How the Cool Tools Devised by Blue Sky Studios Created Twice the Toon in Half the Time
Global warming has hit ‘toonland — during Fox’s Blue Sky Studios’
feature Ice Age: The Meltdown, the prehistoric
characters spend most of the film escaping from an oncoming flood.
That's presented its own challenge for the filmmakers, because
animating water is one of the trickiest tasks in CG.
feature Ice Age: The Meltdown, the prehistoric
characters spend most of the film escaping from an oncoming flood.
That's presented its own challenge for the filmmakers, because
animating water is one of the trickiest tasks in CG.
The crew of artists creating the film had to hit the ground running,
too. “We had to do the movie in half the time,” says director Carlos
Saldanha, who quickly warmed to the task. “It wasn’t an easy decision,
but when the studio asked if we wanted to face the challenge, everybody
said, ‘Let’s do it.’ The team was motivated — they loved the story and
they loved the characters.”
too. “We had to do the movie in half the time,” says director Carlos
Saldanha, who quickly warmed to the task. “It wasn’t an easy decision,
but when the studio asked if we wanted to face the challenge, everybody
said, ‘Let’s do it.’ The team was motivated — they loved the story and
they loved the characters.”
Saldanha, who had co-directed Ice Age and
Robots, the studio’s first two features, and
directed “Gone Nutty,” an Oscar-nominated short, was ready. “The good
news was that we had a solid script up on reels,” Saldanha says. “Every
sequence had to work. We pounded on the story every day. We didn’t have
room for mistakes.” At the end, the script was so tight that there were
no outtakes for the DVD. “Sequences went from the edit room to the
animators. We didn’t have time to rethink the dialog.”
Robots, the studio’s first two features, and
directed “Gone Nutty,” an Oscar-nominated short, was ready. “The good
news was that we had a solid script up on reels,” Saldanha says. “Every
sequence had to work. We pounded on the story every day. We didn’t have
room for mistakes.” At the end, the script was so tight that there were
no outtakes for the DVD. “Sequences went from the edit room to the
animators. We didn’t have time to rethink the dialog.”
The team streamlined all the other areas of the production as well,
from modeling through animation and rendering. Last year's
Robots was a testing ground for new technology that
made Ice Age: The Meltdown possible, but when the
studio turned up the heat on the schedule, the crew devised new
technology and techniques especially for this film. “We had an
adrenalin rush for a year,” says Saldanha.
from modeling through animation and rendering. Last year's
Robots was a testing ground for new technology that
made Ice Age: The Meltdown possible, but when the
studio turned up the heat on the schedule, the crew devised new
technology and techniques especially for this film. “We had an
adrenalin rush for a year,” says Saldanha.
Beauty on the Surface
Having familiar characters to work with saved the crew some time in
character development: All the lead characters from the original
Ice Age returned: Manny the mammoth (Ray Romano),
Sid the sloth (John Leguizamo), Diego the lion (Denis Leary), and Scrat
the acorn-loving squirrel (Chris Wedge). However, the modelers created
around 35 new characters with multiple variations for migrating herds
and 40 environmental sets that included more than 150 different types
of trees. In addition, the modelers had to convert the original
characters from NURBS models into subdivision surfaces.
character development: All the lead characters from the original
Ice Age returned: Manny the mammoth (Ray Romano),
Sid the sloth (John Leguizamo), Diego the lion (Denis Leary), and Scrat
the acorn-loving squirrel (Chris Wedge). However, the modelers created
around 35 new characters with multiple variations for migrating herds
and 40 environmental sets that included more than 150 different types
of trees. In addition, the modelers had to convert the original
characters from NURBS models into subdivision surfaces.
Blue Sky bases its modeling, rigging, and animation system on
Autodesk’s Maya. For rendering, though, the studio relies on its own
CGI Studio, sophisticated ray tracing software that incorporates an
object-oriented graphics programming language. The renderer and other
software tools have been in development since the studio’s founding in
1987.
Autodesk’s Maya. For rendering, though, the studio relies on its own
CGI Studio, sophisticated ray tracing software that incorporates an
object-oriented graphics programming language. The renderer and other
software tools have been in development since the studio’s founding in
1987.
“We’ve developed a unique workflow,” says technical lead Eric Maurer.
“The founders, and [CTO] Carl Ludwig in particular, have developed
robust solutions that are physically accurate, look correct, and work
correctly for the user with very little intervention.”
“The founders, and [CTO] Carl Ludwig in particular, have developed
robust solutions that are physically accurate, look correct, and work
correctly for the user with very little intervention.”
