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Answered: Why are lower subdivision levels important?

ZBrush Usage Questions
#1

I am really new to 3D modeling, and my apologies if this is one of those “duh” questions. But, I feel the need to ask it because it seems like it’s one of those fundamental concepts that I am just not grasping yet…and I want to get it taken care of before I move further along.

I watch all of these different tutorials on how to model certain objects, faces, weapons, etc. and I see in all of them that the person sculpting is keeping a very close eye on their lower subdivision levels; there seems to be some huge importance to them, but it doesn’t ever get clarified why that is.

So, my question is, why are the lower subdivision levels so important? Especially when they look so terrible (pixelated, no detail, etc)? I understand that certain projects may require a lower poly count, but, if that’s the case, why would a person even bother sculpting in such high detail on the higher subdivision levels when it’s just going to be reverted back down to a lower level?

Let me know if I need to clarify my question further.

Thanks in advance for any help! This is really bothering me that I can’t figure this out, because I feel like once I have this concept understood, I can then move on to the good stuff :slight_smile:

#2

The most obvious reason why thy’re essential is if you’re creating displacement or normal maps so that you can get your detailed work into another program for animation or whatever. These maps are always calculated from the difference between the current subdivision level and the highest one, meaning that they can’t be created if there aren’t multiple levels.

There’s more to it, though.

Any experienced modeler will tell you that low levels are really good for working on the model’s broad shapes and that you should only divide the model when you’ve pushed things as far as possible with the level that you currently have. A common mistake for new users is to divide away and just start sculpting. The result is always lumpy meshes, muddled forms, etc.

But what if you have started fine detailing, but decide that you want to adjust the overall form? (Or your director tells you that you need to for any of a million reasons.) For example, maybe you need to make your dragon’s jaw longer. You don’t want to lose all that detailing you’ve done and time spent on your project. Yet the high resolution mesh isn’t good for making broad changes. With ZBrush’s multi-resolution mesh editing feature, this is easy to handle. Simply drop down to whatever subdivision level is best suited for the change you want to make. Make the changes. Then return to the higher level and continue detailing where you left off. When you change levels, ZBrush automatically adjusts to compensate for any changes you’ve made at the previously worked on level.

In short, multiple subdivision levels give you a non-linear workflow. This in turn gives you more freedom and flexibility to experiment with ideas or adapt to changes.

#3

The most obvious reason why thy’re essential is if you’re creating displacement or normal maps so that you can get your detailed work into another program for animation or whatever. These maps are always calculated from the difference between the current subdivision level and the highest one, meaning that they can’t be created if there aren’t multiple levels.

That’s interesting, I didn’t know that. Do you have any good reading material on this process so that I can become more familiar with this step? So, what you’re saying is that even though you may export on the lowest subdivision level, it still retains that detail from the higher subdivision level?

Any experienced modeler will tell you that low levels are really good for working on the model’s broad shapes and that you should only divide the model when you’ve pushed things as far as possible with the level that you currently have. A common mistake for new users is to divide away and just start sculpting. The result is always lumpy meshes, muddled forms, etc.

Cool, that makes a lot of sense.

But what if you have started fine detailing, but decide that you want to adjust the overall form? (Or your director tells you that you need to for any of a million reasons.) For example, maybe you need to make your dragon’s jaw longer. You don’t want to lose all that detailing you’ve done and time spent on your project. Yet the high resolution mesh isn’t good for making broad changes. With ZBrush’s multi-resolution mesh editing feature, this is easy to handle. Simply drop down to whatever subdivision level is best suited for the change you want to make. Make the changes. Then return to the higher level and continue detailing where you left off. When you change levels, ZBrush automatically adjusts to compensate for any changes you’ve made at the previously worked on level.

In short, multiple subdivision levels give you a non-linear workflow. This in turn gives you more freedom and flexibility to experiment with ideas or adapt to changes.

Thanks for the reply aurick. I really appreciate it.

I think that I’m still a little bit in the dark as to what happens with the model’s details when you go to export it, but I think that’s on me. I need to read up on 3D program exporting and whatnot. I need to find some resources that really bring this concept home.

#4

A ZSphere armature allows ‘blocking in’ of the main forms. Adaptive skin from that shape. Don’t go crazy with levels here, they can be divided further. Divide only when you have no points to shift to refine your forms details. HTH.

#5

I definitely get that part of it. What I don’t fully get is why do you even bother dividing at all? Don’t you just waste time doing all that fancy detailing at the higher levels when you just end up sliding it back down to the lower subdivision levels? Isn’t this especially true when you have a set amount of polygons/points to work with?

Aurick brought up a point that I am still researching/processing: that a 3D modeling program needs the lower and the higher subdivision levels to fully generate the model accurately (it basically averages out the lower and the upper levels?). I’m not 100% sure on what this means in real world application, but I am looking into it right now.

#6

In most 3D programmes used for animation and indeed rendering (Max, Maya, Lightwave for example), you will need to have significantly fewer polygons to work with. 100s of thousands perhaps, rather than millions. Also, in games engines, they may just be 10th of thousands. However the detailed sculpting and texturing will be done at very high resolutions. The topoglogy of the lower resolution mesh is very important in animation as it affects how the mesh deforms during movement.

What one would do is export the lower res mesh from Zbrush with a UV. Then, using Zbrush create for example…


  • A displacement map - used in 3D programme to actually displace polygons and ‘project’ the high resolution details onto the lower res mesh
  • Bump/Normal maps - used to give the impression of higher resolution sculpting on lower res mesh (always what games engines use, but also may be used with displacement maps)
  • Texture Maps - colour etc, information for the mesh.

Additionally, most artists will work at the lower level to ‘block’ out a mesh, and increase division levels gradually. this definitely makes it easier to have your mesh smooth and avoid that ‘lumpy’ look.

#7

What I don’t fully get is why do you even bother dividing at all? Don’t you just waste time doing all that fancy detailing at the higher levels when you just end up sliding it back down to the lower subdivision levels?

Nope, all that fancy detail comes back when you slide it back up to a higher subdivision. This way you can make broad changes to the form (such as making a hand bigger, or changing the pose), and not wipe out details from higher subdivision levels.

And I’d like to second what Aurick said about lumpy sculpts; it’s usually always readily apparently in the result when an artist jumped the gun and went straight to trying to sculpt on a dense mesh without spending time working on the lower subdivisions.

#8

Right on. Thanks everyone, you’ve been incredibly helpful!

cheers!