V ISUALIZATION C ORNER Editors: Jim X. Chen, [email protected] R. Bowen Loftin, [email protected] VISUALIZATION RESEARCH CHALLENGES A Report Summary By Robert Moorhead, Chris Johnson, Tamara Munzner, Hanspeter Pfister, Penny Rheingans, and Terry S. Yoo EARLY 20 YEARS AGO, THE US NATIONAL SCIENCE FOUN- explains how visualization enables ex- periments of complex phenomena. Vi- N DATION (NSF) CONVENED A PANEL TO REPORT ON VI- sualization reduces and refines data streams, letting us winnow huge vol- SUALIZATION’S POTENTIAL AS A NEW TECHNOLOGY.1 IN 2004, umes of data in applications—for ex- ample, public health surveillance at a THE NSF AND THE US NATIONAL INSTITUTES OF HEALTH (NIH) regional or national level that tracks the spread of infectious diseases. The convened the Visualization Research Visualization’s Value “Virus Structures” sidebar shows how Challenges (VRC) Executive Com- Advances in computing science and visualization helps structural biologists mittee—made up of this article’s au- technology have engendered unprece- understand how virus structure corre- thors—to write a new report. Here, we dented improvements in scientific, bio- lates with strength. Visualizations of summarize that report, available in full medical, and engineering research; such application problems as hurri- at http://tab.computer.org/vgtc/vrc/ defense and national security; and in- cane dynamics and biomedical imag- and in print.2 dustrial innovation. Continuing and ing are generating new knowledge that The VRC report aims to accelerating these advancements will crosses traditional disciplinary bound- require comprehending vast amounts aries. Visualization can also provide • evaluate the progress of the matur- of data and information produced from industry with a competitive edge by ing visualization field, myriad sources.3 Visualization—namely, transforming business and engineer- • help focus and direct future research helping people explore or explain data ing practices into more understand- projects, and through software systems that provide able procedures. • provide guidance on how to appor- a static or interactive visual represen- Although well-designed visualiza- tion national resources as research tation—is critical to achieving this tions can help people enormously, challenges change rapidly in the fast- goal. Visualization designers can ex- naive visualization attempts are all too paced information technology world. ploit the high-bandwidth channel of often ineffective or even actively mis- human visual perception and help us leading. Designing effective visualiza- We explore the state of the field, exam- comprehend information orders of tions is a complex process that requires ine visualization’s potential impact on magnitude more quickly than we a sophisticated understanding of hu- areas of national and international im- would reading raw numbers or text. man information-processing capabili- portance, and present our findings and Visualization is fundamental to un- ties, both visual and cognitive, and a recommendations for the future of this derstanding models of complex phe- solid grounding in the considerable growing discipline. Our audience is nomena, such as multilevel models of body of work that already exists in the twofold: visualization research’s sup- human physiology from DNA to visualization field. Further research in porters, sponsors, and application users whole organs, multicentury climate visualization—and the transfer of ef- on the one hand, and visualization re- shifts, international financial markets, fective visualization methodologies searchers and practitioners on the other. or multidimensional simulations of into the working practice of medicine, Our findings and recommendations re- airflow past a jet wing. The “Charac- science, engineering, and business— flect information gathered from visual- terizing Flow Visualization Methods” will be critical in handling the ongoing ization and applications scientists during sidebar summarizes a study of several information explosion. two VRC workshops, as well as input flow visualization techniques, whereas Although visualization is itself a dis- from the larger visualization community. the “Fusion Plasma Physics” sidebar cipline, advances in visualization lead 66 Copublished by the IEEE CS and the AIP 1521-9615/06/$20.00 © 2006 IEEE COMPUTING IN SCIENCE & ENGINEERING CHARACTERIZING FLOW overall: on average, subjects were fastest and most accurate ISUALIZATION ETHODS when using it. V M This study produced both quantitative results and a basis or decades, researchers have been developing and pub- for comparing other visualization methods, creating more F lishing visualization techniques that advance the state of effective methods, and defining additional tasks to further the