Primatte Keyer 4 is my new favorite tool. And the reason is shown above. This is actor Kat Carney from a scene in Second Person, now in post-production. The film has dozens of greenscreen shots, but this is one of the most difficult shots to key. In fact, I thought this shot was destined for thecutting room floor – until I used it to test Primatte Keyer 4.
Power
In this scene, the character, Rox Embo, is falling from a tall building to the street below. To shoot this scene, we supported the actor on a table over a green-painted vinyl floor. A fan just below the table wildly blows her hair and costume as she flails her arms and screams. Even when we were shooting it, I thought it was probably a lost cause, because we violated every rule in the book for a clean greenscreen shot.
To begin with, the background was only about two feet behind the actor. So it was dumping tons of green light on her. We couldn’t get the screen evenly lit because of the tight distances. We were in a room with 8-foot ceilings, so the camera was only about 6 feet above her on a jib arm. In the background you can see: (1) three blue registration marks that we needed for angle matching, since the camera wasn’t perpendicular to the ground. (2) The table was too wide and stuck out, so we grabbed a different color of turquoise soundproofing foam to hide the table. (3) The vinyl floor had already been used in many shots and was covered with dirty footprints that discolored the surface. (4) Because the actor is so close to the screen she is casting shadows, on the screen, that are directly behind the detail of her hair, and as she flails her arms it constantly changes the shadows and the ambient light on the screen. Finally (5) we have blonde hair, spread out, moving, and so unevenly lit that it is virtually in a green shadow on the left and in full light on the right.
When we were shooting it, I remember thinking that the moving, translucent blonde hair would be a focal point in the shot (No place to hide a bad key), and that this would be the Achilles heel, and when I got it into post (production) that turned out to be true. As her arms moved, changing the light, and as her hair moved, artifacts would show up and blocks or patches of her hair would just disappear. I tried every keyer I had in After Effects, Final Cut Pro, and Motion. The best key I got, before trying Primatte Keyer 4, involved cutting the scene into seven separate clips, placing them on separate layers in After Effects, and pulling separate keys. This almost worked for the key, but the foreground coloring and the exact edge came out different in each clip.
Was the shot worth rotoscoping? Would hand-cutting around that hair in each frame be worth it? I’ve hand-cut 250+ frames before. Not a lot of fun.
What finally worked for this shot was the ability in Primatte Keyer 4 to animate every parameter. I was able to pull a key, move a few frames, and then set a keyframe to adjust the background matte, foreground correction, and spill suppressor. Then I’d move another few frames and set more keyframes. Primatte Keyer 4 actually interpolated the values between the keyframes, giving a constantly changing key that perfectly matched the changing footage.
