FXGuide has a great article up on the visual effects of The Price of Persia, discussing how Cinesite, MPC, Framestore, Double Negative, and NVizage all worked together to create the many VFX shots in the film. In particular, I love the part about the similarities between crowds and cities.
Drawing on the underlying structure of MPC’s existing proprietary ALICE crowd system, Town Planner gave MPC an initial pass at the city that could be augmented with other surrounds like gardens, streets and trees, as well the surrounding mountainous environment. “Buildings are pretty much a crowd that doesn’t move,” noted Ceretti. “We already had layout tools for the crowds – why not make it similar? In the end, we stripped out everything we wouldn’t need in terms of simulation of crowd motion and just used it for layout, but it was still a huge render so we had to split up parts of the city and bake out different renders in RenderMan to make it possible.” In the end, this amounted to about 20,000 buildings and 180,000 props – things like canopies, piles of wood and pots. For shots of the invading army and other crowds in the city, the ALICE software was used to generate 10,000 agents made up of soldiers, flags, citizens, horses and camels, and then integrated into the city shots. Further projection work was done in both Shake and Nuke to allow for 3D space adjustments and other details to be added, along with the layering of atmospheric dust, mist and rays of light.
