Taking Up Arms for Battle: Los Angeles
To create the massive destruction, Cinesite applied realistic smoke, dust, fire and water explosions. Physical elements shot on location were composited onto digital matte paintings. Layers of haze, smoke and dust were created in Maya Fluids and Cinesite's proprietary software, csSmoke. The donut-shaped smoke rings seen at various stages are Cinesite's trademark in the film and symbolize the aliens landing. Liebesman set Ben's team the task of creating dramatic but realistic smoke rings after the director was inspired by an explosion on set.
The freeway battle, meanwhile, was handled by Hydraulx. "It contained a lot of infantry alien [fighting] and matte paintings of LA from a freeway overpass as well as the Walking Gun, which is a very unique piece of hardware," Burrell contends. "This was based on the BigDog robot, built by Boston Dynamics. It's basically a canon with legs, and an alien would guide from behind it, firing artillery. This involved lots of tracer fire and bullet hits and matte paintings."
The final battle contains contributions from Cinesite, Hydraulx, Spin and Embassy, in which the marines discover the alien command & control center hidden underground; it unearths itself and the marines have to shoot it out of the sky to stop the signals being transmitted from the center. Hydraulx did the command & control center rising up out of the ground.