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View Full Version : The Cons of NURBS?


bblanar
10-24-2006, 02:39 PM
I recently got struck by NURBS. They are rocking my world and I play and can see my entire Character being made out of them. I am wondering if I can keep them forever or if I am going to have to output a poly mesh for texturing/rigging. As far as I read, there are some texture limitations as far as (i suspect) UV Projections.

Could anyone give me a little more info or other issues to think about? What are the cons of NURBS?

The char will not be squished and deformed, she'll have knee and elbow/neck joints, but the armor just shifts.

CiaranM
10-24-2006, 10:12 PM
I also have been really enjoying my recent introduction to NURBS. I'm really quite keen on them now that I'm less ignorant. Unfortunately, I've been learning in another package, which I think is more dedicated to NURBS than XSI (never felt the need to touch them here).
For myself the main detraction for NURBS is that although the techniques involved can at times be very sculptural, the fact that you have to compartmentalise the areas of your model. I really don't like not having a big block of polygons that I can chip away at will. It can be a real pain in the arse to spend time going over and over your seams until they blend perfectly (although that could be program specific).
Technically, texturing is an issue. Each NURBS patch has seperate UV coordinates which is a blessing and a pain. No need to spend time laying out a neat UV map and will play great with procedural textures. But, you'll be messing around with trying to blend texture projections between surfaces. Sounds like a real pain to me. I've heard that DeepPaint can read nurbs and will allow you to paint seemlessly across surfaces. I'm not sure if it plays well with XSI's NURBS though.
Which is another issue. There seems to be less in the way of a common file format such as OBJ or FBX for moving your NURBS between apps. And if there is, I'm pretty sure XSI doesn't support it. Of course, no Zbrush for your NURBS!
SubDs are just a bit more flexible than NURBS in terms of texturing, modeling and so I hear, animating (if not rendering?).

Bullit
10-24-2006, 11:16 PM
Nurbs are good if you have most of your ideas well defined before starting up. It also makes a much better topology than polygons for everyday objects. If the object can be defined by a couple of surfaces it is also super fast to model - you have to set up your mind for that way of building objects - . It' a pain to change and modify and XSI isnt one of the best app for Nurbs contrary to SubDs.

And never forget curve quality defines surface quality.

CiaranM
10-25-2006, 02:29 PM
Also,
be weary of falling too deep into NURBS to the neglect of polygon modeling, particularly if you are just starting out. NURBS seem to be comparatively rare outside of a few big movie houses and of course the design world. But, you seem to be interested in character modeling, so remember to know your polygons too!

giant551
10-25-2006, 06:49 PM
Nurbs are a fantastic way of modelling and very quick once you get the hang of it !!! I have come the other way in my 3d. I started off with Rhino using only nurbs for a couple of years so i can definately see the pro's and cons of both poly's and nurbs. Nurbs are fantastic for things like product vis and concept modelling but if your copying from blueprints poly's gets my vote.

The main drawback for me and nurbs is its not as easy to edit your surfaces as it is with poly's you can point pull with nurbs but to be honest with you i never had much luck with that, the thing i like about poly's is the way you can constantly tweek your mesh right up to the point of freezing it for UV mapping.

cheers

Paul

bblanar
10-26-2006, 02:32 PM
Thank you for the responses.

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