American Cinematographer - April 2004 - 108

The ZeroG

trickery is required. "With Pooh, when
the puppets crossed behind set objects,

crane

and its encoded
movements

drive

the matte needed to be switched

the virtual set

built in

Par 64

cans

punched through
overhead grid
cloth to create
an

overall soft
ambiance.

Because the

set in front of the

crowd of

puppeteers

key
lighting, Logan

before

switching the matte off so the
in front of it.
Obviously, a character cannot be both

character will appear

lit the mice from
below to
emulate

pools of
streetlight that

behind and in front of the tree at the

time
hugging the tree, so to
speak. But for that show, everything

reflect off the CG

same

set's floor.
Below: The

real-time

composite while
they work and
sometimes

use

practical
such

as

props,
the stalk

of bamboo.

-

could be worked out around that limita¬

puppeteers are
a

character, and he waits
even with the tree

until the character is

could block

able to view

manu¬

ally," he explains. "Every object in the set
has an alpha channel and can be
controlled separately. For instance, a
character might start out behind a tree,
walk by the tree, and then move in front
of it. The set operator has the tree matte

Maya.

against blue- or greenscreen back¬
grounds, camera operator Kevin Burke
operated off a flatscreen monitor that
showed a composite of the characters
with a real-time matte and the Maya set.
Essentially, this means that he was
seeing the final image. As Logan points
out, "He could compose for the set as
well
see

the characters, because he could

as

where

they

were

in relationship to

The

growth of the Virtual Set
initiated by Entertainment
Design Workshop. Says Logan,
"Brainstorm's Paul Lacombe, originally of
E.D.W., developed the encoding system
and integrated software. Shadow
Projects bought the technology, and they
have further developed it into the unique
was

today."

Since it

was a

show aimed at

toddlers, The Book of Pooh

was an

easier bear to handle. Shot with

a

Philips
LDK2000 DigiBeta camera and a 15:1
Fujinon high-definition lens. Pooh's Maya
set was designed from shapes with low
polygon counts that required less
memory. "It was designed with an
aesthetic that

was more

like

a

pop-up

that everything was like a twodimensional surface," Logan details.
"Therefore, the system worked really
book,

the set."
Process

art form it is

so

well in real time. The output

of that

system is what aired on TV, occasionally
with

a

little roto

cleanup if certain shots

ically interact with it. In

a

interacts with

live character
a

virtual

or

object,

puppet
a

a

post-render
prob¬

situation like SKFM, it was never a

lem, because the mattes can be tweaked
in the post process.

The same liveswitching situation, however, was used
for the real-time rough comp."
For Mice, which was basically a
theatrical test, the Virtual Set Process
was taken to the next level. A consider¬

detailed and memory-hungry
Maya by
production designer Chris Renaud and
CG supervisor William "Jens" Scott, and
the puppets were shot with a Sony
ably

more

restaurant set was built in

HDW-F900 CineAlta and

needed it."
When

tion, usually by having a real object [in
the frame] if the puppets needed to phys¬

52mm

zoom

"Because

bit of

a

Canon 4.7-

lens.
of

the

calibration

process of syncing up the camera with
the computer, each lens change takes

about

a

half hour,"

Logan notes. "We

therefore needed to find

one

lens to

shoot the entire show." Whatever lens
to be used, it had to be mapped
exactly to ascertain its known optical
distortion at every focal length. The
distortion was written into the Maya set
via an algorithm in order to match the CG
background with the real foreground.

was

"The Canon HD lens is

a

great

piece of glass," he enthuses. "It has
excellent resolution all the way through
the field.

It doesn't breathe when

focused. It offered

everything we needed
really wide, almost cartoon look
that was still tight enough at the long

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104

April 2004

a
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