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This document describes ongoing research at the Center for Coastal Physical Oceanography directed towards utilizing virtual reality methods in studying oceanographic data from the Chesapeake Bay and other regions.
The emerging technology of virtual reality and immersive techniques will change the way data is viewed and analyzed, as well as the way models will be developed and the results interpreted. The current visualization process for three-dimensional data renders plots which may be difficult to understand in a total context due to the size of the vector fields or the complexity of the system being portrayed. However, using virtual reality methods to create and navigate through an artificial world based on the dataset provides an actual sense of presence to the user. While in this virtual environment, direct interaction with the data or with the model producing the fields being viewed via some sort of widget-based interactive user interface is then possible. For example, we could visualize the small scale 3D structure of the first few meters of the ocean surface, watch a simulation of momentum transfer from wind to waves, and then examine the processes from different length scales by interactively changing a model parameter during the visualization.
The National Center for Supercomputer Applications (NCSA) at Champaign-Urbana, Illinois, one of the nationally-funded supercomputer centers, has developed the CAVE (Cave Automatic Virtual Environment) to enable scientists to interact with virtual worlds that have been created from observed data or simulations. The CAVE is a high-resolution projection-screen virtual reality system powered by a Silicon Graphics Onyx parallel-processor computer. The screens are arranged in a 10 foot cube with computer-generated images projected on three walls and a floor. A viewer wears a 6-degrees of freedom head tracker device and stereo-shutter glasses so that the correct projections and perspectives are presented as the viewer moves inside the CAVE. A wand (essentially a computer mouse) held by the viewer allows interaction with the virtual environment. Also available is CAVE simulator software which allows one to develop applications for the CAVE on local platforms.
SIGGRAPH is an annual meeting hosted by the Association for Computing Machinery (ACM) and is devoted to the art and science of computer generated graphics. The initial results of CCPO's VR research effort were presented in the VROOM (Virtual Reality Room) at SIGGRAPH '94 in Orlando the end of July, 1994 by Glen Wheless and Arnoldo Valle-Levinson, both Research Assistant Professors at CCPO, as the project entitled `A Walk Through The Chesapeake Bay'. A fine-grid bathymetry of the Chesapeake Bay was used to create a 3D virtual domain which was then displayed in the CAVE. Viewers were then able to "fly" through this 3D environment and navigate their way through the often abrupt bathymetry of the Bay (Click here for more about this project including an animation of a flythrough). Semi-transparent 3D isosurfaces derived from monthly observations of surface salinity were displayed and animated, showing the seasonal change of salinity throughout the Bay.
Supercomputing '94, the latest conference in the series on high performance computing and communications, took place November 14-18, 1994, at the Washington D.C. Convention Center. The Chesapeake Bay VR Project was showcased at the National Science Foundation's MetaCenter booth. A major addition to the Bay VR exhibit was the display and animation of time dependent salinity fields obtained from a three-dimensional circulation model of the Bay. These fields were rendered as isosurfaces and overlaid upon the graphical representation of the bathymetry. The Princeton Ocean Model, a fully three-dimensional hydrodynamical circulation model with an embedded Mellor-Yamada 2.5 level turbulence closure scheme was used to generate the salinity data.
Researchers at CCPO have fostered a strong collaboration with NCSA scientists and are currently developing an immersive, interactive Chesapeake Bay virtual ecosystem model (CBVEM) using the CAVE technology. Wheless and Eileen Hofmann, Associate Professor, have the lead on the CBVEM project. The visualization framework displayed at SIGGRAPH will serve as the base upon which simulation results from linked submodels of Bay circulation, biological behavior and sediment transport will be displayed. Users will have real-time interactivity with this ecosystem simulation and will be able to control and steer the model as it is running.