Say what you will about performance capture, but Mars Needs Moms (opening tomorrow from Disney) is a definite advancement, particularly for Robert Zemeckis' now defunct ImageMovers Digital studio. Indeed, Zemeckis' style of performance capture (best described by production designer Rick Carter as "portraiture") has come a long way since The Polar Express.

The first thing you notice in this fantasy about a boy who goes to Mars to save his mom and seek redemption for wishing her out of his life is how much better the facial animation is. The skin, the eyes, the mouth, the movement, even taking into account the stylization, are a lot more believable.

That's because IMD went to great pains to improve the facial capture, the rigs, the lighting and the rendering as a result of higher resolution, greater polygonal count and overall accuracy.

For starters, IMD introduced a new system called the Kabuki Mask, which blends the video images of an actor from the four helmet cams and projects it onto a 3D polygonal mask, allowing unprecedented access to the actor's facial performance. Then that gets put onto the body motion or the animation of the character when delivered to director Simon Wells' layout.

"Bob always wanted to create a 3D polygonal mask of each actor but we didn't have the fire power, we didn't have the software, we didn't have the technology to implement it," suggests production designer Doug Chiang, whose greatest challenge on Mars was delineating the difference between a warm and friendly home on Earth and a cold, gray world on the Red planet."So, Bob had to resort to old school technology of a video clip. It was always enough for him to work with but it was never enough to do accurate editing and eye lines. So, on this one, we actually got that to work."

Animation supervisor Huck Wirtz, who recently launched his own studio, Bayou FX in San Rafael and Louisiana, adds that the greater fidelity is a breakthrough. "The guys working on the MoCap side experimented and determined the best poly count and resolution that we could have," Wirtz suggests. "But we couldn't do more than around four characters in a scene at once. It would bogs things down in projecting the image back onto the polygonal mask."

There's an improved facial rig as well, which has gotten incrementally better since Polar Express. On Mars, the rig is more robust and has greater controls, allowing dramatic improvements around the eyes and mouth. "It's about paying attention to little details," Wirtz continues. "Everyone would always say the eyes are dead. I would look at the animation and the eyes were really doing the right motion, but I noticed that the area around the eyes, including the eyelids, weren't mimicking what happens. So we really worked hard. Eyeballs are still keyframed because you can't track them. We hand animate the eyes and that's one of our first passes. Another benefit of the Kabuki Mask was that it provided perfect reference. We ran mouth and skin in a FACS session through our solver. Beyond that, we have a really good muscle-based rig.

"The fact that we weren't going for photorealism is a big advantage. But it still has to look lifelike. For me, if you're going to do motion capture, you should make it look crazy -- stylize it for whatever the director wants. It's about finding that level and taking everything -- the proportions and textures -- to that same level."