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3D Computer Animation
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3D Animation |
In most 3D computer animation systems, an animator
creates a simplified representation of a character's anatomy,
analogous to a skeleton or stick figure. The position of each
segment of the skeletal model is defined by animation variables, or
Avars. In human and animal characters, many parts of the skeletal
model correspond to actual bones, but skeletal animation is also
used to animate other things, such as facial features (though other
methods for facial animation exist). The character "Woody" in Toy
Story, for example, uses 700 Avars, including 100 Avars in the face.
The computer does not usually render the skeletal model directly (it
is invisible), but uses the skeletal model to compute the exact
position and orientation of the character, which is eventually
rendered into an image. Thus by changing the values of Avars over
time, the animator creates motion by making the character move from
frame to frame.
There are several methods for generating the Avar values to obtain
realistic motion. Traditionally, animators manipulate the Avars
directly. Rather than set Avars for every frame, they usually set
Avars at strategic points (frames) in time and let the computer
interpolate or 'tween' between them, a process called keyframing.
Keyframing puts control in the hands of the animator, and has roots
in hand-drawn traditional animation.
In contrast, a newer method called motion capture makes use of live
action. When computer animation is driven by motion capture, a real
performer acts out the scene as if they were the character to be
animated. His or her motion is recorded to a computer using video
cameras and markers, and that performance is then applied to the
animated character.
Each method has its advantages, and as of 2007, games and films are
using either or both of these methods in productions. Keyframe
animation can produce motions that would be difficult or impossible
to act out, while motion capture can reproduce the subtleties of a
particular actor. For example, in the 2006 film Pirates of the
Caribbean: Dead Man's Chest, actor Bill Nighy provided the
performance for the character Davy Jones. Even though Nighy himself
doesn't appear in the film, the movie benefited from his performance
by recording the nuances of his body language, posture, facial
expressions, etc. Thus motion capture is appropriate in situations
where believable, realistic behavior and action is required, but the
types of characters required exceed what can be done through
conventional costuming.
3D computer animation combines 3D models of objects and programmed
or hand "keyframed" movement. Models are constructed out of
geometrical vertices, faces, and edges in a 3D coordinate system.
Objects are sculpted much like real clay or plaster, working from
general forms to specific details with various sculpting tools. A
bone/joint animation system is set up to deform the CGI model (e.g.,
to make a humanoid model walk). In a process called rigging, the
virtual marionette is given various controllers and handles for
controlling movement. Animation data can be created using motion
capture, or keyframing by a human animator, or a combination of the
two.
3D models rigged for animation may contain thousands of control
points - for example, the character "Woody" in Pixar's movie Toy
Story, uses 700 specialized animation controllers. Rhythm and Hues
Studios labored for two years to create Aslan in the movie The
Chronicles of Narnia: The Lion, the Witch and the Wardrobe which had
about 1851 controllers, 742 in just the face alone. In the 2004 film
The Day After Tomorrow, designers had to design forces of extreme
weather with the help of video references and accurate
meteorological facts. For the 2005 remake of King Kong, actor Andy
Serkis was used to help designers pinpoint the gorilla's prime
location in the shots and used his expressions to model "human"
characteristics onto the creature. Serkis had earlier provided the
voice and performance for Gollum in J. R. R. Tolkien's The Lord of
the Rings trilogy.
Computer animation can be created with a computer and animation
software. Some impressive animation can be achieved even with basic
programs; however, the rendering can take a lot of time on an
ordinary home computer. Because of this, video game animators tend
to use low resolution, low polygon count renders, such that the
graphics can be rendered in real time on a home computer.
Photorealistic animation would be impractical in this context.
Professional animators of movies, television, and video sequences on
computer games make photorealistic animation with high detail. This
level of quality for movie animation would take tens to hundreds of
years to create on a home computer. Many powerful workstation
computers are used instead. Graphics workstation computers use two
to four processors, and thus are a lot more powerful than a home
computer, and are specialized for rendering. A large number of
workstations (known as a render farm) are networked together to
effectively act as a giant computer. The result is a
computer-animated movie that can be completed in about one to five
years (this process is not comprised solely of rendering, however).
A workstation typically costs $2,000 to $16,000, with the more
expensive stations being able to render much faster, due to the more
technologically advanced hardware that they contain. Pixar's
Renderman is rendering software which is widely used as the movie
animation industry standard, in competition with Mental Ray. It can
be bought at the official Pixar website for about $3,500. It will
work on Linux, Mac OS X, and Microsoft Windows based graphics
workstations along with an animation program such as Maya and
Softimage XSI. Professionals also use digital movie cameras, motion
capture or performance capture, bluescreens, film editing software,
props, and other tools for movie animation.
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For many years, I have lived
uncomfortably with the belief that most planning and architectural design
suffers for lack of real and basic purpose. The ultimate purpose, it seems
to me, must be the improvement of mankind.
James Rouse
I am but an architectural composer.
Alexander Jackson Davis
I hope that America as a whole, and especially its architects, will become
more seriously involved in producing a new architectural culture that would
bring the nation to the apex - where it has stood before - and lead the
world.
Tadao Ando
I look upon myself as a musical bricklayer with architectural aspirations.
Robert Mayer
I'd say that my profession ends where architectural thinking ends -
architectural thinking in terms of thinking about programs and
organizational structure. These abstractions play a role in many other
disciplines, and those disciplines are now defining their 'architectures' as
well.
Rem Koolhaas
I'm not an architectural composer.
Harrison Birtwistle
It fills one with a sense of architectural possibility.
Paul Goldberger
It was always my intention that The Frieze should be housed in a room which
would provide a suitable architectural frame for it.
Edvard Munch
Profit and bottom line, the contemporary mantra, eliminates the very source
of architectural expression.
Arthur Erickson
Supply and demand regulate architectural form.
Adolf Loos
The center of Western culture is Greece, and we have never lost our ties
with the architectural concepts of that ancient civilization.
Stephen Gardiner
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