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Pixel Magic Casts Out VFX For Exorcist: The BeginningCreates 28 visual effects shots for the much-anticipated horror prequel (August 23, 2004)
Pixel Magic today announced it created 28 visual effects shots on the much-anticipated horror prequel, Exorcist: The Beginning, opening August 20, 2004. Keeping true to the tumultuous legacy of previous Exorcist productions, this new installment was no stranger to major production obstacles. In the works for years and with no less than 3 directors taking turns at the helm, the upcoming theatrical release features over 400 visual effect shots.
Exorcist: The Beginning serves as a prequel to William Friedken's original 1973 blockbuster. Set in post World War II Africa, the story traces Father Merrin's first encounter with the demon Pazuzu. Taking advantage of huge strides in digital visual effects technology since 1990's Exorcist III, this film features some spectacular large-scale effects shots. Visual Effects Supervisor Ariel Shaw chose Pixel Magic to handle the most ambitious shots of the opening sequence, as well as key shots involving CG doubles for actress Izabella Scorupco. Led by Visual Effects Supervisor Ray McIntyre Jr., Visual Effects Producer George Macri and CG Supervisor Micheal Hardison Pixel Magic delivered 28 of the challenging shots.
Setting The Stage
The opening sequence of the picture, set at the time of the Crusades, shows an exhausted priest staggering through the aftermath of a massive battle. Throughout the sequence, the desolate landscape is littered with corpses and raked by blowing sand, many of these elements added in postproduction. In a dramatic move starting on the priest's horrified reaction, the camera pulls back through a sea of inverted crosses each bearing a soldier's corpse, slowly rising up to reveal the massive landscape - hell on earth for as far as the eye can see.
The live action photography for the sequence was shot in a quarry-like location in the Moroccan desert. In order to achieve Harlin's vision of an endless battlefield, Pixel Magic replaced the rock wall background with matte paintings of an expansive desert environment riddled with rocky outcroppings. An army of CG corpses was modeled with different clothing, armour and weapons to populate the battlefield. Positioning thousands of corpses by hand was not a practical solution; instead a technique referred to as 'instancing' was used to automate the process, while still allowing the artists to control the placement of individual corpses whenever necessary. "Instancing allowed us to add over 18 million polygons with minimum impact to the scene's management and render times" reports CG Supervisor Micheal Hardison. "The level of detail we were trying to achieve could not have been possible without the use of instancing," CG gusting dust conforming to the ground plane was added to shots, as were CG flying crows.
The last shot of the opening sequence - the giant pull back to reveal the whole battlefield - proved to be the most challenging. Over 30 seconds in duration, the shot involved compositing a single camera move that moves seamlessly from the live action plate of the priest to a full CG battlefield environment and back to another live action plate as the camera comes to rest on a hilltop overlooking the scene. The live action plates of the priest and a number of performers and dummies portraying the crucified soldiers required rotoscoping since blue screen use was very limited on set. Boujou Bullet and hand match moving were used to 3D track the plates.
The geometry of the CG battlefield environment was derived directly from topographical maps of deserts. Pixel Magic shot reference photos that were used to create the ground texture maps. Since the scale of this landscape was measured in miles, creating high-resolution mesh and textures for the entire CG landscape was impractical. Once the CG camera move was locked down, the landscape geometry and texture maps were finalized with lower levels of detail in the distance and higher detail close to the camera path, which allowed for a very acceptable tradeoff between render quality and render time. Special attention was paid to areas where live action ground was adjoined to its CG counterpart. Additional CG elements (weapons, corpses, shields) were placed over the seam to avoid any potential for visible tracking mismatches.
CG corpses were added to the CG battlefield environment, as they had been in many of the earlier shots. However, the massive scale of the pullback shot, coupled with the dynamic camera whipping by crosses required more subtle animation of the CG elements. A small percentage of the crucified soldiers were given subtle limb movement and cloth rags that fluttered in the wind, while some of the corpses on the ground were animated to be in their final stages of dying and collapsing.
Multiple layers of CG gusting sand were then composited into the shot, taking care to not obscure the hilltop view across the battlefield at the climax of the shot. Visual Effects Producer George Macri sums it up, "Once we added the final elements -- fire, smoke, weapons, horses, flying crows -- we were definitely surprised by the scope of the shot. We had to watch it countless times just to see how the individual elements worked together in the composite. With over 150 CG elements in this one shot, it was a real exercise in logistics".
The Spider Walk Revisited
Omitted from the original theatrical release of the Exorcist and brought back in the 1999 re-release, the 'spider walk' remains one of the most eerie scenes in cinematic history. Harlin made use of recent advances in photo-realistic CG doubles to take this concept to the next level in Exorcist: The Beginning. Towards the end of the film, Father Merrin uses the power of God to throw the possessed Sarah across a cavern and up against a rock wall, where she spider walks across it in a scene reminiscent of the original.
