The movie Legion opened in theaters today and shows an apocalyptic world where God sends angels down to eradicate mankind.  Creating these angels proved tricky for VFX supervisor Joe Bauer (not to be confused with Jack Bauer) and his team who initially began with heavy prosthetic wings, but quickly transitioned into CG wings.  Popular Mechanics discusses how they integrated LED trackers, principal photography, and the incredibly detailed 3D models of the wings.

Animators began by studying high-speed footage of owls and hawks in flight and swooping down on prey, which was essential in determining how wings and feathers move. “You can really tell how the air moves through the wings,” Bauer says. “They’re not rigid at all. The wings are always adjusting subtly and the feathers are always reacting to the wind.” Animators combined the coolest characteristics of owl and hawk wings to create the angels’ wings; the end result were hawk-shaped wings that behaved like an owl’s, Animators built them from the inside out—Bauer says there are over 20 layers to the wings, including bones, musculature, feathers, black densities, saturation and lighting, among others. “When you don't have those layers … that’s what makes the difference between wings that look very plastic and cartoony versus ones that look as though they were in the room with the actor on the day of photography,” Bauer says.

via How Legion Movie Wing Animation Works – Popular Mechanics.