For example, Blue Sky’s ray tracer can bounce rays off Bezier patches
rather than, as with many ray tracers, only polygonal faces. “We have
our own subdivision representation — hierarchical subdivisions that
are all parametric patches, continuous curves,” explains Ludwig. Thus,
rather than create characters in NURBS and then convert the patches
into smooth surfaces made with ever-tinier polygons, the modelers now
work with subdivision surfaces.
rather than, as with many ray tracers, only polygonal faces. “We have
our own subdivision representation — hierarchical subdivisions that
are all parametric patches, continuous curves,” explains Ludwig. Thus,
rather than create characters in NURBS and then convert the patches
into smooth surfaces made with ever-tinier polygons, the modelers now
work with subdivision surfaces.
“The subdivision surfaces gave us a lot of advantages,” says character
rigger Steve Unterfrantz. “We no longer have to worry about seams,
pinching, and tearing where the NURBS surfaces touch each other. It was
a challenge for the animators to create the same performances for the
[returning] characters using new models and rigs, but there were so
many savings in other ways, it was the logical thing to do.”
rigger Steve Unterfrantz. “We no longer have to worry about seams,
pinching, and tearing where the NURBS surfaces touch each other. It was
a challenge for the animators to create the same performances for the
[returning] characters using new models and rigs, but there were so
many savings in other ways, it was the logical thing to do.”
Also, although dealing with curving patch intersections is a more
complex problem for a ray tracer to solve than bouncing rays off
thousands of flat surfaces, rendering the patch-based surfaces takes
less memory, especially when a ray tracer has to calculate secondary
reflections and refractions.
complex problem for a ray tracer to solve than bouncing rays off
thousands of flat surfaces, rendering the patch-based surfaces takes
less memory, especially when a ray tracer has to calculate secondary
reflections and refractions.
Moving Right Along
To meet the accelerated schedule, the modeling, rigging and animation
departments devised methods to speed their workflow. For new lead
characters, modelers used templates from a Polhemus scanner. To create
multitudes of characters, riggers created variations from generic
models. Character riggers also developed modular rigs and Mel scripts
that assembled the modules into characters. The modular approach not
only sped the rigging process, it meant that animators could more
easily move from character to character.
departments devised methods to speed their workflow. For new lead
characters, modelers used templates from a Polhemus scanner. To create
multitudes of characters, riggers created variations from generic
models. Character riggers also developed modular rigs and Mel scripts
that assembled the modules into characters. The modular approach not
only sped the rigging process, it meant that animators could more
easily move from character to character.
Sixty-five animators worked on Ice Age: The Meltdown
— nearly double the number on Ice Age — and only
eight of them had animated the original characters. “Four or five of us
set up libraries for the new animators that showed how a character
moves and why it moves that way, to make sure the other 55 or 60 people
always stayed on model,” says Aaron Hartline, an animation lead.
— nearly double the number on Ice Age — and only
eight of them had animated the original characters. “Four or five of us
set up libraries for the new animators that showed how a character
moves and why it moves that way, to make sure the other 55 or 60 people
always stayed on model,” says Aaron Hartline, an animation lead.
Animators worked on a shot-by-shot basis, creating performances for all
the characters in a shot, rather than following individual characters.
And they worked fast. “We were so focused, so
direct, it was almost like we stuck with the first gut instinct that
came out,” says Saldanha. “I’d say, ‘OK, this is the scene and this is
what we need. Go, go, go, go. We didn’t overthink or second-guess. I
think that rawness of the idea is there and that’s what I love the
most.”
the characters in a shot, rather than following individual characters.
And they worked fast. “We were so focused, so
direct, it was almost like we stuck with the first gut instinct that
came out,” says Saldanha. “I’d say, ‘OK, this is the scene and this is
what we need. Go, go, go, go. We didn’t overthink or second-guess. I
think that rawness of the idea is there and that’s what I love the
most.”
Hartline, who led the animation for Scrat, agrees. “We had to trust our
first approach,” he says. “We’d just tweak that raw performance to get
the best out of it. There was something good about that, something
fresh.”
first approach,” he says. “We’d just tweak that raw performance to get
the best out of it. There was something good about that, something
fresh.”
