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.

"Once the marines hit ground, we travel into Luma territory, the ambush in the smoky street," Burrell adds. "That involved a lot of tracer fire and battle enhancements and some alien shots. Then Hydraulx did the reveal of the alien in the swimming pool. The next crucial scene is the helicopter crash at the police station, which was done by Soho. It's a pretty big, dramatic scene where some of our wounded marines are being evac'd out and an alien ship fires on them and kills everyone on board. The next set piece is the gas station, which has the drone done by Embassy, which is one of the alien ships. It's like a big, round pizza and each slice is like a different ship. One of the drones separates from the main UFO and investigates a bus that our hero, Nantz [Aaron Eckhart], is traveling in. He tricks it by putting a walky-talky near a gas pump and throws a grenade at the gas pump when a drone comes to investigate. That's when we learn the drones are not piloted."

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.

Burrell says most of the vendors customarily started with Maya and then wrote their own shaders and scripts (Embassy uses Softimage). Most also used Nuke and rendered with RenderMan or mental ray.