Hi, I want to know if I should try my character model in SubD's or in NURBS. I will have to apply a bump map, and make the skin transparent (it's a fetus). then, i want to animate it with a few small movements.
Overall, i keep hearing that NURBS are hard to animate. But no one has said exactly why. And i keep hearing that sub-d's are better for character modelling... But again, why? are they easier to work with in the modeling stage? Or are people again referring to the animation?
Finally, if NURBS are indeed better for what I'm doing (it doesn't have to be a processor-saver--it can be "heavy"), should i try to build the whole character from curves made in the front (x) and side (z) views? and if so, what happens when i want to tuck under in (y)? should i add a bottom view?
the tutorials in this forum don't seem to address these questions, or they are too specific to a certain technique.
I don't know where you got this idea that NURBS are any harder to animate than anything else.. in fact that is not true.
The main difficulty with modelling with nurbs is maintaining tangency between patches. SUB-D models can be as complex as you need and a single mesh so no worries about tangency. Nurbs have built in UV's whereas with POLYs and SUB-D's you have to work the UV's.
The problem with modelling directly with Sub-D's is that the sub-d tools are still not as good as the nurb or poly toolset. Fortunately you can use both nurbs and poly techniques to produce a sub-d mesh.
The advatnage of using a sub-d mesh is that you can control the resoltuion of it and you need not woory about patches cracking during deforamtion. The problems with cracks in mulitpatch nurbs models can easlity be solved with a lattice driven deformation or a global stitch however most people do not know abou this especailly when starting out.
Sub-D's are slow to work with slower to animate, Nurbs are fast to aniamte with but the complexity or working with multipatches is tedious and also time consuming. Polys can also be fast to anaimte with but on their own do not provide a smooth resolution.
Working with curves and logft are a great way to quickly shape and object. Then you can covert it another format to take advantage of those features. In Maya 4.5 you can go back and forth pretty quickly and seamlessly between Nurbs, Poly and Sub-ds and then back to nurbs.
The new process that seems to be evolving is to rough out the model with nurbs, then covnert it to sub-d's to make it seamless, then convert it to the mulitple resolutions that you may need for proxies etc by converting to polys and then do your texture mapping and rigging. Or after you have smoothed it out and you convert it back to nurbs and do your texturing and rigging and use a low resolution poly model for a proxy. You can of course control the density of a nurbs mesh more easliy than polys without creating seperate proxies models and have better playback performance.
I have always found that NURBS skills, while valuable, (they can land you a job at Keiser-Walcak), they are hard to attain due to the trickyness of patch modelling and subsequent texturing problem. However, NURBS v subdiv is a subjective problem. It's possible to do the job with both. I personally favour subdivs for the following reasons: 1) You can use the fantastic polygon modelling tools and only convert to SDs at the final stage. 2) uv-mapping is so much simpler than texturing NURBS patch junctions 3) The CPS tools (downloadable from this site) are a fantastic way to model using simple polygon shapes, while simultaneously getting feedback from a highpoly model, which is in essence subdivision emulation. 4) Learning poly-modelling skills leads to sound employment skills. Most games companies want the poly-experience and NURBS is a rare thing in game development. OK, NURBS is probably a good thing to know well for film and TV work, but if you know poly-modelling, then you have subdivs at the touch of a button
I would love to be able to build seamless NURBS characters and be able to sort out all the mapping and skeletal setup, but I find the poly workflow to be much faster. uv-mapping makes things very easy to texture too! As Maya 4.5 has the ability to convert back from subdivs to NURBS (one can already go from NURBS/polys to SD) it will soon be academic which geometry type one picks, as they will be interchangeable. Listen to the opinions of the NURBS fans who argue against my points though, because there is more than one way to skin a cat in Maya! andy d
I've found that texturing on NURBS seems to work better...
Don't alot of game companies use patches anyways? It doesn't seem like polygons are the future, because it would be really slow to have an in game subD algorithm, where smooth patches can be much faster because a surface can be descibed as an efficient algorithm.
Allso having a hires model with good uves allows you to collapse the detail into displacement and or normal maps for even more convincing look at low polycount.
But if the subd algorithm got implemented in the chip itself then its another ballgame (altough we want the quad implemantation not the tri one):
but nurbs do have a much better toolset to work on. Additionaly almost all eingeneering stuff that has ben produced in 3d is nurbs based...
I've only worked at two games companies, so I can't speak for all of them. I've never witnessed NURBS patches being used in a game (although I once saw a demonstration of NURBS on the PS2 at a conference). True about subdiv, now that would be a waste of the CPU's resources, but polygons are still king in games (at least that's what I've heard). So NURBS texturing is easy to setup? Cool, how does one go about texturing a multipatch head, (without DeepPaint, just plain old Photoshop)? Could you point me to a decent tutorial, cause I've always been a NURBS fan, but texturing has snared me everytime.