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deleyt
07-26-2010, 09:09 AM
Hello. I've been modeling (mostly boxmodeling) some time now and eager to learn, I frequently study models made by others, as most of you probably do.

My question is this: When I build large flat surfaces I never use subdivisions in order to keep the model as light as possible, however now and then I stumble on models by others with large flat surfaces, like buildingwalls, that use subdivisions. I was wondering if anyone could explain me what the purpose would be of subdividing such a large flat surface?
Thanks for your help in advance.

EDIT: PS: I'm talking about models for rendering, not gamemodels (I.E. using a game renderengine)

korthuran
07-27-2010, 05:46 AM
If you had an example that would make it easier to answer.

I do it out of habit. The extra poly's on a large flat wall are really nothing at all when it comes to render time. A drop in the ocean.

If you build the scene to smooth but don't make everything to smooth when you get ready to render it can be annoying to realize you've accidentally smoothed something not built for it and have to re render.

There's all sorts of reasons for it. Consistency. Habit. Ease of use. Zbrush. The seams between objects look better.

deleyt
07-27-2010, 12:44 PM
Thanks for your reply.

If you had an example that would make it easier to answer.
I've attached an example of Evermotion's ArchInteriors regarding a bathroom interior.
As you can see, the walls, floor and ceiling are all flat surfaces, yet contain many subdivisions.

The seams between objects look better.
That I can understand. Seams, cavities, wrinkles, all need more subdividing to get more control about the angle (sharp or smooth). But looking at the example, would having so much subdivisions be any different to just leaving them out, thus saving renderingtime?

korthuran
07-27-2010, 05:58 PM
From the looks of that wire frame it appears that there are definite reasons for the extra lines as in there is geo that needs those edges. I can't say for sure what they are since I can't see it well enough.

But even if there weren't the extra edges the render times would be all but unaffected by the extra geo. You need a lot of extra geo to start hammering the render times. A scene that small won't have any issue with poly count.

There is another reason though that I forgot to mention before and that's anti-aliasing. The larger/longer a poly face is the more difficult it is for the renderer to properly anti alias the geo. That is one major cause of longer render times. If you have to bump your anti aliasing settings it can kill your render times while adding a few extra edges won't make any difference at all.

It's a balancing act between clean and efficient geo and the render settings.

deleyt
07-27-2010, 08:35 PM
There is another reason though that I forgot to mention before and that's anti-aliasing. The larger/longer a poly face is the more difficult it is for the renderer to properly anti alias the geo. That is one major cause of longer render times. If you have to bump your anti aliasing settings it can kill your render times while adding a few extra edges won't make any difference at all.

That's a very clear explanation! I will definitly use more subdivisions on flat surfaces for my models in the future. Thank you very much for your help, Korthuran!! Much appreciated!! :)

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