Scientific Visualization: Something to RAVE About
John Quagliano, Dave Modl, Paul Argo, Laura Monroe, Steve Hodson,
Jeremy Margulies, Dave Hite, Bob Greene, and Karl-Heinz Winkler, High
Performance Computing Environments, CCN-8; and Robert Gurule,
Scientific Software Engineering, CCN-12
Los Alamos uses many types of advanced technologies to gain new
understandings of the physical world. Shown in Fig. 1, the RAVE
(Reconfigurable Advanced Visualization Environment) is designed for
scientists who need more sophisticated visual representations of
complex data acquired through computations and experiments. The RAVE is
part of the visualization facilities of the ASCI VIEWS program.
Designed specifically for Los Alamos, this version of the RAVE is the
only one of its exact kind and size in the world (for example,
NASA-Glenn has a RAVE, but it is smaller).
The RAVE was designed, built, and installed by Fakespace Systems Inc.,
the same company that built the Laboratory’s Powerwall and Immersive
Workbenches. Conceived in the spring of 1999 (just after the Powerwall
had been installed), the RAVE was completed in the fall of 2000 and was
demonstrated the week before Christmas 2000. Unlike the Powerwall, the
RAVE produces stereographic projections.
collaborates with various groups in other Laboratory divisions,
including Advanced Computing, Scientific Software Engineering, Plasma
Physics, Thermonuclear Applications, Computational Science Methods, and
Weapons Engineering. CCN-8 also maintains contact with groups at
Lawrence Livermore National Laboratory and Sandia National
Laboratories. Academic and industrial partners include the University
of Minnesota, University of New Mexico, SGI Inc., and Fakespace Systems
By sharing expertise with other organizations,
the Laboratory can easily leverage the newest computer hardware and
software technologies to best address the needs of scientists
performing simulations requiring supercomputer resources. Additionally,
half-hour-long demonstrations are routinely arranged for visiting VIPs
in both the RAVE and the Powerwall; each month we typically host four
to six groups of visitors.
The Los Alamos facility that houses the RAVE is quite large. The RAVE
boxes take up approximately one-half of the available 60-foot square
space. To help control the ambient lighting when the RAVE is used, our
room has special track lights that can be (1) fully programmed or (2)
Draperies form a 50-foot square around the center of the room and are
approximately 14 feet high, running from the ceiling to the floor, and
the floor itself has been carpeted. The projectors are low power and
thus are very quiet. All these added amenities provide a pleasant
workspace and make using the RAVE a comfortable experience.
Although much like the CAVE system sold by Pyramid Systems, the RAVE
has one principal difference: its pro-jection surfaces are not
restricted to one place as in the CAVE, thereby permitting many
display-panel orientations. (To download an MPEG movie that illustrates
various configurations, go to www.fakespacesystems.com/products1.htm
then click on the Workspace -> RAVE link). Each box has a footprint
of approximately 10 feet by 12 feet to support the 10-foot square
The Los Alamos RAVE includes two
floor panels for a true virtual reality experience. Possible
configurations include a four-wall panel and a one-floor panel “closed
box” arrangement, as well as two distinct “quarter box” (or “cove”)
displays that consist of two wall panels and one floor panel each. Our
primary configuration is a two-by-one setup resembling an “open-box” in
which there are two displays across the front and one on each side.
This configuration provides a viewing space of 20 by 10 feet across the
front and the floor and 10-foot square on each left- and right-side
panel. The current two-by-one configuration enables us to work in teams
and give demonstrations to many people without getting too crowded.
The RAVE units contain an Electrohome Marquee 9500LC projector coupled
with mirrors that produce an 18-foot light path to fill the 10-foot
square (Fig. 2).
These screens provided quite a challenge to get into the room during
construction. Each screen weighs approximately 700 pounds; a special
tilt-table with suction cup holders was built to move the glass into
The RAVE is fed video and user interfaces
from an SGI Origin 2000 computer containing ten Infinite Reality
Graphics boards (six are used by the RAVE) located in an adjacent
building. Signals are sent via fiber optics using Lightwave Video
Display Extention systems. Daryl Grunau of the Advanced Computing Group
has written a client-server PERL script that enables us to connect
directly to the Infinite Reality Graphics boards in both single- or
multi-pipe modes; the latter configuration is often required for
interactive visualization of very large data sets.
|Fig. 2. Dave Modl of CCN-8 tests the mirrors and projectors inside one of the RAVE boxes.
