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NEW MACHINES TO VISUALIZE DATA: AN IMMERSIVE VIRTUAL REALITY TEST BED AT NOAA's PACIFIC MARINE ENVIRONMENTAL LABORATORY
February 1, 2002 — NOAA's Pacific
Marine Environmental Laboratory carries out interdisciplinary
scientific investigations in oceanography and atmospheric science to support
NOAA's mission. PMEL is utilizing new
interactive and immersive visualization tools which provide unprecedented
power to explore NOAA's data sets and to communicate new research findings.
As computational
power increases, and observation systems sample our Earth's environment
more densely in space and 
time,
NOAA's data sets have become increasingly large and more complex. Moreover,
model results are often generated at remote supercomputing centers, and
observational data are increasingly available in near-real time over high
bandwidth networks. Even animations of 2-D plots are not adequate to fully
reveal the complexity of these large data sets. Utilizing immersive virtual
environments, PMEL is playing a transforming role in understanding and
utilizing NOAA environmental data. Virtual reality allows the user to
view, navigate, and interact with multidimensional fields in 3-D stereographic
projections to provide unparalleled insights into processes that might
otherwise be impossible. Collaborative virtual environments (sometimes
referred to as tele-immersion) allow users to interact with the virtual
world and with other users in a shared environment.
Why 3-D? Early graphing tools allowed the user to simply plot variables in two dimensions (2-D). However, oceanographic and atmospheric data are inherently three-dimensional and are therefore best represented with the next generation of visual applications, as 3-D stereographic perspective plots.
Virtual Reality: Although a 3-D perspective plot clearly provides much useful information, the next step in the evolution of scientific visualization is to add motion parallax (perceiving an object's distance and size by the use of relative motion) and stereographic rendering, so that the difference in images that the right and left eye views gives the observer clues as to object distance and size. This advancement provides a powerful way to examine a surface or other three-dimensional object by viewing it "up close" with two eyes, from any angle, as if you were holding the object in your hands. With the "two eyes" provided by stereographic rendering, the scientist can clearly see which parts of the object lie in front of or behind other parts, and clearly distinguish up from down, left from right, and forward from backward. One no longer confuses small features as being further away simply because they are smaller. The realism of virtual reality enables the scientist and the lay person to understand complex ideas more easily. Immersive 3-D stereographic rendering is an easy way to more efficiently view and analyze large and complex oceanographic and atmospheric data. Scientists using virtual reality affirm this new technology discloses features of their data and model outputs that were undiscovered with standard visualization techniques. Scientists at NOAA's Pacific Marine Environmental Laboratory use the large-format ImmersaDesk (as well as desktop rendering) to view their data.
The ImmersaDesk is a large format (82.5" screen), projection-based virtual reality workdesk device that uses stereo glasses and head/hand tracking to offer a type of virtual reality that is considered "semi-immersive." That is, it successfully achieves the illusion of an immersive virtual environment without fully surrounding the user (the room-sized CAVE is a fully immersive virtual reality workspace device). Wearing special glasses, a user can look into the ImmersaDesk's large angled screen to "see, hear, and touch" a computer-generated 3-D image that allows the user to interact with physical oceanographic and meteorological data in three dimensions and in stereo. Both elevation and birds-eye-view are possible. A Silicon Graphics Onyx2 drives the animations on the ImmersaDesk, using several software packages (including Cave5D, Iris Explorer, VTK, and vGeo). The ImmersaDesk model R2, which has been acquired by PMEL, is a roadworthy (air cargo qualified) version of the ImmersaDesk, and is well-suited for large conference and meeting environments. Specifically, five or six viewers can comfortably arrange themselves around the screen and view an animation as the scientist explains the phenomenon and fields questions. Day-to-day use of stereo rendering is usually done on the desktop.
Desktop Visualization: PMEL scientists have found that desktop immersive 3-D stereo rendering, such as the Virtual Reality Modeling Language (VRML), is a relatively easy, Web-accessible way to more efficiently view and analyze oceanographic and atmospheric data. The expanding market for home computer games has made 3-D PC video cards available and affordable, so that 3-D visualization is more accessible than ever before to the desktop of a working scientist. Inexpensive desktop stereographic virtual reality techniques can be utilized to view environmental data and model results. For example, with a PC and a 99-cent pair of red/green sci-fi glasses, 3-D objects will pop out of the page in stereo, and can be rotated and zoomed. PMEL's Dr. Albert Hermann has utilized these inexpensive desktop visualization techniques very effectively to reveal the true 3-D location of fish larvae, the steep slopes of seafloor bathymetry, and the vertical motions near a submarine canyon from fisheries-oceanography model results.
A Test bed for NOAA: Because this is the first deployment of virtual reality hardware within NOAA, it provides a test bed for the applicability of the technology to NOAA mission-related research. PMEL's Virtual Reality Laboratory has developed several 3-D stereo animations highlighting ocean and atmosphere dynamics for several NOAA projects and presented them at numerous professional society meetings: Ocean Sciences, American Meteorological Society, Supercomputing '99, American Geophysical Union, Tsunami Hazard Mitigation Meeting, Canadian Statistical Society meeting, NOAATech 2000 and NOAATech 2002, and hosted an open house for NW campus line organizations and nearby research institutions (including the University of Washington and the Joint Institute for the Study of Oceans and Atmospheres). These interactive demonstrations allow users to explore the data sets that NOAA researchers utilize on a daily basis. These virtual reality simulations included:
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CONCLUSIONS
Stereo 3-D rendering of oceanic and atmospheric data is the culmination
of a natural evolution in scientific visualization from simple 2-D Cartesian
plots and early 3-D perspective drawings. Fully stereographic, interactive
3-D rendering takes advantage of the mind's ability to grasp complex environments
to its full extent. The 3-D nature of atmospheric and oceanic data lend
themselves to viewing in full 3-D, and the desktop and ImmersaDesk techniques
used today give the scientist a powerful tool in the quest to better understand
the world around us.
Relevant Web Sites
A
perspective on scientific visualization
Virtual Reality devices in use worldwide
Virtual Reality Start-up package from the National Center for Supercomputing Applications (NCSA)
Media
Contact:
Julie Bedford, NOAA, (202) 482-6096