Pre-Vis

Digital technology is narrowing
the gap among the three primary
divisions of filmmaking—preproduction,
production and postproduction—
turning the entire process
into a seamless pastiche of
unified elements.
Nothing exemplifies this merge
of phases better than previsualization—
the use of CG graphics to
preview the director’s vision and
define the technical demands of
any given scene. Originally used
primarily as a tool for planning
costly visual effects sequences,
previs is now brought on as a
general blocking tool that goes far
beyond the capacities of traditional
storyboards. It’s no wonder that
previs companies are sprouting up
with increasing regularity—independent
companies such as Pixel
Liberation Front and Proof, as
well as in-house previs facilities
at effects and production companies
such as ILM and Uncharted
Territory.
The question is not what is
previs—but what will previs ultimately
become?
Visual effects supervisor Hoyt
Yeatman was on the scene at the
inception of the previs, when the
concept was still a simple question
of conveying the director’s idea of
what would ultimately appear on
screen. He has seen the development
and describes it thus: “Previs really
started back with lipstick cameras,
when it was very organic,” he says.
“We would use brown paper and
foil and foamcore—very basic—
and make miniature sets for films
like Crimson Tide and The Rock,
which I did for Michael Bay. We
did these things real simple, down
and dirty, but
what it allowed
was for people
to participate
very quickly
and interactively.
Then, as
visual effects
matured, the
idea of 3D CG
previs came
into being. The
idea is to predict what you’ll need
and not spend hundreds of thousands
of dollars that wind up on the
cutting room floor.”
VFX Oscar-winner Volker
Engel (Independence Day) of
Uncharted Territory is currently
in post on Kingdom of Twilight, a
Lord of the Rings-style story with
650 visual effects shots. Engel
believes in having the same people
do the previs that will also do the
final visual effects shots.
“In Kingdom of Twilight we
have a five-minute long fight with
a dragon, and this was minutely
prevised, so we knew exactly
what elements we needed for that
sequence,” he says. “And it’s also
very important that you previs
with the same software that you
use later, so that the person who
then does the animation can actually
open that file and use that as
a basis for everything that will be
done from there.”
This illustrates the growing
relationship between pre- and
postproduction, in which software
compatibility allows for the “swapping
out” of low-res previs with
final CG elements.
Ron Frankel, formerly of Pixel
Liberation Front, recently started
Proof, his own previs company.
Frankel emphasizes the use of previs
as not only a tool to show a
directors’ vision of a sequence, but
the analytic view of the whole set
that allows planning for camera
placement and working out all the
technical details of a scene. “Previs
is a tool with which we can help
a production plan the execution
of a sequence with a remarkable
degree of accuracy,” he says.
In this way previs directly
affects grips, gaffers, and set
designers and dressers, who have
a new tool by which to predict the
needs of specific jobs. On Minority
Report, a film Frankel prevised
while still at Pixel Liberation, he
saw many benefits of previs for
below-the-liners.
“We had a complex shot where
an overhead camera tracks over
various apartments, showing people
inside the rooms,” remembers
Frankel. “When Spielberg initially
thought of the shot it was something
that concerned everybody
because they thought it was going
to be ridiculously expensive, that
would need some sort of custombuilt
motion-control system. But
the key grip approached and said
that he thought there was a way
to do it with the Technocrane. We
worked with him and his rigging
guy to come up with the plan of
how to rig it, and we determined
where the supports would be for
the tracks. We rendered this out
and gave it to the grips on a piece
of videotape, and they went up on
the stage a couple days before the
shoot and started to rehearse the
move. When it came time to film
it, they got it in three takes.”
Colin Greene of Pixel
Liberation Front points out that
previs artists can often contribute
to the storytelling of a film, creating
bits of story not in the script.
“Sometimes the script has been
vague. We did a sequence where
two characters are having a knife
fight, and the question came up,
where did they get the knives? We
worked with the director and prevised
a scene explaining it. This
is an example of how previs can
reveal what is needed for a scene
to make perfect sense.”
In Matrix Reloaded, Pixel did
the famous highway motorcycle
chase. The previs was so extraordinary
that the Wachowski brothers
brought the previs artists on
set to lay out the marks of where
the motorcycle and cameramotorcycle
should drive to weave
in between CG cars and trucks.
This is a great example of how previs
affects the actual shooting of a
film, rather than simply giving an
idea of how a scene should look.
Greene, one of the originators
of previs, is visionary about the
future of the process. He even sees
applications of previs as a sales
tool for films not yet green-lit—a
much more powerful tool than
old-school production sketches,
illustrations and storyboards.
“More and more we’re putting in
dialogue, music, sound effects,
and even character’s reactions,”
he says. Hence, a film of the film is created. One wonders if one day
such complete previs may reach
test audiences as a preproduction
gauge of potential success.
Another variety of previs is the
on-set type. “We sometimes call
that dur-vis,” jokes Greene. But
Michael Sanders of ILM, motion
capture engineer on Van Helsing,
Star Wars Episodes I and II, Peter
Pan and Pearl Harbor, is a master
of the on-set method. On AI, for
the Vegas-type city sequence, his
previs group built up a low res, low
texture model of the entire city,
and dropped it inside of a game
engine. Spielberg, by just pressing
a few buttons, could then navigate
the environment and block a
whole sequence.
“It was exactly like playing a
game,” says Sanders. “He could
pick lenses, do camera moves, and
make cuts. Then we would look
at what he did and go into a more
technical interface that we’d built,
and be able to check the moves
and see how technical they were
and whether they’d fit inside of the
environment—if they were going
to shoot it on a stage, we found
out how high the camera actually
started, where it was going, etc.”
When it came time to shoot,
the actors performed against blue
screens. But the previs team went
on set with Spielberg and provided
him a real-time composite of the
virtual environment with the liveaction
actors on the blue screen
set. It was accomplished by placing
images of the actors into the
3D digital set.
That seems to be the final goal
of previs; its ultimate future is as a
total planning tool that is as instantaneous
as playing a video game. By
using digital sets and actors with a
game engine, a director will be able
to pre-shoot his entire film, and by
pulling back to an analytical view,
technicians will be able to pre-plan
all their efforts, saving precious
time and labor.