Issue link: https://digital.copcomm.com/i/1144162
40 cgw s u m m e r 2 0 1 9 all, the visual effects are as intense as the performance by the actors (aer famously enduring 11 weeks of night shoots in the icy rain and mud outside Belfast) when the combined forces of the kingdom (minus those of Cersei and Euron) face the Night King and his Army of the Dead. It's a show- down viewers have waited years for! The mighty Doth raki warriors, Unsullied armies, and many beloved knights head toward the foe. A storm rolls across the battlefield, ob- structing the view, then seconds of deadly silence before only a handful of battered heroes retreat back to the castle. Soon the wights attack, held back temporarily by a trench of fire. Meanwhile, Jon Snow and Daenerys launch an aerial attack on the back of Dany's two remaining dragons, Rhaegal and Drogon, but the Night King has a dragon of his own, the resurrected Vise- rion. The battle rages on the ground and in the air, through a fog of war that heightens the action. Half of Weta's approximately 600 shots in the season occurred during the Battle of Winterfell, during which Weta handled the ground attack, while Image Engine handled the episode's dragon animation during the aerial battle (and throughout most of the season). El Ranchito in Madrid also picked up numerous shots in Episode 3. "It is a long, sustained battle," Bauer notes. The Fire Is Lit In this crucial episode, Weta created the armies and the vast terrain, extending the castle, and conveyed the changing balance of the battle through the storm, along with fire and destruction. The studio created 30,000 undead wights and thousands of Dothraki with flaming swords simulated using Massive. Dynamic Massive sims also generated the forces that tossed the wights into the air when struck by dragon glass and fire. Weta – which handled another recent battle, in Avengers: Endgame – helps Melisandre ignite the Dothraki swords near the start of the battle. "That was an interesting challenge because there's a combination of full-CG shots, which are Massive simulations of horses and Dothraki, and some plate shots and combinations to ground the action in reality," says Martin Hill, VFX supervisor at Weta. "The plate shots contained little if any fire on the swords due to the impracticality of shooting that amount of fire with horses on set." For the full-CG shots where the sword placement is known, Weta lit them using 3D fluid simulations. But for the plate shots, the artists leveraged a tool called Eddy, which was written in-house and works within Foundry's Nuke. "When the big wave of fire moves across the Dothraki, some of the swords are LEDs. We stabilized the plates and all the swords with optical flow, then essentially painted on all the timings of how and when the swords light up on a single frame," explains Hill. "Then we used that in Eddy, the fluid solver, by projecting it onto a depth map, getting the full 3D position, and using that light source as a fuel source for the fire simulation." The traditional approach would have been to track all the swords and then track a fire element onto them or do a pre-canned simulation and add that on, or track all the swords and run a full-3D sim. Either way, the process would have been slow and prohib- itive. "It essentially meant we could do the fire sim in the comp. We didn't have to go all the way back to effects to simulate and render again," Hill says. Meanwhile, the big wave of fire that sweeps across the army was full CG placed atop prop swords. One of Hill's favorite scenes was when the Dothraki ride out and attack the wights, and they get annihilated, as evidenced by their torches becoming extinguished. The action is shrouded in a thick cloud that rolls across the battlefield, announcing the arrival of the Night King – but even though the action was obscured, Weta nevertheless did a full Massive simulation on the wights and the Dothrakis falling off their horses. Weta devised a new approach for handling the large-scale volumetrics and destruction used to generate the storm on the battle- field, which still allowed for artistic control. In addition to hero volumetric simulations, the artists also extensively used Eddy to simulate and render 3D weather elements during the composite. The ebb and flow of the battle was then conveyed through the intensity of the graph- ically-driven storm. At one point, the storm is almost like a giant wave, with tendrils, fin- gers, coming toward you, says Hill, achieved using a combination of guide curves within the simulation while also simulating all the physics of the revolving storm. "We got some shots where Dany is riding Drogon, under the wave of the fingers that are coming over, and when Drogon flames, the fire uplights the dragon and casts a shad- ow on the underside of the storm wave," he adds. "So you have this giant dragon shadow following the dragon. It made for quite an im- pressive graphic of the dragon looming over the crowd." For this, Weta used its proprietary Deep Compositing tools to compute the light path through shadowing objects, enabling them to cast accurate shadows on the misty atmosphere of the dragons. Massive also played a big role in the swarming and climbing of the wights as the battle raged on; it also helped disintegrate them. One particularly difficult crowd scene involved more than 500 wights crawling over and attacking Drogon when he is on the ground, injured – a simulation by Image Engine. "The wights are reacting to each other, but they're also reacting to the moving surface of the dragon because he is WETA CREATED THE ARMIES, TERRAIN, AND MORE IN THE BIG BATTLE.