QUOTE(SlimGoneFat @ 01/10/06, 03:17 PM)
What are the differences between each? I have read that maybe polygon or Sub-D would be better for animating than NURBS but why exactly? Due to my inexperience im not sure why i would pick NURBS over Polys or Sub-Ds... thats the problem.
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Well its a bit untrue, but its easier to play along with this common truuth than trying to explain this. (99% of poeple can be wrong you now, 1% gain a aslifght advantage down the road)
You cant realy sparate the 3 or atleast you cant if you use maya, because some of the best polytools in maya come in form of nurbs tools.
You wouldp pick polys for following reasons:
1) simplicity, polygons are just simple to work with, even tough theres a lot fo tricks up that alley ist usualy the msot simpla nd straighforward way in and out. Offcourse thismeans ot also offers the best possibble way of selfdelusion.
2) modelling for games
3 modelling something that IS realy facetted.
Now polygons have a problem they are not realy curved at all its just a aillusuion brought to you by very clever use of the computer. This has some mathematical and precicion implications. Usualy tough a polys owrk fine forma range...
Nowthen to carter for this you have a choise between 3 parametric surface types (maya has 2 sets of subivs!!).
What procedural means it that they are interpolates in soem parameter space, a bit liek 2d splines they are smooth in mathematical precicion. While they are convertted to polys when rendering for moist parts they are exactly their shape, wich means you could possibly zoom in proever into them withous seeing facetting. Th methamatical implication is even greater, and thus they work much better with certain things thet use real point in space.
ok nurbs or subdiv?
well a nurbs surface is a 4 sided splinic patch its like ultraflexible paper. But it will allways have 4 sides no matter what, you can cut it offcourse just like paper but its still going to be 4 sided. Now then this mans thet if you want to make a human shape you cannot do it with one nurbs surface... this seems wieerd to people who think in object but it actualy makes a lot of sense in soem situations... while most of you thinkof a mug as one object it is in reality 2 just fused togehher. Now the nurbs approach is pure tach and maths stuff often so most users dont like it because of this.
Subds are similliar to nurbs in that they are procedural, but they havent gotthe 4 sided contraint (or so it seems), because they build patches on the flyn to suit the polycage they are formed off. This means its usualy easier to work with them than nurbs. Ubnfortunately they carry some of the downsides of polys aswell. (this is relative)
Youd choose NURBS if.
1) you do booleans,
2) manufacttured good or need fillets and rounds on arbitrary cyrved objects
3) understand tesselation and rendering.
4) do maths
youd choose subds for the same reasonsa as polys - re3solution constraints.