1. Split vs. average

- Hi. I'm Alonso Martinez and I'm a Character modeler here at Pixar Animation Studios, and that means that I create the virtual characters that the animators use to bring our characters to life. And if I do my job right that means that not only will people believe that they're real, but also they'll become personal friends. Right now I'm standing at the Pixar Art Gallery and this place is dedicated to celebrate all of the hard work that goes into making these movies great. It's important for all departments here at Pixar to help with the story telling. And for the character department, when we design our characters, we tell story through the shapes of our characters. One of my favorite examples is from the movie Up, and that's because Carl is designed like a box and that's because he's jailed in with all of the emotions from the hard times that he's had in life. But Russell is shaped like an egg. Both of these are symbols for who these characters are. To create great characters like these, we need to make tools that are easy for artists to create those shapes that we were talking about. And also, at the same time, for them to be efficient for the computer to be able to deal with all of that data. And that's the topic for this lesson. Stick around for more. In the Environment Modeling Lesson we saw how to describe blades of grass using parabolas, but parabolas are just not good enough to describe the expressiveness of characters. For example, here's a sculpture of Geri's hand from Geri's Game. To describe complex surfaces like this, that's where subdivision comes in. And as we saw in the previous video, subdivision is extremely expressive. In the first part of the lesson we'll be looking more closely at how subdivision can be used to create complex shapes. And then in part two, we'll dive more deeply into the mathematics of subdivision. Most of the mathematics we use here at Pixar have been around for hundreds or thousands of years, but subdivision is different. It was actually only invented about 40 years ago and is still an active area of mathematical research. The skins of our characters live in three dimensional space, but for now, we're going to look at curves in two dimensions. Starting with a four-point polygon, we add more points by Splitting, that is, by adding mid-points to the edges. I can make it smoother by moving each point from where it is now, to the mid-point of its right neighbor. We call this, the Averaging step. By repeatedly Splitting and Averaging, we create a series of increasingly smoother curves. Now, imagine that you're an artist at Pixar and you've been asked to create a shape like this one. Using this next interactive, see how close you can get.