Theoretical SUB-D

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  01 January 2003
Post Theoretical SUB-D Discussion!

Hey, all.

I'm starting this thread as an extension to a thread I started titled "How'd He do that?". That thread fell off topic and I chose(though now to my dismay) to delete it. I didn't realize it was of so much use to the community. So this is the new thread. I won't delete this one. I promise.

I'd like for this thread to be a place to discuss the obscurity, the trickery, rules and cheats of subdivisional modeling.

Let's talk technique. Let's talk theory. Let's get deep.

Why sub-d?

What are the rules?

Which rules can we break?

What, if any, are sub-d's limits?

Where do you start?

Can sub-d modeling create things other than characters?

What's the best way to model X?

What tools do you use?


If anyone is still interested in talking about fausto's amazing polygonal voodoo, you can read about it, as well as see his impressive wireframes here:

http://www.cgtalk.com/showthread.ph...5&pagenumber=12

Thanks for the read, and I hope we can make this a useful and fun thread.

Let's start by seeing what we learned from the last thread. Did everybody understand it? Questions? Comments?

-3DZ

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Last edited by Dave Black : 01 January 2003 at 04:13 AM.
 
  01 January 2003
Just to get in, I was one of the people on the discussion last time, so I'll be helping out here as I can. I have a lot more experience in more technical modeling then organic modelling but hopefully, I can trow in my own bits aswell

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  01 January 2003
Awsome to see you here, Viper!

Your mechanical modeling skills will really come in handy.

Thanks for contributing, man. This is gonna be cool.

-3DZ

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  01 January 2003
Small rant ensues: You deleted it?! Why did you delete it? That was a great thread, with a lot of useful information in it, a good intelligent discussion, and for crying out loud lildragon went to the effort to put up those wire shots of Fausto's Marine-- I just spent 10 minutes hunting around for that thread and pulling out hair over it, please, don't DO that!!! Start a new thread if you want, but for crying out loud don't take things down unless you have to! Let the mods decide which threads need to go! ...Okay... I'm done... still fuming, but done... sorry..

One of the main questions I'd like to see answered is, are Ngons okay or not?? I keep hearing conflicting opinions on that subject... after all, Fausto's gun has a lot of them... but people keep shouting 'all quads! only quads, or there is no saving your soul!', so I'm getting pretty confused.

The next question would be, in organic modeling-- what about those darn tris? Again, Fausto's head has a lot of them. Other advanced modelers seem to use them sometimes too, yet in the background I still here the 'only quads! think of your soul!!' arguments from most people... this needs to be sorted out!
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  01 January 2003
N-Gons. Can you use them? Sure. It's up to you as the modeler to decide when and when not to use them. The idea is that they cause shading errors as meshsmooth makes everything into quads. This removes your control from the final output, as the smoothing function makes a "best guess" at where to swing the quads to make it uniform. This can also have adverse effects on the object as it deforms.

Sometimes, N-gons can give an effect that is prefered. Some joints work well with ngons.

The same is true with tris.

I too get a bit ticked at how people's first reaction to many wireframes, is "I see 3 tris on your model...you're going to hell".

Thing is, most of the time 2 or 3 or 100 tris are not necessarily going to effect the final output. People are pretty much harping on proper THEORY. Sort of like ya gotta know the rules before you can break 'em. It is possible to make a model completly out of quads, but sometimes deadlines and artistic vision get in the way.

That's my opinion on the matter.

As for fausto's character model? The textures rock, but IMHO his mesh is going to bite him in the butt. It, to me, is too messy to be really be proper. Blizzard may look at this as a problem...but probably not.

The other issue with using quads and tris, is application specific. Many game engines don't handle n-gons, and using a tri will result(sometimes) in 1 more poly than needed as it get's bisected on import.

Just some thoughts.

-3DZ

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Last edited by Dave Black : 07 July 2004 at 03:41 PM.
 
  01 January 2003
Well, when I first saw fausto's thread, I like everyone else thought, "gee, thats good".

But when I then read 3DZ's, "How'd He do that?", it really got me thinking, darn you 3DZ

I then did a quick test, with poly modelling to make that round smooth surface with those little rivit holes on the side. Its not as easy as one may think. Though I didn't have as dense a "low-poly" cage as it turns out fausto used, so having now seen the wire frames it will be interesting to give it another go. One problem I found was that at the spot around the rivit, the "smoothed" surface had a bump in it. But again that may have to do with not having a dense enough low-mesh.

Even so, I am starting to think that there is very little that can't be done with sub-d.

Gnarly: to partly answer your question, one reason why fausto gets away with those Ngons, on the gun, is because there is no animation, ie the mesh doesn't deform for things like facial animation.
As for the tris on his head, it can depend on where they are located, ie how much deformation happens at that spot. Also remember we are talking a man in this case, so really smooth skin may not be whats totally wanted.
 
