Pixel Magic Creates More Than 150 VFX Shots for S.W.A.T.
In S.W.A.T., a police action thriller inspired by the popular '70s television series, starring Samuel L. Jackson (Hondo), Colin Farrell (Street), Michelle Rodriguez (Sanchez), and L.L. Cool J (Deke), a notorious drug lord played by Olivier Martinez (Alex) offers a $100 million bounty to anyone who can free him from police custody.
The Plane Landing Sequence
One of the challenges in this sequence, and in fact the entire movie, was to create visual moments that enhanced the excitement and danger without going "over the top" into fantasy. The story had already demonstrated that an offer of $100 million was more than enough money to induce certain people to risk life and limb. For a climax, how about landing the getaway plane on a bridge in downtown Los Angeles.
Intercut with green screen composites inside the Lear jet cockpit, Pixel Magic's challenge was to animate a CG plane operated by a pilot with nerves of steel performing a dangerous, but controlled maneuver. A flight simulator loaded with the characteristics of the Lear jet was used to pre-visualize various moves. Once approved, the flight simulator data was converted to a 3D move for the plane. The plane was modeled and animated using digital stills as a guide of the hero practical plane that was used on the set. Detailed measurements of distances and readings of lights on the bridge were used to create a 'virtual' bridge lighting and reflection package. The practical photography was digitally match-moved in 3D space. Multiple CG passes were rendered to control lighting, depth, and reflection. In compositing, the plane's strobe lights, heat exhaust, tire smoke for the moment of impact, and camera moves were added to enhance realism.
Once on the bridge, a practical Lear jet driven by a V8 engine was used to simulate stopping and takeoff. However, since a Lear jet lands at approximately 150 mph, the photography was shot under-cranked at 20 fps. This meant that all strobe lights were turned off so that they didn't appear to blink wildly. Ultimately, this was still too slow and digital speed changes were made to many plates. In addition, a Lear jet has thrust reversers to help it stop, which were inoperable on the set. Digital 3D match moves were made of the plane for each shot and CG thrust reversers were animated turning on and off. In compositing, the plane's strobe lights, heat exhaust, and tire smoke were added.
The Helicopter Crash Sequence
The police transport helicopter approaches the Parker Center Helipad past S.W.A.T. snipers stationed on adjacent rooftops. As it approaches, a shot rings out. Then another. And suddenly the chopper is spinning out of control over the heads of our heroes on the rooftop -- spinning down to a fiery crash on the street below.
This sequence, which required back to back cutting between practical and CG helicopters, was achieved by a close cooperation between the special effects crew and Pixel Magic's on-set visual effects supervisor, Raymond McIntyre Jr. Using measurements and digital stills taken on set as reference, a CG helicopter was modeled and animated to match the action.
As the practical helicopter falls towards the men on the rooftop, a CG helicopter, blades hitting the parapet timed to practical explosions and throwing debris over the men diving for cover, takes over and spins out of control above their heads. Multi-pass rendering was used to achieve the correct lighting and depth of the helicopter within the frame. In compositing, shadows cast by the helicopter, CG debris and smoke, and a hand-held camera move were added to enhance the action.
To bridge the time from rooftop to ground, a 360-degree building plate was made from a panorama of digital stills shot from a Condor and composited with a green screen interior of the helicopter. Varying degrees of motion blur were added to the foreground and background to simulate an out of control spin.
Upon reaching the ground, a full size -- but bladeless and smokeless -- helicopter was dropped from 75 feet in the air and exploded on impact. Covered by nine high-speed cameras, including three inside the adjacent office building with windows rigged to explode and one in a taxi that crashes into the helicopter, the challenge for Pixel Magic was to orchestrate a believable eggbeater style stopping of the helicopter blades including interactions with the ground and fire while staying firmly tracked to the helicopter. Detailed measurements taken on set were used to aid the 3D match moving process. Actual footage of crashing helicopters was used as reference. The sequence was pre-visualized and approved by the director. Digital speed changes were made to the practical plates to speed up the action. Multi-pass CG rendering was once again used to control lighting, depth and reflections of the fire in chrome surfaces and blades. In compositing, CG smoke, gouges in the ground, dust, and camera shake were added to enhance the action.