"The Hobbit" finale is bracketed by the dragon Smaug’s destruction of Laketown and the eponymous series of battles that occur on multiple fronts and take up the entire third act. For Laketown, Weta Digital ran all the buildings through different levels of destruction. It was like dropping a ball on them and letting them get crushed. Weta used the in-house fire simulation engine called Odin and then ran it through Synapse, the software for volumetric effects. Then they tied in the flame effects during the destruction.
"The flame thrower effect from [Smaug’s] breath was hard," says Letteri, the four-time Oscar winner and Weta’s senior VFX supervisor, who has both "Dawn of the Planet of the Apes" and "The Battle of the Five Armies" in contention for the VFX Oscar. "He’s traveling at supersonic speeds so you have to do tricks at simulating the flame at realistic speed and then figure out how to move the whole thing with the dragon [voiced again by Benedict Cumberbatch].
"The rest of it was managing sheer volume of fire and smoke and destroyed buildings because there aren’t too many shortcuts you can take. Peter kept reminding us that if you have a firestorm of this size on wooden buildings, it’s going to create updrafts and whirlwinds and be very chaotic so we came up with these fire tornadoes spinning throughout the city and in the background."
To help Jackson plan the complicated battles, Weta wrote a new tool called Army Manager, which provided a quick and efficient way of laying out how battalions and other groups would move. "It was great because we could put thousands of characters in real-time on stage so Peter could do his virtual camera work and see these guys in the background, sometimes even in the foreground and use it for choreography.
But to meet the demands of such additional complexity, Weta Digital created a new renderer called Manuka (the name of its Wellywood street), which lit the film with greater efficiency and consistency.
"It’s hard to think of the extra light that you craft onto the scene and about making that work in a believable and efficient fashion," suggests Letteri. "That takes a lot of time and effort to do that and you end up doing it in a bulk fashion.
In parallel, Weta wrote a hardware preview lighting tool called Gazebo that can be used for blocking on stage or at an artist’s desk. "All the shaders and lighting algorithms work the same as Manuka so you get the same results," says Letteri. "But you don’t get all the indirect illumination. It’s been optimized for real-time and for speed. It’s particularly useful for big scenes. You hit the Manuka button and get the same result only more refined. We could not have gotten through the battle scenes [in ‘Five Armies’] without this combination of Manuka and Gazebo."