The zBrush Analogy


In discussing interpolationless animation techniques, an analogy I keep coming back to is zBrush and other sculpting apps vs subdivision and NURBs modeling. While subdivision surfaces almost completely took over from NURBs as the most common technique for DCC modeling in the early aughts for very good reasons, the two methods of modeling surfaces have a lot in common. They both create a surface out of a relatively small number of control points that the user can manipulate, and it is the job of the modeler to place these control points in the right relationship to create the desired surface.

At first blush this seems like an obvious good. Manipulating a surface from a limited number of points must be easier than dealing with a huge mess of polygons, right?


It turns out that dealing with a whole bunch of dense data is frequently better--as long as you have the right tools to do it. Until zBrush came along, nothing did. But once it had a chance to refine its toolset and retopology became a common technique, the advantages were so tremendous that now zBrush is sometimes used for hard surface mechanical/vehicle modeling and even product design, areas where subdivision or NURBs modeling would have seemed like an obvious choice!

I think this shift suggests some fundamental ideas about the best ways to approach content creation. There is a tendency to assume that “non-destructive” or “procedural” methods will always be the more effective, creative technique, when in reality using them when they are not appropriate can be crippling. For instance, digital painters frequently make use of layers and layer masks, a beneficial non-destructive workflow. But try telling a digital painter they have to make all their art by putting down Bezier control points to describe a brush stroke instead of using a Wacom to lay down pixels. Being infinitely tweakable in theory does not necessarily equal a better workflow in practice.

Any sort of non-destructive editing introduces an element of indirectness to content creation. Instead of editing a thing, you are editing a thing that makes the thing. Sometimes this is desirable. Bezier curves are frequently the right toolset for graphic/logo design because smooth and simple shapes with precisely defined curvature actually benefit from this indirectness. Tasks that require minute fine-tuning like compositing practically demand it.

There is an entirely different class of tasks, including much of painting, sculpting, and, I would argue, character animation technique, where indirectness can be disastrous. But there’s no zBrush for animation, no animation package built around manipulating dense animation data directly. The animation equivalent of subdivs/NURBs is all we have. That’s why the techniques I’m presenting here are currently only viable in certain stylistic contexts. Interpolationless animation is highly effective for the kind of cartoony, highly stylized animation I want to do. But it presents obvious problems if you’re doing more traditional, naturalistic CG!

In a future post, I’ll examine what an “animation z-Brush” might look like.