Doi: 10.1145/2398356.2398378
technical Perspective
Visualization, understanding,
and Design
By Doug DeCarlo and Matthew Stone
PhotoGRAPhs CAPtuRe the moment;
paintings convey perception, impression, and feeling; illustrations tell stories. Computer graphics aims to enrich all these artistic practices through
technology. The following paper is a
watershed in depiction, creating imagery that gets ideas across. Mitra et
al. describe an interactive system that
analyzes the operation of mechanical
devices and explains them visually to
users. Their compelling results showcase an innovative synthesis of newly
mature techniques for robust analysis
of 3D geometry and for domain-specif-ic information design.
Like many watershed papers in
computer graphics, this paper takes
its cues from the work of a master artist—in this case, RISD Professor and
MacArthur Fellow David Macaulay.
While Macaulay may be best known
for the engaging and richly informative visual storytelling of his architectural history books Cathedral and
Castle, the authors here base their
system on his book The Way Things
Work. It is a fascinating compendium
of explorations of everyday artifacts,
like the lock on your front door, illustrated through lucid visual explanations that communicate a deep
understanding. Such pictures are the
authors’ inspiration.
They get their understanding of
the world through geometry. They do
not simulate physics directly. They
use symmetries to infer how compo-
nents might move; they use correspon-
dences to recognize components that
can drive one another. The geomet-
ric computations allow approximate
matches, by exploiting the robust sta-
tistical principle that reliable symme-
tries and correspondences leave lots
of evidence. So a first step searches for
candidate matches, and a second step
tabulates the results to find consistent
patterns. Such techniques have a long
history, but recent bridges to comput-
er graphics have had an enormous in-
fluence on the practical analysis of 3D
shape, as you see here.
the following
paper is a watershed
in depiction,
creating imagery
that gets
ideas across.
analysis of exemplary hand-made
work, from artists’ reflection on their
practice, from psychological theories
of how people understand these visualizations, and from the researchers’
own experimentation with the possibilities of technology.
Realizing these design principles
involves a judicious choice of visual
techniques. Non-photorealism in
computer graphics offers diverse
ways to stylize appearances and guide
the viewer’s attention. Examples
include modulations of detail and
weight in rendering objects, the use
of cutting and transparency to depict
objects in multiple layers, and even
selective choices about which elements to render at all. The use here of
simple line drawings, with arrows for
annotation, and a constrained set of
highlighted parts and exploded views,
is a choice that reliably leads to clear
and uncluttered imagery. To create
accessible imagery with more richly
varying rendering techniques, or with
visualizations of additional information (forces, for example), it might be
necessary to develop much more nuanced design principles. The pictures
here, however, are clearly a success.
It is never easy to endow computers
with a deep and interesting understanding that they can share with their users.
But that does not mean we should regard inference as hopeless or design
as magic. As this work shows, general
tools and methodologies are making it easier and easier for systems to
communicate the understanding they
have through clear and compelling
visualizations. The results here thus
take on particular significance as a
benchmark in visual explanation, and
a model for future systems.
Doug DeCarlo ( decarlo@cs.rutgers.edu) and Matthew
Stone ( mdstone@cs.rutgers.edu) are associate professors
in the department of Computer science and Center for
Cognitive science at Rutgers university, Piscataway nj.
deCarlo is currently on leave at Google, Inc.
© 2013 aCM 0001-0782/13/01