Ocean Spray: A Tidal Wave Rocks New York in Deep Impact
For the new DreamWorks release Deep Impact, the visual effects team atIndustrial Light + Magic was required to sell audiences the BrooklynBridge-or at least a convincing impression of it. In a climactic scene inMimi Leder's latest directorial effort, a 1,000-foot-tall wall of water,traveling 200 mph, destroys several Manhattan landmarks with tons of foamand spray.
While the film is actually more story-driven than effects-driven, accordingto ILM's Oscar-winning visual effects supervisor Scott Farrar, "the effectsshots they do have are really big!"
One shot in this sequence featured the wave taking out the Brooklyn Bridge,and then moving off into the distance, breaking up the skyline withgigantic bursts of water. In preparing for the shot, Farrar recalls, "westudied destruction movies and lots of films showing atomic explosions.What's really hard about this stuff is that you have to be ever vigilantthat you're not making something up that reads false to the eye."
The aerial shot of New York chosen as the background plate was a chopperflyby overseen by Farrar himself. After completing all the 'hover shots'depicted in the storyboards, Farrar used his last 100 feet of film to graba more dramatic view. "I thought, let's just fly by the bridges, 'causethat's always really kinetic. Of course that became this shot."
Back at ILM, he explains, "we then put in a plastic shader, as we call it,which is a really rough shape of a wave-just a big green wedge that wouldbe animated to slide along at a complementary angle to the camera and theflight line of the helicopter. The tricky part was that the bridge was atan angle to the camera, and we wanted to have a closing distance where wewould feel the wave engulfing the bridge, overtaking the speed of ourhelicopter. The wave is moving towards the camera through the whole shot,so we've got several vectors happening." Along with the CG wave, notesFarrar, "everything was completely built in the computer-the bridge, thebuildings, the cars and the debris." The modeling software used was Alias.
The next step was to take the real bridge out of the plate and replace itwith the CG model. The question Farrar faced was "into how many piecesshould it break apart? We tried different things. In one, the cables werebroken at one end; the whole thing whipped out of the way or got pushed bythe wave. But that looked too rubbery. The bridge, because it's so heavy,simply can't be displaced that quickly. So we finally went to an effectwhere the pieces get laterally thrown out of the frame like piano keysbeing blown apart. Meanwhile, the cables that are broken have kind of awhipped motion to them." This look was achieved using Softimage and ILM'sproprietary code.
"Once that animation seemed right," Farrar recalls, "the next task was toput lots and lots of blasting mist around the parts that were breaking, andat the intersection of the wave against the water. Otherwise it's just aflat plane intersecting the bridge." Using Wavefront Dynamation particlesystem software,the ILM team wrapped the surfaces continuously withemitting particles to represent foam. Farrar notes that lead TD DavidHorsley "did an amazing job-he plumbed the depths of particle behaviorregarding puff-ball foam!"
Farrar likens particle system procedures to "setting up lawn sprinklers-youdecide when they'll turn on, how big they'll be, how long they'll run, howfar they'll fly and what their vectors will be. You turn it on and run itovernight, but you never know what it will look like exactly-sort of likeleaving your house and lawn for six months and hoping you haven't missed aspot!" He stresses that along with the more automated work, "this showreflects incredibly intensive hand-done work. We had 'swat teams' of rotoand paint people descend on each shot, because without them you can't makethis work."
"Finally, the sky had to be replaced," notes Farrar, who had filmed theoriginal background plate on a sunny day. "We needed a dark, moody,threatening sky. That was pretty well concocted using lots and lots ofstill photos to create multidimensional, moving clouds. My philosophy is toimport from photos if possible because they automatically give you complexcolors, details and grain. We also had to apply moving grain." The imageprocessing of the sky was done on a Flame and the final image was renderedusing RenderMan.
When all was said and done, this sequence in Deep Impact had water shotscontaining several million particles, even more than was required for ILM'swork on Twister. Despite the huge size of the studio's computer power,Farrar reveals that at one point in this show "we used every processor wehave!"
Mimi Leder, director; Scott Farrar, visual effects supervisor; Denise Ream,visual effects producer; Ben Snow and Michael Bauer, CG supervisors; DavidHorsley and Hayden Landis, technical directors; Rita Zimmerman, SabreArtist (Flame); Philip Alexy and Jason Ivimey, animators