Graphics Reference
In-Depth Information
in Hollywood, and Gabriel Sanchez, 2D supervisor fromLOOK Effects in Los Angeles,
discuss various aspects of video editing and compositing.
RJR: In what kinds of situations do pieces of two video sequences need to be seamlessly
merged, and how do you handle them?
Lambert: That kind of thing is all about slight of hand. The easiest thing is if there's an
element in a shot that passes behind something like a telegraph pole. That pole is the
natural place to draw the dividing line between the two pieces of footage, especially
if the element isn't really where the viewer's expected to look. If there's no pole, it
makes sense to pick a flat area with not a lot of detail to draw the seam.
Suppose you've got a stunt, like a guy's on a motorbike doing a big jump and
there's a big explosion behind him, but the stuntman obviously doesn't look like our
hero character since you don't want to put your A-list actor in danger. Nowadays you
could probably do it all in CG, but years ago you could try to match a take of the
actor's head onto the real footage as well as possible. But you've got this explosion
going on, with light coming frombehind, so ideally you'dwant to shoot the actor with
roughly the same color light. You'd have had to draw a roto spline and fake it in, but
if done poorly it can look very fake since the lighting is very tough to match.
For both TRON: Legacy and The Curious Case of Benjamin Button , we did a lot of
splicing a CG head onto a real actor's body. We'd always roto along the actual collar
line and just replace the neck and head. If you have a shot where that neckline's
going into shadow, into the noise floor of the camera, you'll never be able to find it
and you just make it up. You take the curve and just imagine what would happen.
With TRON , the roto of the collar was easier, since the neckline on the character's
bodysuit was basically a rigid piece of plastic, so you knew it always had a certain
shape. On Benjamin Button , it was much harder since the character woremany types
of different, natural clothing— in some scenes he was wearing a flimsy shirt. In some
sequences where the body double was moving around a lot, we actually had to roto
the collar and warp it around. Those shots took the longest to do in roto, paint, and
compositing—sometimes we'd have tomake up thewhole inside of the shirt because
the body double was wearing a kind of blue hoodie that reflected color back into the
shirt in the original plate. Plus once we put the CG head back in, theremight be a gap,
so sometimes we'd have to clone that piece of texture and track or warp it in; that was
all done by hand. It was very intensive work.
Sanchez: Generally if you're doing a split-screen composite, you're going to have
someone experienced on the camera, but sometimes the camera will slightly move
between the two takes, say because someone kicked the cable. A bigger issue is that
some things may change in the scene between takes. For example, say we're filming
at a sports bar and you have TV monitors and tables everywhere. Now we want to
combine take 1 from when the actor's in a dark shirt with take 20 when he's in a
light shirt, and between all those takes a table or chair in the background moved,
or somebody walks across the scene in take 1 and we've got to carry that motion
through.
In my experience, when two shots need to be split-screened together, I have to
analyze and a lot of times eye-loop the footage, and I just stare at it before I determine
Search WWH ::




Custom Search