figure 2. in the natural world, focus distance (the distance to which the eyes must focus to
make an image sharp) and vergence distance (the distance at which the eyes’ lines of sight
converge on an object) are the same. however, most stereoscopic 3D displays require viewers to point their eyes at simulated distances while still focusing on the display’s actual
fixed distance. This incongruity can cause headaches and even nausea.
only will eliminate the need to wear
special glasses, but also will have the
ability to track head movement to render motion parallax accurately. And he
predicts the proliferation of more powerful content-creation technologies,
such as movie-production systems that
can render a scene from different viewpoints without reshooting it, and an
overall better understanding of vision
fatigue related to focus and depth cues.
With these and other technological advances, 3D viewing experiences will be
greatly improved, whether they occur
on big screens or small ones.
world. Banks is studying how the visual
system can tolerate such slow updates
and how viewers perceive such signals
to be smooth and convincing.
“For these studies, it would be use-
ful to have faster display technology
than we currently have,” Banks says.
“With such technology, we would be
able to better understand the conse-
quences of using different temporal
protocols in the presentation of stereo-
In a related project, Banks is study-
ing how blur affects the perception of
distance and size. Conventional opti-
cal devices, such as eyes and cameras,
can be focused only on one distance
at a time, which makes objects blurry
when they are farther from or nearer to
the focus distance. Banks is conduct-
ing studies to determine the relation-
ship between depth-of-field blur and
other depth cues, but also to under-
stand how changes in that relationship
affect human perception. The results
of such investigations could influence
the design of content for stereoscopic
3D cinema and television.
Akeley, K., Watt, S.J., Girshick, A.R.,
and Banks, M.S.
A stereo display prototype with multiple
focal distances. ACM Transactions on
Graphics 23, 3, August 2004.
Hoffman, D.M., Girshick, A.R., Akeley, K.,
and Banks, M.S.
Vergence-accommodation conflicts hinder
visual performance and cause visual fatigue.
Journal of Vision 8, 3, March 28, 2008.
Love, G.D., Hoffman, D.M., Hands, P.J. W.,
Gao, J., Kirby, A.K., and Banks, M.S.
high-speed switchable lens enables the
development of a volumetric stereoscopic
display. Optics Express 17, 18, August 2009.
3D Movie Making: Stereoscopic Digital
Cinema from Script to Screen. Focal Press,
Burlington, MA, 2009.
Watt, S.J., Akeley, K., Ernst, M.O.,
and Banks, M.S.
Focus cues affect perceived depth. Journal
of Vision 5, 10, December 15, 2005.
based in los angeles, Kirk L. Kroeker is a freelance
editor and writer specializing in science and technology.
© 2010 aCM 0001-0782/10/0800 $10.00
Automated Debugger for Parallel Programs
purdue university researchers,
collaborating with high-performance computing experts
at Lawrence Livermore national
Laboratory, have created an
automated debugging program
for the simulations used to
certify nuclear weapons.
called Automaded (for
automata-based debugging for
dissimilar parallel tasks), the
program finds errors in com-
puter code for complex parallel
International treaties forbid
the detonation of nuclear
test weapons, so certification
is performed with complex
simulations. these simulations
can last several weeks, and it
is common for an error in the
simulation code to not become
evident until long after it occurs,
which makes it difficult and
inefficient to locate the bug.
the primary developers of the
program are Lawrence Livermore
scientist greg Bronevetsky
and purdue doctoral student
Ignacio Laguna, and the paper,
debugging for dissimilar parallel
tasks,” was presented at the 40th
Annual Ieee/IFIp International
conference on dependable
systems and networks in chicago.