  01 January 2003
Quote: Originally posted by tonygib
one reason why fausto gets away with those Ngons, on the gun, is because there is no animation, ie the mesh doesn't deform for things like facial animation.


Now that you mentioned that, you got me thinking a little bit.

That gun, is a perfect candidate to be modeled with a diferent technic other then Subdivisions. Except maybe for a couple of objects, like the handles, the rest could be substituded by lofts and other crazy modeling technics of teh like....it would generate a more optmized mesh then using Subdivisions...

Gotta think on this more
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  01 January 2003
Your right about that, Viper. At least that's what I feel too. Not trying to pick apart his model, as it's amazing, but it would seem that it flies in the face of good sub-d theory.

Can we actually define Sub-d?

Is it anything made with polys? Really. If you used a poop-load of techniques to make alot of geometry, then welded it all together and meshsmoothed it, would it count as sub-d? I think so. Because the theory behind it holds up. Maybe not. Seeing as that Sub-d really means the method of reaching an end, if not a certain toolset...hmmm..brain hurts.

-3DZ

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  01 January 2003
Not really sure. The last time I used subdvisions was to make a Space Cargo Ship, and after that I started to detail it with Shapemerges and edit mesh.

I don't think subdivision is something that holds at the end
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  01 January 2003
One other thing to consider, is that rigged motion is not the only concern when it comes to N-gons.

Other animation types rely heavily on good mesh topology, such as dynamics and morphing.

I think a simple rule would be:

1. Quads are best

2. Tris come next

3. N-gons are last

That almost rymes.

I think if you create the model with topology in mind, it's easier to get away without using tris or ngons, but really, I think I've made one model in my life that did'nt have any tris or ngons. It's doable, but why?

I think the trick is to model with care, but not allow the whole tris/ngons issue to get in the way of getting the job done. Once the model is made, you can always clean it up. And then you can evaluate whether that triangle around the ear or nose needs to be there.

I don't want to waste my inspiration on getting rid of triangles...

There are pros to using tris and n-gons. The biggest help from them can come from savings in polys and time by not having to re-route an edgeloop, or define a new one.

whew.

-3DZ

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  01 January 2003
I agree with that. When i made my car, there was some places that I just had to use triangles or I would have to come up with something much harder....

BTW, I do model my cars with Subdivisions.
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  01 January 2003
So does that answer your question, Gnarly Cranium?

Quads:
Are prefered whenever possible.

Ngons:
Should be used sparingly, if at all, with the understanding that they should either be hidden, or in a place that does'nt deform much. If being used outside of max, say of a game engine, check with the lead artist or programmer to see what the engine will allow.

Tris:
Use tris if you can tolerate their behavior. Usually, the head is a place where there should be very few, preferrably none.

All in all, no tris or N-gons is the best. Few is a acceptable, but alot is lazy.

Always play with the puzzle by re-routing edgeloops, and reconnecting vertexs. Sometimes you can make a quad look like a tri in order to get it to work.

Of course, one of the funny things, is that with Sub-d we are supposed to be keeping all the polys pretty much square. 4 right angles. Weeee!! Of course that's rediculous, but something to strive for.

-3DZ

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  01 January 2003
Ok, how 'bout a little technique?

I often use my own custom "primitives" when modeling. They are setup with all the proper parameters, and stored in an easily accesible place. I find that if all your primitives are similar, that they well easily flow together along proper muscle and tissue fibers, as well as connect with each other easily. They also force me to keep proper mesh topology from the beginning, as they have some smarts built in...sort of.

I've found the primitive on the left is one of the most useful starting objects. Anywhere where the skin of the body comes to a hole, such as the eyes, mouth, nipples, belly button, etc. would be a great place to use this object. It makes you create an almost perfect deforming mesh everytime, and is pretty easy to use.

Here's an example of what I'm talking about:
Attached Images
File Type: jpg primitives_example.jpg (17.8 KB, 6205 views)
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  01 January 2003
Great topic!

One of the things that struck me when i first got here (cgtalk)
was how many people that were "puritans" in their modeling.
I always saw all the tools as the means to an end, that is whatever gets the job done ill do.

So i never really thought about Sub-dos or Sub-donts until i got here.

Is sub-d anything with meshsmooth on it?
I almost always throw a meshsmooth on top of what im working on. Habit from slower computers, and still works fine for me.
So i guess ive been a happy Sub-dude (i know, i know...) as long as i ve known the meshsmoothmodifier existed.

Quote: Can sub-d modeling create things other than characters?

Im making props for my short with sub-d:s. Thats everything from sofas to waterpumps. Wherever it fits.
But maybe thats not real sub-d:s?

Im a bit unsure on the definition.

edit:
(woah while writing you posted this! Great tip!)
 
  01 January 2003
And here's a progression I did real quick to show what I mean.
Attached Images
File Type: jpg progression.jpg (26.5 KB, 7450 views)
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