Troy (left) and Alexander exemplified massive environments and crowd reconstruction. Troy © 2004 Warner Bros. Ent. All rights reserved. Alexander © 2004 IMF Internationale Medien und Film GmbH & Co. 3 Produktions

Buf also had to put large 3D armies on shaky backgrounds filled with dust clouds. Since the hectic pace of filming in Morocco did not lend itself to setting up a motion capture facility, Buf chose to go for a simple "video motion capture" system consisting of four small video cameras filming stuntmen fighting, running and doing all kinds of battle moves. Horses and war chariots were also captured. Everything was then rotoscoped to produce 3D animation files, which were used in lieu of standard MoCap recordings. This basic system turned out to be really efficient and was used to produce all the animation for Alexander’s armies.

In line with its desire for simple practicality, the Buf team also decided not to use an artificial intelligence-driven crowd system. Instead, it used a series of simple scripts to drive battalions of soldiers on the 3D battlefield, a solution that proved very flexible as it allowed for the hands-on direction of every army move. Combined with the energetic and documentary-like cinematography, it makes for extremely realistic and immersive battle sequences.

But Imageworks also had something to say about massive environments. For the first Spider-Man, Sony had opted for a simplistic city reconstruction based on low-res geometry and highly detailed textures. This time, the team decided to go for ultra-detailed high-resolution modeling of each building teamed with impressive texturing. For example, skyscrapers' offices were textured with different environments and rigged with several illumination systems that could be controlled to produce various daylight and nighttime effects. Though not technically groundbreaking, the amount of work and care put into this reconstruction was quite impressive.

Bluescreen Feature Films
The rendition of highly realistic environments and sets is no longer a problem today, and as it opens new avenues to filmmaking, it was surprising not to see an Imagina session dedicated to the subject of "bluescreen filmmaking." It would have been interesting to compare the varying experiences of working on The Polar Express and Sky Captain and the World of Tomorrow (two films represented at Imagina) with the latest works of director Robert Rodriguez (Sin City and The Adventures of Shark Boy & Lava Girl in 3-D) and the French film Immortel, all films having been shot nearly exclusively on bluescreen, in order to understand the stakes this kind of filmmaking represents, the new opportunities it affords and its limitations today.