American Cinematographer - February 1999 - 110

the billboard itself. For

example, that
gives us a full 360-degree move around a
chariot in 3-D; when that's plotted out,

Notes The Prince
of Egypt's scene¬

planning
supervisor, Dave
Morehead, "In
the chariot race,
we wanted the
2-D horses to
seem as if they
were

3-D

pulling the
chariot,

so

the
2-D animator

would start off

drawing

by
rough

a
horse and

a

rough chariot.
Then we'd format
those
so

drawings

that the 3-D

animators could
work with them
in that
environment."

23--DD

the character animator

adds Morehead. "Then we'll take their

drawings and
computer."

scan

those back into the

Animators can also employ this
technique to create the illusion of grow¬
ing size as a character rides from the
distance into close-up. "Most of the
animation is not really done in perspec¬
tive, per se," Morehead says. "For a
scene of the chariot flying down the
street, the animator might be looking at
the chariot from the same perspective
the whole time. We can use the plot
to extract out all the translation

component has to offer. But we don't

camera

movement, rather than drawing the
acter small when he's far away and

worlds has been kind of difficult. 3-D

actually composite the elements in Expo¬
sure
instead, it acts as the choreogra¬
phy tool, sending instructions back to the
individual packages as to where to put

char¬
large
when he gets closer. That way, the char¬
iot pretty much stays the same size and
the animators animate

primary responsibility to
integration between all of the
and 3-D elements. Up until now, the
choreography of those 3-D and 2-D
our

handle the

-

packages like Alias and Softimage are

the

great for working in 3-D environments,
but they don't really lend themselves to

object in the scene so they all lock
together. Then the compositing of all the

image. It's a significant advantage - not
just in look, but cost as well - because

the flat 2-D world. What we wanted

elements is done in Animo."

we

a

tool that would combine the

was

cameras

With

strengths

and how to

move

each

Exposure, the virtual camera

of both worlds, and allow us to conve¬

rotates around the 3-D chariots as it's

niently choreograph all of these 2-D and

also rotating at the same speed around
the "billboards," flat cutouts of the char¬
acters in the chariots over which the

elements in

Moses

one

"Now, if

interface.

we want

sitting in

a

to animate

chariot,

animate Moses and then

we can

Exposure
to bring that into [Cambridge Animation
Systems'] Animo - our 2-D animation
package - along with an Alias wire file
of the chariot. We then choreograph
use

artists animate.
can

"Through Exposure, we
assign behaviors to the billboards

that the characters

character to it, we'd have to re-draw the

character in

ual

sure, we

Animo does all of the 2-D work. Thanks

object to another object, which means
we can actually put a billboard
inside a chariot and parent it, so when
we move the chariot around, the bill¬
board goes with it. That way, the charac¬
that

sort of 'translator.' And it's not

distinct

just a one¬
ongoing
communication between the 3-D, 2-D
digital and paper worlds, which allows
us to pull in the best features that each
-

it's

an

different position every
object moved. But in Expo¬

a

have all the common 3-D prop¬
erties, like being able to 'parent' one

Exposure, the traditional animators
could get the 3-D elements from Alias
onto paper, and the Alias animators
could have all of the drawings in the shot
in the 3-D world. Exposure started off as
a choreography tool, but turned into a

time translation

on," Morehead

3-D elements first, and then animate the

time that 3-D

to

are

reveals. "Before, when we'd do all of the

them both and put a camera move
around them. That way, the two individ¬

packages are doing what they do
best-Alias deals with 3-D objects, and

February 1999

the chariot

can actually
animate that revolve to his character,"

and it's

108

sees

revolving completely and

ter doesn't have to be animated every

time the

camera

moves,

which is

a

advantage."

"Then,

lock

'plot camera' to
print out each frame of
the chariot on 11" by 17" paper, translat¬
ing the perspective of the 3-D object onto
we

the billboard to

a

a

constant-size

don't have to re-animate that charac¬

time the chariot moves."
powerful tool primarily
handles choreography of the 2-D and 3-D
elements, why the name Exposure,
which conjures images of a lighting tool?
"It does everything but the lighting,"
concedes Morehead. "We didn't actually
pick the name, the developers picked it.
To me, it doesn't matter what you call it,
except that people are always asking
me, 'Oh, now show me the Exposure
portion,' and I have to explain, 'Well, it
does choreography.'"
Although Exposure does not
affect the lighting of a 3-D scene, it has
enabled real-world background painters
ter every

But if this

to translate their 2-D work into

3-D, with

remarkable results. "After we've built

a

3-D set, we'll print a specific angle out,
which becomes a template that the back¬

ground painter physically paints using
oils," Morehead says. "Then we scan the
painting and project that image onto the
3-D geometry. The Exposure tool extends
the painting into the room and gives us
parallax on all the objects. Therefore,
what we got when we rendered the
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