Spatial Technologies-3D Modeling and Scientific Visualization31 May, 2006 By: James L. Sipes
Models help clarify complex data and concepts.
Some things are difficult to understand, aren't they? I have a basic idea of what a black hole is, but I don't understand exactly how it works. Do you understand the details of quantum mechanics and the theories of parallel universes? And just what is a quark, anyway? Most of us have a tough time understanding complex scientific theories and mathematical equations, and no amount of verbal explanation seems to help. To help address such issues, scientists are using 3D graphic techniques to create visual representations of the most abstract data.
What is Scientific Visualization?
Scientific visualization is the graphic representation of data designed to foster understanding and insight into that data. This data can be empirical data collected from observers or sensors as well as data derived from computational models. After a computer simulation has been modeled, it then must be interpreted by researchers to comprehend the meaning of the data. We use graphics because our brain has the ability to process a massive amount of information, and visual thinking is the most powerful process.
The digital tools needed to address complex scientific problems integrate geographic information technologies with advanced modeling and visualization tools. Scientific visualization blends a number of different disciplines, including computer graphics, image processing, CAD, GIS, cartography and computer vision. Traditionally, scientists have used GIS to model land forms and spatial relationships, and designers and planners use GIS-based visualization techniques to communicate their design ideas to the public. But much scientific visualization is based on geospatial data, so GIS programs are becoming an important tool for many scientists and researchers as well.
Visualization techniques can help us understand patterns and processes that aren't apparent any other way. For example, change is a fundamental characteristic of every natural process, and the only way to show change is to use some type of animation. The NHC (National Hurricane Center) uses scientific visualization to understand the movements of hurricanes and to share that information with the general public.
Several reasons explain why we are seeing an increase in the use of scientific visualizations. One is that high-cost supercomputers are no longer needed to turn data into imagery. High-end research labs still use supercomputers, but most labs run Unix- and Windows-based platforms. By focusing a computer program on a single task, even desktop PCs have enough processing power to solve very complex problems. The number and variety of scientific visualization programs that run on these systems also has increased tremendously.
The increase in bandwidth has made it easier to share scientific data and do some computing online. Data portals make it easier than ever before to access geospatial data, and this data can be integrated into scientific visualizations.
Most scientific visualization applications make extensive use of the Internet, both as a way to collect and input data and to share results with the public and other researchers. Many scientific visualization programs use VRML (virtual reality modeling language) to share 3D graphics via the Internet.
GPS (global positioning systems) and mobile computing technologies have made it easier to collect data in real-time, and some scientific visualization programs can access real-time geospatial data directly. This ability is critical for organizations involved with predicting weather or preparing for potential hurricanes, severe storms and other natural disasters. One limitation, though, is that this dynamic data typically can only be displayed. It's still beyond the capabilities of most scientific visualization programs to analyze data in real-time.
Realism vs. Accuracy
In recent years, scientific visualizations have improved significantly in terms of both accuracy and realism. Note, however, the big difference between traditional computer graphics and scientific visualization. The level of sophistication in computer graphics often is measured with the ruler of reality—that is, by how closely a 3D world fools people into believing they're seeing something real. With scientific visualization, it's critical that the final imagery accurately reflect the process or theory in question.
Years ago, an Apple scientist and I talked about creating 3D models of natural processes such as rain, wind, gases or the movement of planets. He said that he focused on writing programs that captured the essence of a particular process. The final graphic representations were simply a way to verify the accuracy of the written code.
An extensive range of graphics software is available for visualization. Some programs are geared to a specific industry or type of use. Others take a broader approach and provide digital tools to help create different types of imagery. ESRI's ArcView 3D Analyst, for example, can be used to create 3D images of geospatial data for a variety of disciplines.
Many scientific visualization programs are based on open-source standards, and this approach makes it easier for scientists to modify the software to meet their needs. In the academic environment, sharing software and making source code available has been commonplace for decades. That does not mean all scientific visualization programs are available for free, however.
One thing I quickly realized about scientific visualization is that the software developers were concerned more with functionality than ease of use. This type of software is frequently developed by the people who intend to use it. Some programs are written in Fortran or C programming language, and they have rudimentary graphical user interfaces—at best.
SVS (Scientific Visualization Studio) works with scientists at NASA's Goddard Space Flight Center to develop visualizations of their research. Visualizations created by SVS are available from its Web site as animations, still images or both. The SVS Image server is used to share this information with the public (figure 1), primarily elementary and high schools seeking to meet the National Science Education Content Standards. The visualizations developed by SVS also are incorporated into educational software and exhibits at museums, interpretive centers and science centers.
Figure 1. This composite illustration shows a view of the planet Neptune as seen from Triton, one of its moons. This 3D view was created using images from the Voyager spacecraft. Image courtesy of NASA.
Among the information available from the SVS image server are programs such as World Wind 1.3, open-source Windows software from NASA that can be used to visual scientific data and geospatial information. It can access Landsat satellite imagery and Shuttle Radar Topography Mission data and link both with other geospatial data (figure 2).
