 2 about computer history

i was not talking about the program as such but more about the math algo for it
and in mid 60 or end of 60 you had the IBM 360 if i remember well
this is not PC yet which happen only at the beginning of 1982
(the apple came out first )

in 1960 it waspuching card and Mag tape but
the math side was developp in France i think like bezier and Nurbs math tool

so the math was there well before the PC and other big Computer

but your right CAD/ CAM took around 2 decade after that to incorporate theses mat algo in programs

i’m certain most people on this forum don’t know about this
PC history is fun
did you see the PBS special on PC history
very well made and shows how chaotic and crazy it was !LOL

Thanks & happy 2.4

#5

And ironic as hell! While I know I’m not hip on all the details, it always struck me as funny in an odd way that both Gates & Jobs visited PARC at about the same time, and one decided against using much of the best innovation, one adopted & adapted it, while Xerox basically ignored it!

So it goes.

#6

and don’t forget Zerox research teams sold their soft to Bill i think
and he was the one to get all the money much later mind you
but from another point of view Bill built the first DOS for IBM and sold it for peanuts!
so he loss a lot of money on that one!

it’s quit ironic how things happen
but this is how the market reacts i guess
now one can really guess or predict what’s it’s gone be !

but today we can enjoy in our reality all the power of modern PC and soft
at a very low price and even some soft like blender which are free
what else can you ask for !

happy 2.5

#7

but to get back to the main point about Nurbs - why would you choose to create a model in Nurbs as opposed to mesh and subsurf? Is it just style, or are there real advantages? is it just two ways to get to the same place? my understanding is the the Shrek movies use Nurbs for their main characters, while Pixar of course would be mesh and subsurf (a la mr catmull)

btw - I worked on a 3D animation system in the 80s called Digital Arts - it was very sophisticated at the time - and built a cow model - out of nurbs! really. at the time that was the way to do it. but I dropped out of 3D in the 90s and am just getting back into it, so this is all very interesting to me.

#8

reply to myself here: for interesting reading about this, go here

#9

It depends on your needs, skills & uses. It’s like asking if you should sculpt or polygon model to make something.

I’ve done many models via nothing but nurbs. Why? Because I can get a shape a HECK of a lot faster vs polygon editing. nurbs is closer to drawing while polygon is closer to building. I’ve done clothing, animals & cartoon characters via nurbs. I started with polygon modeling but it was taking longer then I wanted to get the basic shape, nurbs sped that up exceedingly.

But when rendering it’s still polygons anyway. :slight_smile: Plus, to say the “math” was in the 30’s, 40’s or 50’s it like saying it nurbs were around ~4000 years ago because they started figuring out trig. And a trig formula can also make a nurbs curve. :smiley:

Interestingly, GPU hardware for game supported a feature like this in 2001 but wasn’t really supported by companies & was dropped a few years ago to be replaced by a DX 10 standard.

#10

don’t forget Zerox research teams sold their soft to Bill i think

PARC was/is Xerox. http://www.parc.com/about/
The Palo Alto Research Center is where Xerox does R&D on new copier technology… unfortunately, Xerox upper management back then were a bunch copier-heads and never saw the potential value of networked desktops or GUI’s w/ pointing devices. :rolleyes:

NURBS are used extensively in product design and CNC machining as the data is resolution independent. NURBS are awesome for hard-surface modeling. See http://www.rhino3d.com/ or http://moi3d.com/

Interestingly, GPU hardware for game supported a feature like this in 2001 but wasn’t really supported by companies & was dropped a few years ago to be replaced by a DX 10 standard.

Are you referring to npatch quadratic interpolated surfaces? (introduced in DX8, marked for deprecation in DX9 , and adios’d in DX10.) Also known as “Trueform” tech on ATI cards…

There’s a reason for that… if you ever tried to use 'em… you’d know they are a real bitch to deal with, especially if you had to support both DX (native via DX8) and OGL (via extensions), and NVidia cards. (Trueform was ATI only). And they never worked very well as it was difficult to get the npatch derived surfaces to blend smoothly with normal poly-based surfaces (for world geometry in games). Also, if you used normal maps, the meshes would tear apart at the UV seams.

http://www.gamasutra.com/view/feature/2980/bzier_triangles_and_npatches.php

At least that’s what I remember the programmers I was working with at the time telling me when I started screamin’ for curved surface support in the game engine we were developing a the time 'cause I read somewhere that DX8 supported them. :slight_smile: (One of which, BTW, went to work on the DX team for Microsoft prior to the release of DX9.)

#11

NURBS is basically applied mathematics rather than fundamental theory (like trig). It was in the 50s when Mr. Bezier and others started developing NURBS formulas specifically to describe smooth curves mathematically in a way that is (as mentioned) wholly scalable & reproducible but also easily applied to practical engineering problems, even before CAD and CAM were feasible. It was also about the time the term was first coined.

#12

also The word spline was first used in a paper in 1946 as indicated somewhere in Wikipedia

And Work on Bezier was pionner by 3 guys one in France working for Peugot i think another one in USA at GM motor and Another one …

Also Nurbs happen around end of 60’s

so all theses Algo where used at first for the Auto indutries
but then it became used all over because theses were stable algos and relatively easy to use and give repeatble precise results.

today we are enjoying all theses Algos in Blender and will see more with the New Nurbs tools which will introduce the New Nurbs with holes in them very soon hopefully
which will boost blender power for Nurbs quit a lot and i can’t wait to test theses new Nurbs tools.
right now Dev are working on the 3 rd new Tool which is the Loft tool for Nurbs
so i hope we can see a built for this soon to test this

happy 2.5 with Nurbs

Sorry for ny English i can give it to you in French if you understand it!

#13

Thanks for the informative info all. Loft tools… that might just answer some of my next question…

If I make a simple NURBS shark, and I want to put in the side fins, how should I go about it?


  • Insert extra side edgeloops so I can pull the side fins out like I did the main top fin? (risks causing crease along the body)
  • Have them as separate shapes and use various methods to mask the seam where they meet?

Seems like choosing the lesser of two evils, but what is the accepted bast-practise?

Also - I have notced some really good Nurbs models out there (Maya) are actually formed by squares of NURBS kind of like a patchwork quilt. Somehow they stitch the edges together so they can bump up the resolution of just the area where they might need more detail (e.g. the eye).

Can we do this with Blender NURBS?

#14

right now you ready to male copy then convert to mesh
so here you needt o experiment and decide woith deresil value to get a nice mesh mode

thne you could make it lower and apply a subsurf and add hole where needed then keep going like a normal mesh

the Loft tool for 2.5 is not yet ready and not certain when it’s coming out !

good luck

Nurbs are amazing tool in the sense that it always make quad face and you keep geometric continuity for the curves so hope to see the New Nurbs tools in 2.5 soon

good luck

#15

Nurbs are to poly meshes as vector fonts are to bit-mapped fonts. No worries about resolution. Since they also control second and higher-order curvatures, one can make very organic shapes very easy. The auto industry thrived on them for body sheet metal as soon as they had the tools to use them. Current mechanical design packages like Solidworks don’t even bother with poly meshes.

#16

Interesting Discussion on NURBS in Blender