- Email: [email protected]
Delivering data interpretation: From GFLOPS to insight
Comput & Graphics Vol. 17, No. 1, pp. 23-30, 1993
0097-8493/93 $6.00 + .iX) © 1993 Pergamon Press Ltd.
Printed in Great Britain.
Supercomputing and Visualization DELIVERING DATA INTERPRETATION: FROM GFLOPS TO INSIGHT LouIs H. TURCOTTE Computer Sciences Corporation, Army High Performance Computing Research Center, USACE Waterways Experiment Station, 3909 Halls Ferry Road, Vicksburg, MS 39180-6199 and BRADLEY M. COMES Scientific Visualization Center, USACE Waterways Experiment Station, 3909 Halls Ferry Road, Vicksburg, MS 39180-6199 Abstract--The quest to deliver computers with teraflop computing power introduces several ancillary technical challenges. One of the most obvious challenges involves the capability to interpret the enormous quantity of data resulting from investigations using today's supercomputers. Data interpretation requires several techniques: printouts, graphics, scientific visualization, and multi-sensory systems. The need to more efficiently interpret large datasets led the US Army Engineers Waterways Experiment Station to establish a scientific visualization center. This center, established in the fall of 1990, provides assistance with the adaptation and implementation of emerging data interpretation techniques to the 800+ researchers at the national laboratory. This paper summarizes the collective experiences of The Center• Experience with commercial visualization software, public domain software, internally developed software, visualization techniques, virtual reality systems, and hardware facilities is presented. I. INTRODUCYION Rapidly advancing computational capabilities are allowing researchers to consider numerical modeling and simulation problems that will exceed previous efforts by several orders-of-magnitude. The national goal to produce computers capable of teraflop performance by 1995 will surely lead researchers to attempt significantly more complicated numerical studies. The President's Office of Science and Technology [2] summarizes the advancing computational environment as:
gent fields of: computer graphics, image processing, computer vision, computer-aided design, signal processing, and user interface studies." The culmination of rapidly advancing computational resources, more sophisticated numerical modeling projects, and the complexity of the new techniques required to interpret information from these studies led the US Army Engineers Waterways Experiment Station (WES) to establish the Scientific Visualization Center (SVC) in early 1990. This center serves as the primary visualization resource for the 800+ researchers at the national laboratory. The Center's primary mission is to assist researchers with the adaptation and implementation of advanced data interpretation techniques. Additional energies are directed towards the exploration of emerging methods. The collective experiences realized by The Center over the last 2 years are reviewed. Four components that characterize The Center (charter, facility, application experiences, and research ) are presented.
"Recent advances offer the potential for a thousand-fold improvement in useful computing capability and a hundredfold improvement in available computer communications capability by 1996." Additional evidence is offered in this report[2], and reproduced in Fig. 1, of the ever-growing computational requirements that will be necessary to address " G r a n d Challenge" problems. As our computational efforts increase, the need to adapt data interpretation methods that allow the researcher to more productively and reliably analyze their data becomes paramount. Effective data interpretation techniques are necessary to make the results generated by these complicated numerical modeling efforts more palatable. In 1987 a panel report[l] was funded by the National Science Foundation. The report classified a category of data interpretation that offers significant potential for use with the next generation of computer models. The panel defined "Visualization" as follows:
2. CENTER C H A R T E R The establishment of a central visualization center for a large, diverse research c o m m u n i t y represents a significant challenge. The researchers at the WES are located in six separate laboratories; Coastal Engineering Research Center, Environmental Laboratory, Geotechnical Laboratory, Hydraulics Laboratory, Information Technology Laboratory, and Structures Laboratory. These laboratories perform engineering studies in a wide range of topics; examples include hydrodynamic modeling of rivers/esturaries/coastlines, sedimentation, terrain analysis, coastal processes, water quality modeling, finite element analysis, image processing, wetlands modeling, soil-structure interaction, and weapons effects. The goal to assist over 800+ re-
"Visualization is a method of computing• It transforms the symbolic into the geometric, enabling researchers to observe their simulations and computations• Visualization offers a method for seeing the unseen. It enriches the process of scientific discovery and fosters profound and unexpected insights. •.. Visualization unifies the largely independent but conver23
24
Louis H. TURCOTTEand BRADLEYM. COMES Grand Challenges Computer P e z f o r m a n c e i n Billions of O p e r a t i o n s per s e c o n d
Fluid Turbulence Pollution Dispersion Human Genome ocean Circulation a n t u m Ch romodyna mic e m i c o n d u c tot M o d e l i n c o m b u s t i o n systems i s i o n and c o g n i t i o n
I000
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structural Biology
I I I
I Vehicle signature
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i0
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I
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Airfoil
Chemical Dynamics
Design
0.i
Speech and
g Natural 72 Hour Weather I E s t i m a t e of H l g g s Boson Mass
Language
3D Plasma Modeling
2D Plasma Modeling
1980
1990
2000
Fig. 1. Performance requirements for grand challenge problems. From the Committee on Physical, Mathematical, and EngineeringSciences,Ot~ce of Scienceand Technology,Grand Challenges: High Performance Computing and Communications ( 1992). searchers with a small staff of 5-10 people necessitated that a charter be developed. This charter outlines The Center's goals and missions and serves as the guide for all activities of The Center. The critical components that influenced the development of the charter are shown in Fig. 2. Figure 2 illustrates the delicate balance between the humans and the machines necessary to deliver visualization to a mature research environment. The chief goal of The Center is to combine a comprehensive hardware environment with experts in visualization and video production to improve the productivity and capability of the individual researcher. Combining visualization experts with a critical mass of computer hardware and software creates the aggregate synergy necessary to effectively implement visualization at a national laboratory.