Pixel Magic was contracted to provide a CG double of Sarah to perform the physically impossible spider walk in two shots from the sequence. The first shot begins with Sarah's CG stunt double close up to camera, flying backwards in a dramatic arc across the cavern to landing half way up the rock wall in the distance. With her head and body facing away from the cavern wall, she then begins to scuttle across the rock. The second shot follows her crabwalk as she disappears into a shadowy crevice in the cavern's ceiling. Cyberscans of actress Izabella Scorupco and her costume done on location served as the starting point for Pixel Magic's work on these shots. In addition to making the CG double's skin and face appear photorealistic, simulating the character's flowing dress and hair during her flight across the room and the inhuman articulation of her joints required the company's CG team to use specialized approaches to achieve real world dynamics.
The 'fly back' shot was initially planned as a transition from Scorupco's stunt double being pulled backwards through the air on wires over a greenscreen to the CG double, who would then land on the wall and begin the crabwalk. A practical plate of the wall was shot for the background element. While using the live action stunt double for the first half of the shot would have spared the artists from having to detail photorealistic CG skin and dress close to camera, the difficulty of achieving a seamless transition from the stunt person to the CG double seemed to outweigh the benefits. Furthermore, animating the CG double over the background plate so that her body movements would conform to the subtle outcroppings of the practical rock wall was more challenging than simply reconstructing the rock wall as a CG element. As Pixel Magic's Ray McIntyre explains, "Although going entirely CG for this shot initially sounded like a daunting task, it actually gave us more control and precision in having proper shadow casting, lighting and animation as Sarah moves over the rock wall. We did spend more time on Sarah's textures to ensure they would hold up close to camera, and are pleased with the result".
A CG double was always planned for duration of the tighter shot of her spider walking on the wall. As with the fly back shot, a CG rock wall was constructed through reference to the practical plates, to ensure tracking, lighting and shadows would all interact properly with Sarah's animation. The character's animation rig deviated from that of a normal human because, during blocking meetings with Renny Harlin and Ariel Shaw, it was determined that Sarah's limbs should bend as unnaturally as possible yet remain convincingly human. Pixel Magic referenced several images of contortionists while developing the rig. Subtle irregular head movement and facial expressions were added as secondary animation to the eerie spider walk. Finally, small CG rocks and dust were added to the key points where Sarah contacted the wall to make the shot even more convincing.
Dismount From The Cross
Worth mentioning is one other shot in which a CG double was integrated into the scene in place of practical elements shot on a stage. In one of the more spine-chilling sequences, possessed Sarah is hanging from a cross by her feet. She begins to right herself by bending backwards at the waist, until her body is bent - in the wrong direction. Closeup shots from this sequence were done practically by compositing a pair of greenscreen elements of a stunt double hanging from the cross by her feet and lying on a downwards slant board bending her body upwards. When cut together, these shots depict Sarah bending backwards until the back of her head touches her buttocks. However, the point where Sarah jumps down from the cross became a challenge. The character was required to lift her arms up above her head to hold onto the cross, swing her legs back underneath her body and then drop to the ground. Greenscreen elements of the individual animation pieces were filmed for this, and a composite was attempted without CG. After some rough composites, it became clear that seamlessly blending 3 or 4 different greenscreen bodyparts, all with noticeable lighting differences, was going to be nearly impossible. Late in the postproduction schedule, a CG double approach to the shot was initiated.
Although Pixel Magic no longer had to face the issue of blending multiple greenscreen elements in the shot, this solution was not without its challenges. As they had not intended to use a CG double for the shot, bending their existing CG Sarah model backwards to match the already finished composites in the other shots resulted in some unexpected behavior in the geometry of her CG dress. Sarah's cleavage and collar line were much larger than they looked in practical plates, and would have resulted in a major continuity issue. Redesigning the dress late in the schedule to accommodate this specific action was not a feasible solution. Instead, a greenscreen plate of the actress's head and the torso of her dress were combined with the CG double. A tremendous amount of subtle morphing and match moving was then required to blend the practical head and part of the dress onto their CG counterparts. "It was a tedious process," says McIntyre, " but we ended up with her real head and dress cleavage, which of course had real-world lighting, hair, cloth dynamics. There's nothing to dispute with that, and, if anything, it made the CG body look that much better."
Pixel Magic used Pentium 4 based workstations running Newtek's Lightwave 3D software for the opening sequence, and Alias Wavefront Maya 6.0 Unlimited for rigging, animation, and hair dynamics for shots involving CG Sarah. Sylfex Cloth Simulator was employed for all dress dynamics. Compositing was done on Apple's G5 platform using Adobe After Effects and Apple Shake.
About Pixel Magic
Pixel Magic, a division of OCS/Freeze Frame, spans two generations of expertise in the creation of visual effects for film and television. Services include compositing, 3D & character animation, wire & rig removal, digital film & hi-def restoration, matte painting, main titles, digital opticals, digital trailers, HD/tape to film transfers, film scanning and recording.
Pixel Magic is currently working on "Pink Panther," "Into The Blue," and "Be Cool" for MGM, Columbia Picture's "Spanglish," and "Elektra" for 20th Century Fox.
Related Keywords:Pixel Magic, VFX, Exorcist: The Beginning, Ariel Shaw, Ray McIntyre Jr., George Macri, Micheal Hardison, compositing, rotoscoping, Boujou Bullet, Newtek, Lightwave 3D, Alias, Maya, Sylfex, Cloth Simulator, Apple, Adobe, After Effects, Shake, OCS/Freeze Frame,