Visualization Software Applications
Following the installation of the RAVE, we dedicated several months to
develop, adapt, and expand many software packages for it. To create a
piece of software that could display on all surfaces, students at the
University of Illinois-Chicago used a popular tool known as CAVELib
(VRCO, Inc.) to create an immersive nature scene environment. The
CAVELib tool permits immersive and interactive virtual reality scenes
to be created for any non-flat multi-walled arena. CAVELib is an
application programmers interface that provides general support for
building virtual environments. It handles tasks such as drawing
stereoscopic views and organizing multiple processes.
EnSight® is a commercially available package (see www.ensight.com)
that can use multiple flat screens to display images. The Laboratory
has a site license for the Gold version of EnSight that runs in
parallel on the SGI IRIX operating system. This package was used to
project data sets collected from the Cerro Grande Fire (see this
issue’s inside front cover).
shows a multi-wall application of a red giant star’s simulated
structure. The data were computed at NCSA using the Piecewise Parabolic
Method package to compute the physics and the Hierarchical Volume
Rendering package from the University of Minnesota to create a stereo
movie with the correct viewing parameters for the RAVE’s two-by-one
display configuration. Paul Woodward and David Porter (University of
Minnesota) and Stephen Hodson (CCN-8) collaborated to produce a short
movie. This movie is displayed using a University of Minnesota moviola
player modified to playback stereo pair images on multiple displays.
Silicon Graphic’s Volumizer package provides real-time interaction with jet data. Figure 4
shows a single time step that can be displayed on all the screens in
the RAVE in stereo. Paul Argo (CCN-8) prepared the Volumizer
demonstration to view and manipulate the raw volume data from the
physics simulation. In this demonstration, the material’s transparency
can be changed interactively by using the mouse controls.
John Quagliano (CCN-8) has implemented and
expanded a tool known as the real-time ray tracer so that it can
generate photorealistic ray-traced geometric objects in stereo mode (Fig. 5).
This tool was originally developed by the University of Utah, one of
the Laboratory’s partners under the ASCI alliance. Quagliano has taken
this technology and coupled it with the RAVE. The ray tracer uses
massively parallel resources to compute a display image’s subsections,
which are subsequently assembled together to produce the full image. We
have used as many as 64 of the 128 processors on the Nirvana
visualization computer at the Laboratory to generate this particular
|Fig. 3. A volume rendering of a simulated red giant star.
We are exploring other options to connect the RAVE to other computer systems and expand its capabilities:
- Use a cluster of six Intel-based computers with 3Dlab’s Wildcat graphics cards to drive each of the six displays in the RAVE.
- Incorporate a position tracker system to track user’s movements in the RAVE.
- Add a surround-sound system to further enhance the immersive capability of the RAVE.
also are working to adapt other software application packages to the
immersive RAVE facility, such as CCS-1’s TRex high-performance parallel
volume visualization tool (see www.acl.lanl.gov/viz/pr-trex) and CCS-1’s and Kitware.com’s
parallelized vtk Visualization toolkit. We expect the vtk toolkit to
integrate smoothly with the CAVELib resources. Finally, we are
preparing for the eventual transition to the new Strategic Computing
Complex, which will house the new Laboratory supercomputer.
Scientific data have become more complex and data set sizes are getting
larger. Display systems used to visualize these data must try to keep
pace so that scientists can understand what is being computed. The
Fakespace RAVE display system, coupled with parallel software capable
of interactive and immersive stereo renderings, can handle these
growing visualization needs.
CCN-8 welcomes all inquiries concerning the RAVE. Karl-Heinz Winkler is
the CCN-8 Group Leader and Laura Monroe is the Scientific Visualization
Team Leader. We are available to discuss how this unique facility,
coupled with the expertise of our visualization team, can assist in
your scientific endeavors.
Using SGI’s Volumizer, we created this gray-scale visualization of data
shown in the background image found on this issue’s front cover.
||Fig. 5. The real-time ray tracer, when coupled with the RAVE, can produce photorealistic ray-traced geometric objects in stereo mode.