art. However, disproportionately few quantitative stud- understand trade-offs among methods. A future challenge is ies compare visualization techniques. Figure A shows the to develop evaluation methods for more complex 3D time- differences between flow visualization methods, showing varying flows. six methods for visualizing the same 2D vector field.1 Sub- jects who participated in the user study performed several Reference tasks, including identifying the type and location of critical 1. D.H. Laidlaw et al., “Comparing 2D Vector Field Visualization Meth- points in visualizations. Assuming roughly equal importance ods: A User Study,” IEEE Trans. Visualization and Computer Graphics, for all tasks, the streamline visualization performed best vol. 11, no. 1, 2005, pp. 59–70. (1) (2) (3) (4) (5) (6) Figure A. Six methods for visualizing the same 2D vector field. They include (1) icons on a regular grid; (2) icons on a jittered grid; (3) layering method inspired by oil painting; (4) line-integral convolution; (5) image-guided streamlines; and (6) streamlines seeded on a regular grid. (Figure courtesy of David Laidlaw, Brown University.) inevitably to advances in other disci- curity, medicine, sociology, and public interpreting information, both quanti- plines. Just as knowledge of mathe- policy, so too is visualization becoming tatively and qualitatively, and with pre- matics and statistics has become indispensable in enabling researchers senting data in a way that most clearly indispensable in subjects as diverse as in other fields. Like statistics, visual- conveys their salient features. Both the traditional sciences, economics, se- ization is concerned with analyzing and fields develop, understand, and abstract JULY/AUGUST 2006 67 V ISUALIZATION C ORNER FUSION PLASMA PHYSICS tokamak is a doughnut-shaped chamber used in fusion A research. During tokamak experimental operation, when a plasma is heated and confined magnetically, events occasionally occur that rapidly terminate the plasma dis- charge. For future experiments, such as the International Thermonuclear Experimental Reactor (ITER), the stored en- ergy will be approximately 100 times greater than in pre- sent-day devices. Thus, these disruptions1 have the potential to severely damage the material wall, especially if the heat flux is highly localized. Figure B shows the results of a simu- lation of a particular disruption in the DIII-D tokamak. The Figure B. Tokamak disruption simulation. The image figure presents visualizations of the temperature isosurfaces, presents visualizations of the temperature isosurfaces, the magnetic field lines, and contours of the heat flux on the the magnetic field lines, and contours of the heat flux wall, which show toroidal and poloidal localization as a re- on the wall. sult of the magnetic field lines’ topology. The localization re- sults from the plasma instability compressing the flux surface in the plasma’s core and then transporting the resulting “hot Reference spots” to the wall. Visualizing the data in 3D shows where 1. S.E. Kruger, D.D. Schnack, and C.R. Sovinec, “Dynamics of the Major the plasma wants to preferentially bulge, enabling the devel- Disruption of a DIII-D Plasma,” Physics of Plasmas, vol. 12, no. opment of improved disruption mitigation techniques. 056113, 2005. data-analytic ideas and package them as Visualization Hardware computationally intensive. A great techniques, algorithms, and software Many of the original report’s hardware deal of academic and industrial re- for various application areas. concerns have been allayed over time search in software volume-rendering However, despite visualization’s im- and by Moore’s law. Processors with algorithms helped the field mature portance to discovery, security, and what used to be considered supercom- and finally made hardware creation competitiveness, support for research puter-class power are now available in feasible. Grant-funded university re- and development in this critical, multi- commodity desktop PCs that cost a few search that began at the State Univer- disciplinary field has been inadequate. thousand dollars. Graphics perfor- sity of New York (SUNY) led to the Unless we recommit ourselves to sup- mance that used to require special-pur- development of an actual product porting visualization research, devel- pose workstations costing tens or through Mitsubishi Electric Research opment, and technology transfer, we’ll hundreds of thousands of dollars is Lab (MERL), culminating in the suc- see a decline in the progress of discov- now available as a commodity graphics cessful spin-off company TeraRecon ery in the other important disciplines card for a few hundred. Fast and cheap (www.terarecon.com). that depend on visualization. As these hardware aimed at the business