Several goals for The Center were identified during the early planning stages. These goals were developed using information acquired from the relatively few other visualization centers in the world. The goals are: • to offer specialized expertise in visualization technology; • to offer hardware and software that are prohibitively expensive for the individual researcher; • to use the WES's FDDI computer network (8.2 miles in length) to create a "working link" between distributed installations, the supercomputer, and The Center; • to establish a visualization center recognized as a premier facility; and • to contribute to the advancement of visualization as a discipline. Five types of initiatives were classified to achieve these goals. These initiatives completely characterize the activities of The Center and identify the major work components of a centralized visualization center. They are • • • • •
Fig. 2. Components of visualization.
collaborative projects, educational activities, cooperative projects, investigative research and development projects, and service activities.
Collaborative projects predominate the activity of The Center. A collaborative project involves a 4-6 week highly interactive visualization project between a researcher and one or more of The Center's experts.
Deliveringdata interpretation These projects facilitate the transfer of technology to the researcher. A collaborative project typically results with the production of a high quality video depicting some aspect of their research or the identification of a day-to-day visualization tool that improves the capabilities and productivity of the researcher. Working side-by-side on a daily basis, the visualization specialist and the researcher explore and evaluate different data interpretation strategies. Upon conclusion of this collaborative effort the researcher has benefited in two important ways. The skills acquired by the researcher during this collaboration can be employed daily for subsequent projects conducted in the researchers own workroom. Additionally, during the collaboration the researcher is exposed to the numerous hardware and software technologies that may be employed and are available via The Center. These collaborative projects also provide benefits to The Center. The never ending project diversity continuously challenges the visualization center staff and provides the basis for continued professional growth. Educational activities are used to present pertinent information to a group. Briefings and overviews are presented in topics such as software/hardware products, standards, and animation techniques. Workshops are provided in topics such as X, GUI's, cognitive issues, and distributive visualization environments. Seminars conducted by nationally recognized visualization experts are also sponsored. Members of The Center are also expected to regularly publish articles both locally (WES newsletters) and nationally (conferences, journals, etc). Finally, The Center has an aggressive management briefing program. This program is used to demonstrate to management the productivity benefits that result from the application of visualization tools. One of the primary goals is to help the researcher justify the investment necessary to implement visualization technologies within their daily work environment. Cooperative projects are used to develop and strengthen relationships with external visualization experts. These cooperative projects typically involve a shared development burden for a research project or a transfer of capabilities between groups. Sharing experiences with outside groups exposes The Center's staff to additional techniques and strengthens the overall knowledge of both groups. In addition, interactions between the limited number of specialists who provide visualization expertise on a day-to-day basis and who are equipped with extensive hardware and software facilities accelerates the advancement of scientific visualization as a science. Research and development projects assure that the staff continues to be exposed to the latest data interpretation technologies and techniques. Most of The Center's research and development effort is directed towards extending the data interpretation capabilities available to WES researchers. However, The Center staff is encouraged to direct a portion of their energy towards independent research projects as a compliment to their service oriented tasks.
