F R O M    T H E    T R E N C H E S Post-Production Report: Visual Effects Revealed   continued...

Cemetary Sequence: Charley's Visit by Ellie's "Ghost"

Ellie's girlfriend haunts Charley in the afterlife. She visits him twice, first at his own grave and later at his own house. In both instances, he can see her but she cannot see him. And after his brief glimpse, she vanishes in a wispy wash of smoke. (A QuickTime movie example of this. 141K)

For the disappearance to smoke, Alias PowerAnimator provided a particle layer of smoke. I isolated Ellie with a matte and then used a simple plane holding the image plate facing the camera and generated particles wherever the matte was white. The color of the particles is derived from the color of the plate itself, making the image seem to wisp away into smoke. I repeated this theme with my opening credits, as seen in the trailer.

Ellie is never fully opaque. For most plates I was able to extract a clean plate by choosing appropriate moments of time -- she was usually moving across the frame over the course of a given shot. For two brief shots, including the closeup crying shot below, I duplicated bits of the frame to the left of her to create a clean plate in Photoshop. These clean plates are then mixed with her matte to make her somewhat transparent.

Her matte was almost never roto'd (well, okay, maybe two shots were roto'd). Instead, I used the clean plate and the running clip and used a difference matte. The strangeness and inaccuracies of this technique usually didn't matter; in fact, it kept her transparency from being too constant across her form.

Ellie's difference matte at a moment in the above shot.
 
 

These sequences work so much better than my rough cut; Ellie truly seems separate, lost from the world Charley is now trapped in.