VANCOUVER — When director Roland Emmerich approached long-time collaborators and visual effects supervisors Volker Engel and Marc Weigert from Uncharted Territory to discuss the visual effects for the film White House Down, in his mind it wasn’t a large undertaking at all.
To Emmerich, who directed such epic visual effects-driven films as 2012, The Day After Tomorrow and Independence Day, this was primarily an action film that would require, at most, a few hundred visual effects shots.
For starters, the iconic dome of the Capitol building needed to be blown up, burned and then collapsed, and later three Blackhawk helicopters needed to be shot with surface-to-air missiles before crashing spectacularly into various parts of the White House’s South Lawn.
Method Studios (www.methodstudios.com) was a natural fit for this kind of work, having a proven track record with CG simulated destruction and pyro on projects such as Vampire Hunter, Wrath of the Titans and G.I. Joe: Retaliation.
But the screenplay also called for a lot of the action to take place on the White House grounds, on the roof and in the air above. It’s not feasible to shoot in the Obamas’ backyard, and it’s prohibitively expensive to recreate a set on a large scale, so inevitably this increased the tally to upwards of 900 visual effects shots.
Engel and Weigert realized that the work would need to be divided between multiple vendors, but this posed a problem, as much of the action occurs in the same place. Twelve different vendors, with 12 different pipelines, would need to share the same CG assets in order to maintain consistency.
Method Studios, as lead vendor, was responsible for creating a photoreal CG White House and White House grounds, along with its fountains, buildings and trees, plus the surrounding parks, buildings and skyline of DC. In addition to Method and Uncharted Territory, other studios on the film were Prime Focus World, Hybride Technologies, Luxx Studios, Image Engine, Scanline VFX, Crazy Horse Effects, Trixter, Crafty Apes, Factory VFX and Fuse FX.
The trees proved to be an interesting logistical and technical challenge, due firstly to the sheer amount of geometry required to represent all the individual leaves and branches of each tree, and secondly the sheer number of trees required to accurately recreate the surroundings. A further complication was that the trees always needed to be moving — whether swaying gently in the breeze, being blown about by helicopter rotor wash, or, in one of the film’s most ambitious shots, believably interacting with a crashing Blackhawk and its still-spinning rotors.
Ollie Rankin, (pictured) VFX supervisor at Method Vancouver, recalls the process of assembling that particular shot. “It required a dedicated team of technical artists and practically an entire pipeline unto itself. There was a long chain of dependencies and we knew that we needed each step in the process to be as procedural as possible in case anything had to change upstream.”
A sophisticated animation rig was built in order to reveal successive stages of damage as the helicopter first hits the ground triggering an explosion, then hits the tree at which point it breaks apart, before the remaining fuselage rolls onto its side, burning, and comes to rest. The animation was done in Autodesk Maya and cached out using the open source alembic format. This cache was used to light and render the helicopter in Maya and V-Ray, but it also drove the various simulated effects: fire, smoke, explosion, disintegrating tree and torn-up ground. In turn, the dynamic tree, controlled by a combination of wire deformation and rigid body simulation in Side Effects Houdini, was cached out for lighting, while the deforming ground went through an additional process to dress it with grass.
On top of that, leaves, grit, dust and blades of grass were simulated, being blown about in the turbulent wind. Every one of these elements needed to cast shadows on one another, as well as the fire and explosion needing to cast light.
Another strategy employed to protect against the potential catastrophe of last-minute changes was that all the various objects and their shadows were rendered separately as deep raster images. This decision really paid off when an animation change was required less than a week from the deadline. Rendering “deeps” is computationally expensive and they take up a lot of disk space, but they eliminate the need to cut foreground objects out of background objects when rendering, meaning the background doesn’t need to be re-rendered every time the foreground changes.
The smallest sequence on Method’s plate — in terms of shot count — required some of the most elaborate simulated dynamics. The brief was to portray a bomb exploding inside the Capitol dome, knocking over and engulfing the people inside, expanding to fill the dome and blowing out the windows. The explosion and resulting fires ultimately cause the entire dome to collapse in a subsequent scene.
Back in 2011, Method developed a proprietary CG pyro toolset within Houdini for their work on the burning bridge scene of Abraham Lincoln: Vampire Hunter. This toolset has since been updated to take advantage of the latest features in Houdini and was used not only to simulate the explosions, fire and smoke plume for this sequence, but also for the three helicopters being blown out of the sky. The dome collapse was achieved using a carefully choreographed rigid body simulation in Houdini, with multiple layers of smaller debris and dust reacting to that primary simulation.
In total, Method delivered more than 170 VFX shots. “The great thing about these clients,” Rankin explains, “is the amount of artistic freedom they allowed us. There are many different ways of interpreting the brief for a shot, and they were open to our ideas, which meant we could really engage in the work creatively.”