The Core Effect

When Realism is Not Enough

Gregory McMurry, Core’s visual effects supervisor,oversaw creation of stylized yet believable underwater and undergroundeffects, depicting environments that would normally be murky in thereal world.

Paramount's sci-fi disaster movie, The Core, illustrates the“difference between achieving believability and realism” invisual effects, according to Gregory McMurry, visual effectssupervisor.

A large chunk of the movie's 450-plus digital effects shots, McMurryexplains, show an experimental ship racing through murky water at thebottom of the ocean and then boring into the Earth as rock, dirt, lava,and other debris swirl around it. To portray such sequencesrealistically, he says, would mean audiences would barely be able tosee them.

“In reality, there would be precious little visibility in theocean depths, in the whirlpool scene, and certainly when boring throughrock with lasers,” says McMurry. “It would, in reality, bemurky and cloudy. Therefore, we had to train the audience to accept astylized view of the ship's journey through what would normally be veryopaque, solid backgrounds. That's the true test of the effects in thismovie. Our basic approach was to keep the digital camera close to theship at first, establish a sense of believability, and then move thecamera further away as the ship goes deeper. In the movement of organicmaterial like water, rock, lava, other debris that the audience doessee — keep that in accordance with real physics. I call this thedifference between believable and realistic — it's not realistic,but it's believable in terms of something you can acceptvisually.”

The film's initial November opening date intensified this challenge,creating a hectic initial schedule to finish more than 450 digitalshots — more than half of which are completely synthetic. Therelease was then pushed back to March when filmmakers decided toenhance the ending, giving the effects team more time, but also moreshots to produce. (Shortly before press time, Paramount altered thefilm's trailer because of a sequence showing a space shuttle indistress, coming on the heels of February's Columbia disaster.As of press time, however, studio officials were saying the film woulddebut as scheduled in late March, and the shuttle sequence would remainbecause it shows the shuttle being saved by heroic astronauts.)

In any case, the extensive range of effects seen in the film are averitable potpourri — a series of “topside disastersequences,” including the shuttle emergency landing and thedestruction of the Golden Gate Bridge, followed by the launch of theexperimental ship, dubbed Virgil, and its journey through water,rock, magma, and lava to the Earth's core. To get all this work done,McMurry divided the job among 17 different effects companies.

“Since the types of shots and their locations all vary wildlyfrom San Francisco to Rome to Los Angeles to the bottom of the ocean tothe Earth's interior, we didn't need everyone's work to replicate eachother stylistically,” says McMurry. “And besides, the onlyway to do it on this schedule was to divide up the shots massivelybetween a lot of companies, having everyone work in parallel. Weessentially turned all of the companies into one virtual studio,setting up a secure Internet site to connect all of them to ourproduction. This enabled me to use people all over the U.S., along withCanada and Australia, to get it all done efficiently.”

The primary group of facilities, however, were Creo, Santa Monica;CIS, Hollywood; Frantic Films, Winnipeg, Canada; and Australia's RisingSun Pictures. Frantic was charged with creating a crystallized virtualset sequence — a gigantic, crystal-lined “geode”where Virgil gets stranded — while Rising Sun wasresponsible for creating the shuttle's emergency landing sequence.

According to McMurry, however, the environmental shots produced byCreo and CIS that lie at the heart of the film were among the mostcomplex and crucial scenes to create. Creo primarily handled the launchof the ship from an oil rig and its ensuing journey through the murkyocean depths to the bottom of the Marianus Trench, while CIS handledthe task of showing Virgil drilling its way to the core.

Andy Lesniak, co-CG supervisor at Creo, says the company primarilyused Maya 4.0 to animate the scenes involving the launch and first partof Virgil's journey through water (about 70 shots total) andLightWave 7.5 to render the sequence, along with Houdini's (5.0.46)particle system capabilities and the Arnold (1.2.31) LightWave renderplug-in to detail the “billions” of bubbles that swirl asthe ship interacts with the water.

“Arnold was the only package that could render out that manybubbles individually in our timeframe,” says Lesniak.“Rusty Ippolito [co-CG supervisor] was responsible for theeventual procedure we used to make the bubbles and plumes of air anddebris all look believable. He set up the bubble motions usingHoudini's particle system and then rendered it all together inArnold.”

Ippolito adds, “We had to do extensive R&D on volumerendering techniques to handle this number of bubbles, because incertain shots, they actually cover a huge amount of screen real estate.Sometimes you can do that with a volumetric shader, but this show'soriginal schedule was so short and the render time so extreme that wehad to try a different approach. Plus, each shot involved turbulence,and so the bubbles constantly move in different ways, due to the natureof how we made the ship move through water using what the movie calls‘exo-turbines.’ Houdini let me overcome these issues bytaking the same basic setup, when it was calmer in the water, andmoving those particles with buoyancy, interacting with each other. Thatway, I could take those initial bubble systems, attach them todifferent setups of Virgil moving through the water created inMaya or LightWave, and create different settings for eachshot.”

Frantic Films’ virtual set crystals were combined with lavacreated at Creo, Santa Monica, for the scene in which the Virgilis stranded.

Earlier in the film, when Virgil launches into the darkocean, the froth swirling on the top of the ocean (built in LightWave'sArete water plug-in) needed some augmenting to look believable.Pursuing that goal, Creo artists went down to the Santa Monica pier andtaped swirling surf using a Sony HDCAM (HD-FW900, rented from Bexel,Burbank) and composited texture pieces from those shots together asmattes with the animated water.

“One smart thing we did was budget for an HDCAM and do someR&D on this approach ahead of time,” adds Ippolito.“That gave us the additional 10% realism we needed to put theshot over the top. Andy [Lesniak] tiled out the full-resolution frothtextures from those shots, and our compositing team [headed up by DonLee, Creo's compositing supervisor] put it all together.”

Brian Hirota, visual effects supervisor at CIS, emphasizes that oncethe visual approach to the drilling scenes had been adopted, using thissense of hyper-realism, the effects' team still worked to keep themovement of the pieces of rock, liquid, and debris realisticwithin that framework.

“The debris and rock and stuff fills up a good portion of manyframes during these scenes,” says Hirota. “We werecommitted to making the motion of Virgil pushing through therock material look real. To that end, we employed a computational fluiddynamic solver created by a group of scientists for military andaviation purposes, in order to figure out how machines can move throughwater, air, lava, or any other viscous liquid system, and we applied itto these shots. Their software is called Flow Analysis [manufactured byFlow Analysis, based in New York and Tennessee], and once we tweaked ita bit, it allowed us to apply their data to our volumetric renderer[JIG, from Steamboat Software] to produce a wake effect aroundVirgil, creating physics-based animation that is very realistic.Therefore, although we took liberties in terms of what the viewer canor cannot see, what they do see moves in a realistic way. To myknowledge, Core and the most recent Harry Potter movieare the first two feature films to ever use this technology.”

CIS animated the drilling scenes primarily in Maya 4.0, compositingin Inferno and Shake (version 2.47), and using Entropy (3.1) to renderout hard rock and metal surfaces, and JIG as a volumetric renderer forloose rock and debris.