25
Service activities reflect the commitment of The Center to assist with the more mundane, yet vital, tasks related to visualization. Such activities as: • providing assistance with both hardware and software that is available via The Center, • serving as the repository for public domain software, • evaluating existing standards and suggesting a set of standards that produce a managable working environment, • providing expertise in evaluating new visualization techniques and technologies, and • providing the interface between the researcher and the scientific illustrators available via The Center, are representative of the types of day-to-day requests and initiatives that roundout The Center's activities. These "real world" diversions prevent The Center from becoming detached from the daily requirements of the researcher. The Center is, therefore, forced to focus on actual issues rather than "hypothesized" demands. 3. FACILITIES Establishing a premier visualization center requires a sizable investment in both human expertise, visualization hardware/software, and video production hardware. The lack of sufficient investment in any of these critical items will tremendously restrict the ability to offer the visualization solutions required to support a mature research community. The WES SVC represents a multimillion dollar investment in hardware, software, and people. The success of such an effort is completely dependent on a commitment from senior management. The requirement to interact with a diverse set of researchers mandates that staff members in the visualization center be capable of communicating effectively in numerous technical subjects. Visualization, itself, is a multidisciplinary science and exercises skills in such fields as computer graphics, video, physics, engineering, numerical methods, art, and cognition. The selection of an interdisciplinarystaff should be regarded as the most important aspect of supporting any visualization effort. The Center's staffincludes individuals with graduate degrees in computer science, civil engineering, chemical engineering, engineering mechanics, and computer engineering. Additional staff members are experts in video production and scientific illustration. The hardware diagrammed in Fig. 3 represents workstations, peripherals, networks, and mass storage equipment located in The Center. The requirement for specialized 3-D visualization workstations is obvious. The majority of the workstations are from Silicon Graphics, Inc. However, The Center also utilizes an Apple Macintosh, a Sun workstation, and several staff members have IBM / RS6000 and Next workstations. The Center supports several output devices that may be considered prohibitively expensive for the individual researcher. A Canon CLC 500 color copier serves as both an output device and a color scanner. A Solitare 8xp provides both 35 mm and 4 × 5 film
LouIs H. TURCOTTE and BRADLEYM. COMES
26
Seientifie Visualization Center
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Fig. 3. Visualization hardware. output for high quality reproduction and presentations. A Tektronix Phaser III printer provides high quality color postscript output. A standard laser printer, high speed dot matrix printer, and a Tektronix 4693DX serve traditional output requirements. An Abekas A60 real time disk system provides the link between the computer generated images and the video production facility. All of these devices are attached to a private ethernet. Figure 4 summarizes the broadcast quality video production facility. The nature of both the civilian and military research performed by the WES mandates that high quality video production methods be used to meet standards that are necessary for use in public policy forums. The critical link between the computational hardware and the video hardware is provided by an
Abekas A60 real time disk system. This system holds approximately 30 seconds of animation (at 30 frames/ second). Video frames residing on the A60 may subsequently be transferred to either analog or digital video tape at operator selectable speeds. As indicated by Fig. 4, the video production capabilities include all the components found in any commercial video production studio. Effectively delivering visualization solutions as part of a day-to-day routine creates ancillary technical challenges. The massive amounts of data being generated and analyzed by a supercomputer and subsequently needed for visualization can saturate network bandwidth. The Center has a dedicated FDDI link to the local CRAY supercomputer. As indicated by Fig. 3, the FDDI link has two access paths to The Center.
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Deliveringdata interpretation A separate FDDI connection is provided to a SGI file server that manages the disk farm used by The Center. This connection is used to migrate large quantities of data from the supercomputer to The Center. All other network traffic from The Center to outside networks is routed through a separately attached NSC FE640 router. This network topology has satisfied many of the data movement problems that typify visualization. The Center, however, plans to replace the internal ethernet with a private FDDI network. The second mandatory hardware requirement results from needing enormous volumes of disk space to support visualization, specifically animation. A simple calculation serves to validate the disk requirements. A 24-bit megapixel display requires about 2 MBytes to store a single frame of information. Video animation requires 30 frames/ second. Therefore, a 30 second computer animation can require as much as 2 GBytes of data storage. Presently, The Center has approximately 20 GBytes of online disk and plans to acquire a 100 GByte optical disk farm. The last critical component of a visualization center is the availability of software solutions. The initial goal of The Center was to provide rapid adaptation of visualization within the WES research community. This goal created a requirement to provide off-the-shelf solutions that could be implemented rapidly. The strategy was to acquire commercial software and freely available software. The Center's library of commercial software includes MPGS from CRAY Research, Interactive Volume Modeler from Dynamic Graphics, Wavefront's Advanced Visualizer and Data Visualizer, Bechtel's Walkthru, PV-Wave from Precision Visuals, and Unigraph from Uniras. Freely available software includes Khoros from the University of New Mexico, P3D from the Pittsburg Supercomputing Center, several programs from NCSA, lmagetools from the San Diego Supercomputer Center, and Exvis from the University of Massachusetts at Lowell. NASA developed tools include FAST and PLOT3D. These software solutions have been augmented by internally developed software for problems that are not readily solved using commercial software. The use of commercial and freely available software is not a panacea. "'Canned" solutions will usually require unique techniques to address the individual needs of the researcher. Additionally, the choice of software and the complexity of these multipurpose solutions may prove to be an obstacle for the researcher. The visualization expert's role is to help with the selection of the appropriate software tool and to teach the researcher how to use the tool most effectively for their problem. The use of"canned" solutions, when appropriate, minimizes the long-term support requirements for The Center and allows the staffto address problems that do not have off-the-shelf solutions.
