Topology in Production, if it doesn't deform, does it matter?

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  05 May 2013
those are nice models.

I'm sure most people here are dealing with models that are similar in nature and quads are the way to go even if it means taking some time to retopo the surface until it's perfect for your needs.

I can only speak for myself, but I'm in a situation with my models where if you started with your character model and then your director started asking for a shot where you needed to slowly go inside the character's mouth and look at his tonsils. You already have your model "done" and it's perfect, but now you need to extend it to have the polys wrap around the inside of the cheek and back to the tonsils. The topology might get messed up somewhere because it originally didn't account for these extra new areas, but you spend the time to make the topology nice and neat anyway.

Now the director says the character's arm needs to get cut off with a laser, but not along an edge loop and not along a straight line, but a very specific zig-zag line where each polygon needs 20 points of resolution inside it where the laser will travel through. This will be an n-gon/triangle nightmare. You can fix the ngons/triangle slivers manually, but it'll take forever and you'll have to add in a lot of sideways edges so the triangles are long and thin.

So you do all of that and then the director says the next shot involves the character dreaming he has 5 arm and each arm has 10 fingers and they don't cleanly come out of any of the existing polygon locations. You'll have to subdivide the locations until you get the root shape's branch point just right. The texture artists are going to have fun dealing with this too.

Now the director says the character gets shot with a couple bullets asks you for the next shot, to cut the model arbitrarily to align itself with the bullet holes - which also have to be physically modeled....while the character is running and in motion. You can't have any weird pinch points or triangle slivers bunching up locally. It all needs to look smooth and clean - because we're going to zoom up close to 1 square cm and spend 30 long seconds staring at it all so everyone will notice if you have any topology that stands out from the neighboring topology

Next you're asked to pull out an arbitrary bulge across the models forearm because he has a tumor shaped that way. You might rely on displacement maps, but the director wants to zoom right up to the tumor to frame it a certain way so you start wondering how you can model it and deal with fixing the potential ngons/triangles it will introduce to the mesh.

Maybe those are easy things for modeling experts to deal with - I'm certainly not one, I'm just a generalist, but seriously, what if you're asked to do each of those things in a few hours?

At some point, you'll have to decide if you really have time to deal with maintaining perfect topology for all these scenarios or if you find a way to not have to deal with topology by throwing it out the window if you know this character is going to have to do all these things before you model, rig, and texture him.

Random unbiased triangles don't care if you have to cut up the polygons in an arbitrary way and potentially give you more position options for adding additional branches because they aren't biased by a topology flow.

Last edited by sentry66 : 05 May 2013 at 09:52 PM.
  05 May 2013
Noone was talking about modeling gods here. Please keep the discussion civil.

Also, I understand that there are some very specific requirements and unique cases where the general approaches will inevitably fail. But the guy who started this thread will probably not meet such cases, so does he really need to be prepared to deal with them?
Tamas Varga
  05 May 2013
sorry, I thought I was being civil.

I changed the word "gods" to "experts" and emphasized that I'm not a modeling specialist.

I know most people aren't going to need to do things like in my last post, but you were asking about what topology issues are people encountering that can't be solved by existing quad tools. You've obviously been able to get good results from quads for your needs, but I wanted to give some examples where quads might have potential issues or at least have for me in similar situations.

It comes down to having flexibility to significantly change the model after it's been "finalized"

Quads have a tendency to need to flow a certain way which can make major arbitrary changes a pain to always conform to that topology flow

Last edited by sentry66 : 05 May 2013 at 09:50 PM.
  05 May 2013
I think most productions handle 'special cases' (bullet hole details, etc) with unique assets built for and within confines of a specific shot/sequence.
The regular character assets are not usually modified directly-(because 97% of the other shots don't require it-and who wants all that messy detail hanging around).

I could see with your medical stuff its quite typical.
But for general VFX (and the like) - only productions that have a sequence that mimics a medical animation is likely to need anything like that
(is it CSI that did stuff like that?!-i can't remember...)
Anyway-and probably shot specific assets would be the order.
  05 May 2013
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