James Cameron’s “Avatar: Fire and Ash” picks up where “The Way of Water” left off. The Sully family is hiding as they deal with the loss of son Neteyam (Jamie Flatters). When they take Spider (Jack Champion) to live with the Wind Traders, Varang (Oona Chaplin) leads the Ash People in an ambush on the convoy. The ilu, a sea creature that is ridden by the Na’vi, is also employed in the action sequence. In all, “Avatar: Fire and Ash” needed over 3,000 visual effects shots.
Weta FX senior visual effects supervisor Eric Saindon breaks down how some of the key scenes
came together.
Kiri, Spider and the Ilu
VFX Progression Frames from “Avatar: Fire and Ash”
20th Century Studios
“Our live-action plate of Jack Champion was filmed in a shallow pool in New Zealand. The actor was seated on a camera-ready saddle, while the ilu’s motion was performed by our stunt team in blue suits, LED screens were reflected into mirrors to project the surrounding environment and reflections onto the water surface,” says Saindon.
Excavators were operated with slightly offset timing and fitted with practical paddles designed by Steve Ingram’s SPFX team to generate gentle, overlapping waves characteristic of a protected bay.
“Using our in-house live depth compositing tools, James Cameron was able to view a real-time
composite of the live-action and CG worlds. The same setup also allowed us to generate per-frame geometry of the water surface, which was used to drive the FX simulations,” he says.
“For the final composite, rotoscoping was used to extract Jack Champion and all water interactions from the plate. The matched FX simulation was then combined with a CG lower half for Jack and the underwater elements. The full CG environment and Kiri were added and composited together, with depth-based haze and physically accurate depth of field applied.”
Tulkun Council
For the Tulkun council scene, the animation team animated the Tulkun — huge, whale-like sea creatures — rising through a blocking simulation of the water surface. The simulation calculated momentum and volume displacement as the Tulkun ascended and broke through the surface.
“As the Tulkun breaks the surface and displaces water, the resulting volume is coupled into the simulation, generating bulk water motion and splashes that affect the surrounding ocean surface,” Saindon says. “Thin-film simulations were used to model water running along the Tulkun’s surface and reintegrating into the bulk water simulation.”
He notes that water shed from the Tulkun’s head transitions from the bulk simulation into splashes, mist and atmospheric spray, driven by velocity and prevailing atmospheric conditions.
“For the final composite, our in-house renderer was used to compute physically accurate atmospheric haze. Depth of field was set based on the lens data, and all compositing was performed using deep data,” he says.