4. APPLICATION EXPERIENCES Experience accumulated from numerous collaborative projects has confirmed the axiom that there is
27
no single approach or solution that serves every need. The applications surveyed here represent a smorgasbord of approaches. Experience has proven that there are many facets of visualization that can only be developed from experience. The appropriate choice of colors and text fonts that transfer to video is one example. The use of format translators to move data between various software products and to video equipment is another example. These skills are difficult to summarize but play an important part in the overall efficiency and quality of the visualization product. Several visualization projects completed using commercial, public domain, and internally developed software are summarized. Visualization from CADD models, numerically generated scientific data, field data acquisitions, and artistic representations are presented. Figure 5a depicts the numerical results from a 3-D water quality model of the Chesapeake Bay. The water quality investigation required evaluating the behavior of over 20 different parameters (dissolved oxygen, salinity, chlorophyll, diatoms, etc. ). This frame shows the dissolved oxygen concentrations for a specific time during a one year simulation. Red regions signify zones with zero dissolved oxygen. The bay is approximately 200 miles long with an average channel depth of 75 feet. Therefore, the visual model has been dimensionally distorted. The widths of the tributaries were distorted to be visually discernable and the depth has been exaggerated. These dimensional distortions are characteristic of data sets that represent real world models. This visualization was produced using results from a 3-D finite difference model of the bay and the Interactive Volume Modeler software from Dynamic Graphics, Inc. Visualization of data produced by the water quality model of the bay will be used to assist with the evaluation of the effectiveness of nutrient reduction strategies to improve the water quality in the bay. Figure 5b is a frame from a 3-D animation depicting the salinity distribution in the Galveston Bay induced by daily tidal cycles. This frame illustrates the output from a software tool that utilizes distributed computing. The frame was generated using MPGS from CRAY Research, Inc. MPGS is a visualization tool that provides an interactive CRAY-SGI distributed data exploration environment. Results from the 3-D finite element model of the bay can he studied interactively to improve the accuracy of the model and provide more insight into the physical processes being modeled. This model is being used to study the effects channel dredging will have on oyster beds in the bay. Figure 5c is a frame from a 2-D animation produced from a time dependent study of a section of the lower Mississippi River. This frame depicts the river's bed elevation at one instance in time. The visualization software/tool was internally developed and is representative of the occasional problem that has no commercial visualization solution. This model is being used to evaluate potential options that will reduce maintenance dredging for deep draft navigation. Alternate placements of submerged dikes were rapidly evaluated
LouIs H. TURCOTTEand BRADLEYM. COMES
28
to determine their effectiveness towards controlling sediment movement in the river. Figure 5d was produced using a NASA developed CFD visualization tool named FAST. This 2-D frame depicts the affects induced by a series of wells on the unconfined flow of groundwater in a river influenced aquifer near a slurry trench. The application of a visualization tool designed for studies in aerodynamics to studies in groundwater modeling demonstrates the potential benefits of cooperative projects between visualization groups. Figure 5e was generated using a visualization tool available to the public at no charge. Using software developed by NCSA, researchers are visualizing the affects of an accidental explosion within an underground munitions storage tunnel. This 2-D frame shows the temperature waves propagating within the tunnel for one instance during the simulation. Figure 5f represents the level of contaminant measured from a leaking underground storage tank. This 3-D visualization, produced using Interactive Volume Modeler from Dynamic Graphics, is use to determine site characteristics for numerical model calibration, scenerio analysis, and subsequent clean up and treatment of hazardous materials. Shown in the frame are computer interpolated contours created from actual field data. When using field collected data, visualization experts must be careful to verify that the final representation is more than visually pleasing. Numerous sensitivity studies were performed prior to accepting the results depicted by this frame. The capability of sophisticated software to display information rapidly should not distract practitioners of visualization from verifying that the information is scientifically accurate. Figure 5g depicts a 3-D CADD model developed for a proposed military housing facility. The use of CADD walk-throughs and fly-arounds represent another use of visualization. Visual animations of proposed construction projects can be used to refine and improve the construction sequences, thus producing significant cost savings. This animation was produced using Bechtel's Walkthru software. Figure 5h is a frame from an animation used to describe a complex beach erosion/wave testing sequence. The frame shown depicts the physical location of test sensors within a physical wave tank. Created by a scientific illustrator, this type of visualization has become a very effective method for communicating complex processes/events. Using Wavefront's Advanced Visualizer software, the illustrator used photos and design plans to recreate the layout of the test facility. 5. RESEARCH
