Building the scenes and characters to continue the Hogwarts legend.
e all know that Harry Potter must not use
magic around Muggles, but when he’s in
school at Hogwarts, where most of the story in the J. K. Rowling series of books takes place, magic rules. Thanks to hundreds of special effects and visual effects wizards who have created talking paintings, moving staircases, candles floating in the air, a giant spider, a Hippogriff, Dementors, and numerous other creatures, we can see the magic in films based on those books.
For the fifth film, “Harry Potter and the Order of the Phoenix,” visual effects supervisor Tim Burke who won a visual effects Oscar for “Gladiator” and received an Oscar nomination for “Harry Potter and the Prisoner of Azkaban,” cites new creatures and environments as some of the most exciting effects work.
Double Negative and the Moving Picture Company (MPC) were largely responsible for extending the sets, building environments, and creating backgrounds for “Order of the Phoenix.” In addition, they, along with Framestore CFC and Industrial Light & Magic, created new magical creatures, reprised familiar creatures, and created other effects for the film. “We had other vendors as well,” says Burke, “Rising Sun, Cinesite, Baseblack, and Machine, but their work was more compositing and less animation based.”
Double Negative
London-based Double Negative, which landed the majority of the shots, created a 16-foot tall creature called Grawp, who was always CG, the Hall of Prophecies, the Veil Room, establishing shots of Hogwarts, Scotland environments, Death Eaters, Patronus spells, and other effects.
The studio bases its pipeline on Maya and RenderMan, with a touch of Houdini, but for facial rigging uses a proprietary setup based on the facial action coding system (FACS). They also have in-house skin shaders and Rex, a custom lighting interface.
Because Grawp appears in scenes with human actors and because he’s Hagrid’s half-brother, the giant needed to look human. “We had a fantastic level of textural detail in his skin,” says Paul Franklin, visual effects supervisor at Double Negative.
“Basically, 8K texture maps covered his entire body. His hands had separate sets of 8K maps and his face maybe went up to 16K. We could arbitrarily pick any part and increase textures at whatever resolution we needed. We can see skin pores, dirt, cuts he gets from the bushes.”
To have Grawp pick up Hermione (Emma Watson), the effects crew composited greenscreen footage of the actress filmed riding a giant hand attached to a motion control unit, replaced that hand with a digital hand, and then fit the two into the forest. “Compositing was painstaking,” Franklin says.
The most magical environment Double Negative created, however, was arguably the Hall of Prophecies, an infinite room filled with never-ending rows of crystal spheres on glass shelves. Inside the crystal spheres, prophecies in the form of holograms swirl within a plasma gas. “It’s the first time a fully digital set was used in a Harry Potter film,” says Franklin.
Trina Roy used the studio’s dnAsset and dnDynamite tools to create the environment. dnAsset, a Maya plug-in, manages complex geometry, like that in Gotham City for “Batman Begins.” dnDynamite is a rigid body solver built into Asset that effects a dynamic simulation. During a battle between Harry Potter (Daniel Radcliffe) and the Death Eaters within the Hall of Prophecies, the rows of shelves fall like dominoes, creating what Franklin calls a “waterfall of destruction.”
For the plasma, technical director Chris Mangall developed a pseudo-volumetric shader in RenderMan. “It had nested layers with 3D noise textures running through them, animated and offset from each other like the layers of an onion, all sliding against each other,” says Franklin.
To reduce rendering time for the thousands of glass objects, the crew ran ray tracing for refractions between shelves only in close-ups. Otherwise, they used a single ray trace pass for reflections between shelves, rendered utility passes, and created hold-out mattes for the surfaces to add lighting effects during compositing in Shake.
As for the cause of the destruction, the Death Eaters, Double Negative had first created them as swirling clouds of black smoke for “Goblet of Fire.” For this film, they gave the creatures more of a physical shape using Maya fluids and the studio’s volume renderer, with soft bodies in Houdini creating trailing ribbons and cloth. “The ribbons gave them a sense of direction and energy,” says Franklin.
The studio also extended the set for the Veil Room and enhanced a battle inside using an in-house library of bullet hits, explosions and debris. But, nearly 100 of Double Negative’s shots take place in the Room of Requirements, a set filled with old mirrors in which the students practiced ways to battle the dark arts. “The mirrors made roto challenging to say the least,” says Franklin. “We used ‘noodle’ in Shake, but it was heroic work.”
Inside the room, the young magicians cast, in particular, many Patronus spells, each student forming protective animal shapes from light. Animators at Double Negative performed the animals – a horse, otter, hare and dog – in Maya and then the effects crew exported the animated objects into Houdini. In Houdini, they added trailing veils and ribbons off the creatures using soft bodies, exported those into Maya, and shaded and lit them with Rex, the proprietary lighting system.
The studio used the Houdini soft bodies to move away from what Franklin calls a predictable look created with particles and fluids. Instead, they tried to reproduce the optical effects from such earlier science fiction films as “Cocoon” and “The Andromeda Strain.” “You see an organic complexity that you don’t always get with digital effects,” says Franklin.
In addition, the crew found soft bodies much faster to work with than simulation and more easily art-directed. “Soft body animation gave us a direct approach and a stylized feel,” says Franklin. “We could add a vortex effect or a ripple with high frequency through displacement maps. And if we wanted something to hang in the air and slowly dissolve, we could do that quickly.”
e all know that Harry Potter must not use
magic around Muggles, but when he’s in
school at Hogwarts, where most of the story in the J. K. Rowling series of books takes place, magic rules. Thanks to hundreds of special effects and visual effects wizards who have created talking paintings, moving staircases, candles floating in the air, a giant spider, a Hippogriff, Dementors, and numerous other creatures, we can see the magic in films based on those books.
