ZBrushCentral

Mouthbags

ZBrush Artworks
#1

Modelers often create “mouthbags” and “eyebags” as part of their models. The mouthbag is basically just an inner-mouth-shaped sack that holds the teeth, gums, and tongue so that when your character needs to open their mouth, you don’t see a void in their mouth. The eyebags house the eye balls.

I’ve been told that some renderers, like Renderman, need models to be watertight. This would be another reason for mouthbags and eyebags. I’ve never used Renderman, so I can’t confirm this. Regardless, it seems like a good practice to get in to.

So what’s the typical method for creating mouthbags?

I always sculpt my characters with their mouths closed and, from what I see on these forums, you guys do to. So when you get to the stage where you need to add a mouthbag to your sculpt, how do you handle that?

Do you create a morph target of the head, then use transmorph and other tools to make a “mouth-open” state for the model? That’s about the only way that comes to mind.

Thanks,
Dustin

#2

I’m still new to zbrush, and don’t know about the mouthbag, but I did cover a lesson in which I used layers and the “layer intensity” slider to open and close the mouth. Allow me to elaborate.

Load a head, mouth closed, as a poly mesh. Center it in your screen, and subdivide to higest desired level. Layers can only be manipulated when they’re at the subdiv level you created them at… hope that made sense.

go to the tools palette, Layers menu and create a new layer.

With this new layer selected, use whatever method you like for opening the mouth on your model. For example, I masked off the part of the lower lip and jaw I wanted to move, inverted the mask and blurred it, and used the move brush to part the lips a bit.

When I was happy with the parted lips, I unmasked the model, and played with the “layer intensity” slider in the layer pallette. It will modulate the “effect” of the current layer over the previous layer. Moving it just a little to the right actually OPENED the lips FURTHER, and moving it to the left closed the mouth. Going too far in either direction drove the jaw to the floor or thru the top of his head.

you’ll have to just try some things, and use the intensity slider to see what I mean. The coolest part of it, is that you can literally open and close the mouth (or whatever body part) as much or as little as you want by moving the slider in .01 increments.

hope that helps at least with

#3

Thanks blkspd3. I’m ultimately looking for a method that allows me to create models I can hand off to a rigger using, say Maya, to set up body and facial rigs. A “production-ready” model, if you will.

The more I think about it, the more it makes sense to create a simple, concave area for the mouth and eyes at a very early (and low poly) stage in the modeling process. That way, when you ultimately export your basecage out of ZBrush as an OBJ and import it into another package, you actually have some geometry to support the inner mouth.

I’d love to hear some more ideas from people regarding this.

-Dustin