The rapid growth in size and complexity of numerical models being employed will continue to challenge existing interpretation methods. Considerable research and development efforts must be directed towards resolving these interpretation impediments. The rate at which a researcher can consume information visually will eventually hinder productivity. Already, research
is being conducted in topics such as virtual reality, multi-sensory environments, auditorialization, cognitive issues, intelligent systems, and voice recognition. The integration of additional human senses such as hearing and feeling with vision will no doubt create a richer interpretation experience in the future. The use of virtual reality for experiencing three-dimensional data sets has received considerable attention in the last 2 years. Virtual reality systems combine stereo viewing display technologies with spacial location sensors to produce the simulation of a "virtual" world. The Center's efforts have been directed at two different hardware configurations. One system combines the Eyephone and Datagiove manufactured by VPL. The second system is manufactured by Fake Space Labs and combines a "BOOM" (Binocular Omni-Orientation Monitor) with the VPL Dataglove. The Eyephone system supports color, albeit at a very crude resolution (360 × 240). The BOOM system is black and white but provides higher resolution (720 X 486 ). Initial observations indicate that the color system offers an attractive technology for such applications as building walkthroughs and games. The BOOM system has greater potential for scientific data interpretation. The high resolution combined with the more ergonomically appealing viewing apparatus has been much better accepted and is more reliable than the helmet-based Eyephone system. The realization that teams of scientists involved in coordinated research projects will be distributed geographically provides a clue to one potential use of virtual reality. Collaborating researchers on opposite sides of the country, or world, will be able to "share" the data interpretation experience. Researchers connected via long haul networks will be simultaneously emerged in the same volume of data and will be able to more effectively communicate their premonitions with colleagues. They will be able to see the other person (a computer generated representation of the other person) looking and pointing at the data! Another research project, also in the initial phases, is attempting to demonstrate the benefits of augmenting the visual interpretation process with sound. This research effort is investigating the use of audio as an additional sense queue for interpreting complex numerical data sets. As data sets continue to increase in size and complexity, the use of additional human senses to augment the visual data representation will become of greater necessity. Correlating sound with the speed of a fluid or the magnetic forces surrounding an atom are a couple of potential uses for audio. The need for methods that provide effective interpretation of multiparametric data sets continues to challenge the present technology. The requirement to correlate and understand the complex relationships between as many as 20 constituents in water quality models continues to challenge us. The ability to provide real time animation at the desktop is another capability that is presently limited. These are but a few of the challenges that confront the widespread adaptation and implementation of visualization technologies. As these
Delivering data interpretation
29
i
Fig. 5a. Cheml~ke Bay. Fig. 5d. Groundwater flow near series of wells.
Fig. 5b. Galveston Bay,
Fig. 5e. Accidental explosion in Munitions Tunnel.
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30
LouIs H. TURCOTTEand BRADLEYM. COMES entertainment characteristic, or as Walt Disney once noted: "I'd rather entertain people, and hope they learn, than try to teach people and hope they are entertained." 6. SUMMARY
The availability of a centralized visualization center has dramatically improved the capabilities of our researchers. Stallings [ 3] has summarized the use of visualization eloquently: "The videocassette is mighter than the viewgraph. A stunning image can have more impact than a long list of data, no matter how well researched."
Fig. 5g. CADD model of military housing facility.
The continuously expanding complexity of numerical models and the corresponding advances in raw computation power will mean that specialists in sophisticated data interpretation technologies will more frequently be included as integral parts of the research team. Transforming numerical calculations performed at G F L O P rates into scientific insight will require increasingly greater resources, both hardware and human.
Acknowledgements--The authors would like to acknowledge the contributions from the staffofthe Scientific Visualization Center and the individual researchers who provided input for this paper. The Army's High Performance Computing Research Center is operated by the University of Minnesota and funded by the Army Research Office, Contract Number DAAL03-89-C-0038. Permission was granted by the Chief of Engineers, U.S. Army Corps of Engineers, to publish this information. REFERENCES
Fig. 5h. Wave testing facility.
issues are identified and successfully addressed, more and more researchers will begin to realize the benefits from these radically new and different approaches to data interpretation. Consumption of these new tools will occur more rapidly when they possess an innate
1. B. H. McCormick, T. A. DeFanti, and M. D. Brown, Visualization in Scientific Computing. ProceedingsACM S1GGRAPH 21(6), p. 3. (1987). 2. Committee on Physical, Mathematical, and Engineering Sciences, Office of Science and Technology, Grand Chal-
lenges: High Performance Computing and Communications, pp. 5-7 (1992). 3. J. Stallings, Trends in Scientific Visualization: Is Beauty
Also Truth. Supercomputing Review, pp. 36-39. (August, 1990).
0097-8493/93 $6.00 + .iX) © 1993 Pergamon Press Ltd.
Printed in Great Britain.
