I had the incredible good fortune to cross paths with iq at Pixar; I was an intern while he was developing the Wondermoss procedural vegetation system for Brave. A bunch of us interns were already fans of his work from the demoscene world and upon learning this, he was kind enough to put together a special lecture for the interns on procedural graphics and the work he was doing for Wondermoss. That was one of the best and most mind-blowing lectures I've ever seen- for every concept he would discuss in the lecture, he would live-code a demo in front of us (this was before ShaderToy was a thing, so live-coding was something nobody had ever really seen before), and halfway through the lecture he revealed that the text editor he was using was built on top of his realtime live editing graphics system and therefore could be live-coded as well. One of the things he showed us was an early version of what eventually became the BeautyPi tech demo [0]; keep in mind that this still looks incredible today and iq was demoing this for us interns in realtime 14 years ago.

Wondermoss was a spectacular piece of tech. Every single forest scene and every single piece of vegetation in Brave is made using Wondermoss, and it was all procedural- when you'd open up a shot from Brave in Menv30, you'd see just the characters and groundplane and very little else, and then you'd fire up the renderer and a huge vast lush forest would appear at rendertime. The even cooler thing was that since Brave was still using REYES RenderMan, iq took advantage of the REYES algorithm's streaming behavior to make Wondermoss not only generate but also discard vegetation on-the-fly, meaning that Wondermoss used vanishingly little memory. If I remember correctly, Wondermoss only added like a few dozen MB of memory usage at most to each render, which was insane since it was responsible for like 95% of the visual complexity of each frame. One fun quirk of Wondermoss was that the default random seed was iq's phone number, and that remained for quite a number of years, meaning his phone number is forever immortalized in pretty much all of Pixar's films from the 2010s.

iq is one of the smartest and most inspiring people I've ever met.

[0] https://www.youtube.com/watch?v=_9CZ9UgrcZU

the only mistake iq has ever done in his whole life was to read youtube comments in his amazing videos.

The sting in the phone number tale is that, at one point, he changed his phone number and suddenly all the vegetation changed when scenes were re-rendered.

This is awesome, thanks for sharing this story.

What sort of tech/techniques did wondermoss use? Was it generating polygons?