Shades of Fur
Nearly all the characters in are furry or feathered. With Blue Sky’s
fur system, groomers set parameters for guide hairs that control the
hair’s style; the system then procedurally generates millions of hairs
on the creatures’ coats using these parameters. It’s a typical
fur-grooming system. However, three things about the fur system stand
out: procedural motion is rigged into the guide hairs, no texture maps
are used, and a voxel-based system renders the fur.
fur system, groomers set parameters for guide hairs that control the
hair’s style; the system then procedurally generates millions of hairs
on the creatures’ coats using these parameters. It’s a typical
fur-grooming system. However, three things about the fur system stand
out: procedural motion is rigged into the guide hairs, no texture maps
are used, and a voxel-based system renders the fur.
Rather than using a simulation engine, a system called
“follow-through,” which was developed by Adam Burr, calculates the
fur’s movement by predicting a result based on previous motion.
Animators control stiffness, the amount of follow-through, and
something Maurer calls “settle time.”
“follow-through,” which was developed by Adam Burr, calculates the
fur’s movement by predicting a result based on previous motion.
Animators control stiffness, the amount of follow-through, and
something Maurer calls “settle time.”
“We also use gravity and wind vectors,” Maurer says. “But the engine
isn’t solving the problem from a dynamics point of view. It’s solving
it almost from a probability point of view. You need a team of people
to finesse a simulation engine. This tool is automatic.”
isn’t solving the problem from a dynamics point of view. It’s solving
it almost from a probability point of view. You need a team of people
to finesse a simulation engine. This tool is automatic.”
To color the hair, technical directors used procedural shaders rather
than painted texture maps, an approach that was tried successfully on
Robots and implemented throughout Ice Age:
The Meltdown. “You could probably count on two hands the
total number of texture maps in the whole movie,” says Brian Hill,
materials technical director (TD). The procedural shading system uses a
Maya interface over a custom-node based network and compiles the
shaders in Maya. Plug-in splines describe areas for color, noise
creates textures, and TDs used nodes to create such other material
properties as specular highlights and roughness.
than painted texture maps, an approach that was tried successfully on
Robots and implemented throughout Ice Age:
The Meltdown. “You could probably count on two hands the
total number of texture maps in the whole movie,” says Brian Hill,
materials technical director (TD). The procedural shading system uses a
Maya interface over a custom-node based network and compiles the
shaders in Maya. Plug-in splines describe areas for color, noise
creates textures, and TDs used nodes to create such other material
properties as specular highlights and roughness.
“We avoid maps unless we need them,” says Ludwig. “They take up memory,
they have to be repainted, and they’re more difficult to work with.”
they have to be repainted, and they’re more difficult to work with.”
Developing a network of nodes can be time-consuming, but unlike texture
maps, the procedural shaders can move from character to character. “I
created a procedural material for a condor’s foot — layer after layer
of procedural elements that gave the nasty-looking claw foot fine,
cellular detail,” says Hill. “Then, I used that same network for the
other foot, for the condor chicks and with a little variation for all
the other birds. It takes more time at the beginning, but it’s much
more modular than maps.”
maps, the procedural shaders can move from character to character. “I
created a procedural material for a condor’s foot — layer after layer
of procedural elements that gave the nasty-looking claw foot fine,
cellular detail,” says Hill. “Then, I used that same network for the
other foot, for the condor chicks and with a little variation for all
the other birds. It takes more time at the beginning, but it’s much
more modular than maps.”
To render the fur, in keeping with the studio’s philosophy, a new
volumetrically-based fur system accomplished two goals: the fur looks
three-dimensional and the lighters’ job became easier. “The lighters
might use separate lights for the characters to help them stand out
from the background, but they didn’t need to do any special grooming or
use separate lights for the fur,” says Ludwig. “The volume-based
lighting model was integrated within the lighting system, so it acts
properly with lights in the environment and with shadows and global
illumination. When you get something that works right all the time, you
need to do less special stuff to make it look right.”
volumetrically-based fur system accomplished two goals: the fur looks
three-dimensional and the lighters’ job became easier. “The lighters
might use separate lights for the characters to help them stand out
from the background, but they didn’t need to do any special grooming or
use separate lights for the fur,” says Ludwig. “The volume-based
lighting model was integrated within the lighting system, so it acts
properly with lights in the environment and with shadows and global
illumination. When you get something that works right all the time, you
need to do less special stuff to make it look right.”
Maurer provides another time-saving example, this one from the
materials side: “Most 3D packages have specular and diffuse sliders,”
he says, “but in the real world, specular and diffuse have an inverse
relationship. So our materials usually need only specular. Diffuse is
calculated from specular.”
materials side: “Most 3D packages have specular and diffuse sliders,”
he says, “but in the real world, specular and diffuse have an inverse
relationship. So our materials usually need only specular. Diffuse is
calculated from specular.”