Supercomputing and Visualization DELIVERING DATA INTERPRETATION: FROM GFLOPS TO INSIGHT LouIs H. TURCOTTE Computer Sciences Corporation, Army High Performance Computing Research Center, USACE Waterways Experiment Station, 3909 Halls Ferry Road, Vicksburg, MS 39180-6199 and BRADLEY M. COMES Scientific Visualization Center, USACE Waterways Experiment Station, 3909 Halls Ferry Road, Vicksburg, MS 39180-6199 Abstract--The quest to deliver computers with teraflop computing power introduces several ancillary technical challenges. One of the most obvious challenges involves the capability to interpret the enormous quantity of data resulting from investigations using today's supercomputers. Data interpretation requires several techniques: printouts, graphics, scientific visualization, and multi-sensory systems. The need to more efficiently interpret large datasets led the US Army Engineers Waterways Experiment Station to establish a scientific visualization center. This center, established in the fall of 1990, provides assistance with the adaptation and implementation of emerging data interpretation techniques to the 800+ researchers at the national laboratory. This paper summarizes the collective experiences of The Center• Experience with commercial visualization software, public domain software, internally developed software, visualization techniques, virtual reality systems, and hardware facilities is presented. I. INTRODUCYION Rapidly advancing computational capabilities are allowing researchers to consider numerical modeling and simulation problems that will exceed previous efforts by several orders-of-magnitude. The national goal to produce computers capable of teraflop performance by 1995 will surely lead researchers to attempt significantly more complicated numerical studies. The President's Office of Science and Technology [2] summarizes the advancing computational environment as:
gent fields of: computer graphics, image processing, computer vision, computer-aided design, signal processing, and user interface studies." The culmination of rapidly advancing computational resources, more sophisticated numerical modeling projects, and the complexity of the new techniques required to interpret information from these studies led the US Army Engineers Waterways Experiment Station (WES) to establish the Scientific Visualization Center (SVC) in early 1990. This center serves as the primary visualization resource for the 800+ researchers at the national laboratory. The Center's primary mission is to assist researchers with the adaptation and implementation of advanced data interpretation techniques. Additional energies are directed towards the exploration of emerging methods. The collective experiences realized by The Center over the last 2 years are reviewed. Four components that characterize The Center (charter, facility, application experiences, and research ) are presented.
"Recent advances offer the potential for a thousand-fold improvement in useful computing capability and a hundredfold improvement in available computer communications capability by 1996." Additional evidence is offered in this report[2], and reproduced in Fig. 1, of the ever-growing computational requirements that will be necessary to address " G r a n d Challenge" problems. As our computational efforts increase, the need to adapt data interpretation methods that allow the researcher to more productively and reliably analyze their data becomes paramount. Effective data interpretation techniques are necessary to make the results generated by these complicated numerical modeling efforts more palatable. In 1987 a panel report[l] was funded by the National Science Foundation. The report classified a category of data interpretation that offers significant potential for use with the next generation of computer models. The panel defined "Visualization" as follows:
2. CENTER C H A R T E R The establishment of a central visualization center for a large, diverse research c o m m u n i t y represents a significant challenge. The researchers at the WES are located in six separate laboratories; Coastal Engineering Research Center, Environmental Laboratory, Geotechnical Laboratory, Hydraulics Laboratory, Information Technology Laboratory, and Structures Laboratory. These laboratories perform engineering studies in a wide range of topics; examples include hydrodynamic modeling of rivers/esturaries/coastlines, sedimentation, terrain analysis, coastal processes, water quality modeling, finite element analysis, image processing, wetlands modeling, soil-structure interaction, and weapons effects. The goal to assist over 800+ re-
"Visualization is a method of computing• It transforms the symbolic into the geometric, enabling researchers to observe their simulations and computations• Visualization offers a method for seeing the unseen. It enriches the process of scientific discovery and fosters profound and unexpected insights. •.. Visualization unifies the largely independent but conver23
24
Louis H. TURCOTTEand BRADLEYM. COMES Grand Challenges Computer P e z f o r m a n c e i n Billions of O p e r a t i o n s per s e c o n d
Fluid Turbulence Pollution Dispersion Human Genome ocean Circulation a n t u m Ch romodyna mic e m i c o n d u c tot M o d e l i n c o m b u s t i o n systems i s i o n and c o g n i t i o n
I000
i00
structural Biology
I I I
I Vehicle signature
Pharmaceutical Design I
i0
I ULSI D e s i g n
I
48 H o u r Weather
Airfoil
Chemical Dynamics
Design
0.i
Speech and
g Natural 72 Hour Weather I E s t i m a t e of H l g g s Boson Mass
Language
3D Plasma Modeling
2D Plasma Modeling
1980
1990
2000
Fig. 1. Performance requirements for grand challenge problems. From the Committee on Physical, Mathematical, and EngineeringSciences,Ot~ce of Scienceand Technology,Grand Challenges: High Performance Computing and Communications ( 1992). searchers with a small staff of 5-10 people necessitated that a charter be developed. This charter outlines The Center's goals and missions and serves as the guide for all activities of The Center. The critical components that influenced the development of the charter are shown in Fig. 2. Figure 2 illustrates the delicate balance between the humans and the machines necessary to deliver visualization to a mature research environment. The chief goal of The Center is to combine a comprehensive hardware environment with experts in visualization and video production to improve the productivity and capability of the individual researcher. Combining visualization experts with a critical mass of computer hardware and software creates the aggregate synergy necessary to effectively implement visualization at a national laboratory.