Figure 2. SRTM and Landsat 7 data was combined to create a 3D visualization of Mt. St. Helens, WA, using World Wind. Image courtesy of NASA Ames Research Center.
The scientific visualization team at the U.S. Army Research Laboratory promotes the use of scientific visualization within the Department of Defense. Most simulations they create are physics based, and they develop new techniques for using high-performance computing technology. The team also works with CFD (computational fluid dynamics), penetration mechanics, battlefield troop movement, artificial terrain generation and explosive effects.
EMVL (Environmental Modeling and Visualization Laboratory) of the EPA (Environmental Protection Agency) provides high-performance computing resources for agency researchers exploring environmental issues. EMVL staff also provides training and support for these researchers. EPA has made significant efforts in recent years to integrate its GIS tools with those for scientific visualization. The EPA ESDLS (spatial data library system) functions as EPA's node that connects with the FGDC's (Federal Geographic Data Committee's) national geospatial data clearinghouse.
VTK (Visualization ToolKit) is an open-source software package used for 3D computer graphics, image processing and visualization (figure 3). The GeneSpring Analysis Platform was developed to address biological questions. IRIS Explorer is a powerful tool for developing customized visualization applications. Scilab is a scientific software package for numerical computations. VMD, a molecular visualization program, displays, animates and analyzes biomolecular systems.
Figure 3. Chandu Karadi, Ph.D., created this 3D-rendered image of a frog using the Visualization Toolkit. This research is part of the NSF-funded Virtual Creatures Project.
Most of the research at the State University of New York at Stony Brook focuses on volume visualization techniques and applications of virtual reality. The lab has developed VolVis, a volume-visualization system that includes a number of different algorithms that can be used in disciplines such as biology, medicine and physics (figure 4).
Figure 4. Image from 3D virtual colonoscopy, a project from Stony Brook s Visualization Lab. A scanner is used to obtain 2D images of the human abdomen, and these images are combined to create 3D volumes.
The MIT (Massachusetts Institute of Technology) department of aeronautics and astronautics has developed several scientific visualization programs over the years. Many focus on CFD: Visual3, a 3D CFD visualization system, and pV3, a 3D-distributed CFD visualization system for supercomputers, parallel machines and workstation clusters.
The Scientific Visualization Lab at Georgia Tech University is a multidisciplinary facility used by researchers in many departments across campus. Some of the visualization projects include efforts that focus on photorealism, ray tracing, terrain modeling, atmospheric simulations, 3D molecular modeling and fluid dynamics.
NAS (NASA advanced supercomputing) division uses some of the fastest supercomputers in the world to explore questions about science. NAS focuses on space exploration and the science needed to support the space shuttle, exploration vehicles and emergency response capabilities. NAS also works to improve weather and climate models that can be used as part of NASA's Earth science work in climate and weather modeling.
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The ICA (International Cartographic Association) Commission on Visualization and ACM–SIGGRAPH (Association for Computing Machinery Special Interest Group on Graphics) work together to explore the integration of GIS, visualization and Web-based communication tools.
Researchers at the University of Calgary's ESD (evolutionary and swarm design) research group are developing simulations that depict swarming behaviors. These models, which describe how birds fly and fish swim, have practical applications. For example, architects can study swarming and flocking behavior to understand the movement of crowds. The collective intelligence that different species display during their swarming and flocking may be applicable to other problems such as computational theory. Computer scientists use swarm modeling to study new techniques for developing computer networks and for implementing artificial intelligence.
Learning about Visualization
Those interested in learning more about scientific visualization have several options. Most universities have some type of scientific visualization program, as do federal agencies such as NOAA (National Oceanic and Atmospheric Administration) and NHC (National Hurricane Center). One of the best venues for learning about cutting-edge scientific visualization is the IEEE (Institute of Electrical and Electronics Engineers) Visualization Conference and Information Visualization Symposium, Vis 2006.
Vis 2006 brings together researchers and practitioners involved with different aspects of scientific modeling and research. The conference includes workshops, tutorials, papers, panels, demonstrations, posters and exhibitions. Visualization types covered include environmental sciences, life sciences, physical sciences, engineering, fluid dynamics, social and information sciences, mathematical computations and virtual environments.
Visualizing the Future
Scientific visualization will continue to expand as scientist seek to make complex issues more understandable. Technology is improving dramatically, and our understanding of the science behind critical problems such as environmental changes also is increasing. Because so many of these environmental changes are spatially oriented, you can expect to see the worlds of GIS and scientific visualization work together to expand the capabilities of both.
One term I am starting to see a lot is geovisualization, which refers specifically to developing 3D graphic representations of geospatial information. You'll be hearing much more about geovisualization in the next couple of years.
James L. Sipes is the founding principal of Sand County Studios in Seattle, Washington, and senior associate with EDAW in Atlanta, Georgia. Reach him at firstname.lastname@example.org.