Water World
Melting ice creates water, of course, which meant Blue Sky had to
create gallons of CG water, from a water park showcased at the
beginning of the film to a threatening flood. “We know water is hard to
animate and control in CG and expensive to render” says Rob Cavaleri,
effects supervisor. “Our challenge was to blend physical reality with a
directable caricatured style for our cartoon world. We managed to pull
it off in a year.”
create gallons of CG water, from a water park showcased at the
beginning of the film to a threatening flood. “We know water is hard to
animate and control in CG and expensive to render” says Rob Cavaleri,
effects supervisor. “Our challenge was to blend physical reality with a
directable caricatured style for our cartoon world. We managed to pull
it off in a year.”
They did this with a combination of deformable geometry that emitted
particles to create splashes, with procedurally animated surfaces based
on physical models of waveforms, and with simulations created with Next
Limit Real Flow software. Special rigs attached to characters emitted
bubbles as characters swam through the water. To create froth, during
rendering a system written in the CGI Studio language automatically
generated particles around characters and objects such as rocks, and
created a mesh around the particles to have a renderable surface. “We
could tell it how long the froth lived and how swiftly it moved,” says
Cavaleri. “The animation was all procedural; the particles moved along
wave surfaces automatically. We would never have managed without these
clever techniques.”
particles to create splashes, with procedurally animated surfaces based
on physical models of waveforms, and with simulations created with Next
Limit Real Flow software. Special rigs attached to characters emitted
bubbles as characters swam through the water. To create froth, during
rendering a system written in the CGI Studio language automatically
generated particles around characters and objects such as rocks, and
created a mesh around the particles to have a renderable surface. “We
could tell it how long the froth lived and how swiftly it moved,” says
Cavaleri. “The animation was all procedural; the particles moved along
wave surfaces automatically. We would never have managed without these
clever techniques.”
Ready, Set, Go
In most scenes, the water was contained within sets that ranged from
icebergs to grasslands to forests. Few matte paintings were used —
modelers created most of the sets. For Ice Age, the
modeling department built the sets on a per-shot basis from the camera
view as described in the layout. Despite the short timeframe, for
Ice Age: The Meltdown, modelers created complete
environments that had some details even in areas where the camera
wasn’t expected to go. “When we were working on the first Ice
Age, sometimes the director wanted to move the camera where
there was no set,” says Shaun Cusick, co-head of modeling. “There were
lots of charge-backs to other departments and it slowed things down. So
for this one we tried to build the set as an entire environment.”
icebergs to grasslands to forests. Few matte paintings were used —
modelers created most of the sets. For Ice Age, the
modeling department built the sets on a per-shot basis from the camera
view as described in the layout. Despite the short timeframe, for
Ice Age: The Meltdown, modelers created complete
environments that had some details even in areas where the camera
wasn’t expected to go. “When we were working on the first Ice
Age, sometimes the director wanted to move the camera where
there was no set,” says Shaun Cusick, co-head of modeling. “There were
lots of charge-backs to other departments and it slowed things down. So
for this one we tried to build the set as an entire environment.”
The voxel-based method used for fur also rendered grass, and procedural
shaders also textured the environments. Thus, rendering the
environments became an interesting technical challenge that was solved
by staging the geometry from complex in the foreground to less complex
in the distance. It was only one of many challenges as the team raced
to the finish line.
shaders also textured the environments. Thus, rendering the
environments became an interesting technical challenge that was solved
by staging the geometry from complex in the foreground to less complex
in the distance. It was only one of many challenges as the team raced
to the finish line.
“We were on our toes to the end,” says Matt Simmons, animation
technical lead, who fed shots from the animators into the rendering
system. “We were going 150 percent the whole time. There was no
ramp-down. But luckily, everyone was great and it was fun. I already
miss working with Carlos.”
technical lead, who fed shots from the animators into the rendering
system. “We were going 150 percent the whole time. There was no
ramp-down. But luckily, everyone was great and it was fun. I already
miss working with Carlos.”
And what about Saldahna, who has directed three features and a short
film in little more than five years? “I think when everything is done,
I’ll be standing alone in a room saying, ‘Hello — anyone? What shall I
do?’ It’s a miracle. It’s one of those amazing things. Those guys …
it’s extremely emotional for me."
film in little more than five years? “I think when everything is done,
I’ll be standing alone in a room saying, ‘Hello — anyone? What shall I
do?’ It’s a miracle. It’s one of those amazing things. Those guys …
it’s extremely emotional for me."
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