Several goals for The Center were identified during the early planning stages. These goals were developed using information acquired from the relatively few other visualization centers in the world. The goals are: • to offer specialized expertise in visualization technology; • to offer hardware and software that are prohibitively expensive for the individual researcher; • to use the WES's FDDI computer network (8.2 miles in length) to create a "working link" between distributed installations, the supercomputer, and The Center; • to establish a visualization center recognized as a premier facility; and • to contribute to the advancement of visualization as a discipline. Five types of initiatives were classified to achieve these goals. These initiatives completely characterize the activities of The Center and identify the major work components of a centralized visualization center. They are • • • • •
Fig. 2. Components of visualization.
collaborative projects, educational activities, cooperative projects, investigative research and development projects, and service activities.
Collaborative projects predominate the activity of The Center. A collaborative project involves a 4-6 week highly interactive visualization project between a researcher and one or more of The Center's experts.
Deliveringdata interpretation These projects facilitate the transfer of technology to the researcher. A collaborative project typically results with the production of a high quality video depicting some aspect of their research or the identification of a day-to-day visualization tool that improves the capabilities and productivity of the researcher. Working side-by-side on a daily basis, the visualization specialist and the researcher explore and evaluate different data interpretation strategies. Upon conclusion of this collaborative effort the researcher has benefited in two important ways. The skills acquired by the researcher during this collaboration can be employed daily for subsequent projects conducted in the researchers own workroom. Additionally, during the collaboration the researcher is exposed to the numerous hardware and software technologies that may be employed and are available via The Center. These collaborative projects also provide benefits to The Center. The never ending project diversity continuously challenges the visualization center staff and provides the basis for continued professional growth. Educational activities are used to present pertinent information to a group. Briefings and overviews are presented in topics such as software/hardware products, standards, and animation techniques. Workshops are provided in topics such as X, GUI's, cognitive issues, and distributive visualization environments. Seminars conducted by nationally recognized visualization experts are also sponsored. Members of The Center are also expected to regularly publish articles both locally (WES newsletters) and nationally (conferences, journals, etc). Finally, The Center has an aggressive management briefing program. This program is used to demonstrate to management the productivity benefits that result from the application of visualization tools. One of the primary goals is to help the researcher justify the investment necessary to implement visualization technologies within their daily work environment. Cooperative projects are used to develop and strengthen relationships with external visualization experts. These cooperative projects typically involve a shared development burden for a research project or a transfer of capabilities between groups. Sharing experiences with outside groups exposes The Center's staff to additional techniques and strengthens the overall knowledge of both groups. In addition, interactions between the limited number of specialists who provide visualization expertise on a day-to-day basis and who are equipped with extensive hardware and software facilities accelerates the advancement of scientific visualization as a science. Research and development projects assure that the staff continues to be exposed to the latest data interpretation technologies and techniques. Most of The Center's research and development effort is directed towards extending the data interpretation capabilities available to WES researchers. However, The Center staff is encouraged to direct a portion of their energy towards independent research projects as a compliment to their service oriented tasks.
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Service activities reflect the commitment of The Center to assist with the more mundane, yet vital, tasks related to visualization. Such activities as: • providing assistance with both hardware and software that is available via The Center, • serving as the repository for public domain software, • evaluating existing standards and suggesting a set of standards that produce a managable working environment, • providing expertise in evaluating new visualization techniques and technologies, and • providing the interface between the researcher and the scientific illustrators available via The Center, are representative of the types of day-to-day requests and initiatives that roundout The Center's activities. These "real world" diversions prevent The Center from becoming detached from the daily requirements of the researcher. The Center is, therefore, forced to focus on actual issues rather than "hypothesized" demands. 3. FACILITIES Establishing a premier visualization center requires a sizable investment in both human expertise, visualization hardware/software, and video production hardware. The lack of sufficient investment in any of these critical items will tremendously restrict the ability to offer the visualization solutions required to support a mature research community. The WES SVC represents a multimillion dollar investment in hardware, software, and people. The success of such an effort is completely dependent on a commitment from senior management. The requirement to interact with a diverse set of researchers mandates that staff members in the visualization center be capable of communicating effectively in numerous technical subjects. Visualization, itself, is a multidisciplinary science and exercises skills in such fields as computer graphics, video, physics, engineering, numerical methods, art, and cognition. The selection of an interdisciplinarystaff should be regarded as the most important aspect of supporting any visualization effort. The Center's staffincludes individuals with graduate degrees in computer science, civil engineering, chemical engineering, engineering mechanics, and computer engineering. Additional staff members are experts in video production and scientific illustration. The hardware diagrammed in Fig. 3 represents workstations, peripherals, networks, and mass storage equipment located in The Center. The requirement for specialized 3-D visualization workstations is obvious. The majority of the workstations are from Silicon Graphics, Inc. However, The Center also utilizes an Apple Macintosh, a Sun workstation, and several staff members have IBM / RS6000 and Next workstations. The Center supports several output devices that may be considered prohibitively expensive for the individual researcher. A Canon CLC 500 color copier serves as both an output device and a color scanner. A Solitare 8xp provides both 35 mm and 4 × 5 film
