Modeling a foot in Maya

I won't explain every detail in the beginning, you can get to the state in the next image several different ways. For example like this: polygonal box modeling. (This isn't meant to be a step-by-step cloning; it's more of a general workflow thing.)

This is the model I started with for this session - a simple model several years old that I'd previously used as the 0-level of a hierarchical SubD surface. But I wanted to rebuild it without the hierarchy (mainly because I plan to render it in Renderman one day). [Below]

Say we're going for realism. Well in that case this isn't working. It needs more detail, and for that we need reference. Also, the topology is bad. (I could make it better without reference, but I knew I'd need it before the end so I made it the first order of business.)

The best reference is without a doubt the actual human body, and I did use my own foot to some extent, but good photographs do have certain advantages over the living body (like for instance, my foot is really ugly). I used reference images from Peter Levius great site - I found about 4 different women's feet there, from several angles, quite close up, flat on the floor, which was exactly what I needed. (I can't show all of them, for copyright reasons.)

To those who doubt the usefulness of a traditional art education to a 3d modeler, I hope the following may help to sway your opinion a little. First I sketched the major shapes I could see, then I sketched a preliminary topology. There's also a cross-section showing the spacing of vertical edges around the back of the ankle.

From here I started adding and deleting edges to the old model. On the left, the red lines indicate edges being added, and on the right, the highlighted edges (orange) are about to be deleted.

A view showing some points being pulled to the left, as seen on the right.

More edge-insertions and deletion steps below

At this stage I felt dissatisfied with the SubD version of the foot - it was still too smooth, and lacked detail.

One of the most obvious characteristics of the foot is it has much more detail than many other parts of the body. The contrast is especially apparent on women. It's also true of course for hands, knees, elbows and central/lower front of throat etc, though usually less so.

So I went back to the reference and did another round of sketches. On the left I've highlighted 'knobs' of bone and muscle that are visible most of the time, on most feet. On the right I've underlined the drooping shape of the ankle bone. Another thing I noted, which was unexpected, is that on some women the first knuckle of the index-toe - it's 'base' - is lower than that of the little toe.

With those knobs added:

And the final topology:

Select these edges, then do a Subdiv Surface > Full Crease.

A lot of people seem to think that polygons with 3 or 5 sides are bad when converted into SubD's, especially in other packages but also in Maya. I've never seen any other valid reason given (for Maya) than that it makes the file slower and heavier, and creates bumps where you might want smoothness. (Oh, and that MR can't render non-quads yet.) Perhaps there's also a sense that it takes a lot of effort and patience and some skill to keep it all quads, and the resulting mesh has a more pleasing 'clean' look to it.

But personally I've never noticed any slow-down. As you can see above I've integrated triangles and 5-sides into my modeling method. It's a very easy way to add bumps and discontinuities, and not having to worry about edgeloops is a relief and a timesaver, and keeps the polygonal model slightly lighter. It also works fine with deformations; here's a rigged foot bending:

But if you have other experiences please feel free to share, I'm always eager to learn.

The UV's (I know not very clean), and the texture maps: color, spec, bump.

Another rendering. This is rendered in the default Maya renderer, using depth-mapped spotlights, and my skin shader which you can read about in my skin shading tutorial.

Copyright 2003 Steven Stahlberg

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