LouIs H. TURCOTTE and BRADLEYM. COMES
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Seientifie Visualization Center
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Fig. 3. Visualization hardware. output for high quality reproduction and presentations. A Tektronix Phaser III printer provides high quality color postscript output. A standard laser printer, high speed dot matrix printer, and a Tektronix 4693DX serve traditional output requirements. An Abekas A60 real time disk system provides the link between the computer generated images and the video production facility. All of these devices are attached to a private ethernet. Figure 4 summarizes the broadcast quality video production facility. The nature of both the civilian and military research performed by the WES mandates that high quality video production methods be used to meet standards that are necessary for use in public policy forums. The critical link between the computational hardware and the video hardware is provided by an
Abekas A60 real time disk system. This system holds approximately 30 seconds of animation (at 30 frames/ second). Video frames residing on the A60 may subsequently be transferred to either analog or digital video tape at operator selectable speeds. As indicated by Fig. 4, the video production capabilities include all the components found in any commercial video production studio. Effectively delivering visualization solutions as part of a day-to-day routine creates ancillary technical challenges. The massive amounts of data being generated and analyzed by a supercomputer and subsequently needed for visualization can saturate network bandwidth. The Center has a dedicated FDDI link to the local CRAY supercomputer. As indicated by Fig. 3, the FDDI link has two access paths to The Center.
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Deliveringdata interpretation A separate FDDI connection is provided to a SGI file server that manages the disk farm used by The Center. This connection is used to migrate large quantities of data from the supercomputer to The Center. All other network traffic from The Center to outside networks is routed through a separately attached NSC FE640 router. This network topology has satisfied many of the data movement problems that typify visualization. The Center, however, plans to replace the internal ethernet with a private FDDI network. The second mandatory hardware requirement results from needing enormous volumes of disk space to support visualization, specifically animation. A simple calculation serves to validate the disk requirements. A 24-bit megapixel display requires about 2 MBytes to store a single frame of information. Video animation requires 30 frames/ second. Therefore, a 30 second computer animation can require as much as 2 GBytes of data storage. Presently, The Center has approximately 20 GBytes of online disk and plans to acquire a 100 GByte optical disk farm. The last critical component of a visualization center is the availability of software solutions. The initial goal of The Center was to provide rapid adaptation of visualization within the WES research community. This goal created a requirement to provide off-the-shelf solutions that could be implemented rapidly. The strategy was to acquire commercial software and freely available software. The Center's library of commercial software includes MPGS from CRAY Research, Interactive Volume Modeler from Dynamic Graphics, Wavefront's Advanced Visualizer and Data Visualizer, Bechtel's Walkthru, PV-Wave from Precision Visuals, and Unigraph from Uniras. Freely available software includes Khoros from the University of New Mexico, P3D from the Pittsburg Supercomputing Center, several programs from NCSA, lmagetools from the San Diego Supercomputer Center, and Exvis from the University of Massachusetts at Lowell. NASA developed tools include FAST and PLOT3D. These software solutions have been augmented by internally developed software for problems that are not readily solved using commercial software. The use of commercial and freely available software is not a panacea. "'Canned" solutions will usually require unique techniques to address the individual needs of the researcher. Additionally, the choice of software and the complexity of these multipurpose solutions may prove to be an obstacle for the researcher. The visualization expert's role is to help with the selection of the appropriate software tool and to teach the researcher how to use the tool most effectively for their problem. The use of"canned" solutions, when appropriate, minimizes the long-term support requirements for The Center and allows the staffto address problems that do not have off-the-shelf solutions.
4. APPLICATION EXPERIENCES Experience accumulated from numerous collaborative projects has confirmed the axiom that there is
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no single approach or solution that serves every need. The applications surveyed here represent a smorgasbord of approaches. Experience has proven that there are many facets of visualization that can only be developed from experience. The appropriate choice of colors and text fonts that transfer to video is one example. The use of format translators to move data between various software products and to video equipment is another example. These skills are difficult to summarize but play an important part in the overall efficiency and quality of the visualization product. Several visualization projects completed using commercial, public domain, and internally developed software are summarized. Visualization from CADD models, numerically generated scientific data, field data acquisitions, and artistic representations are presented. Figure 5a depicts the numerical results from a 3-D water quality model of the Chesapeake Bay. The water quality investigation required evaluating the behavior of over 20 different parameters (dissolved oxygen, salinity, chlorophyll, diatoms, etc. ). This frame shows the dissolved oxygen concentrations for a specific time during a one year simulation. Red regions signify zones with zero dissolved oxygen. The bay is approximately 200 miles long with an average channel depth of 75 feet. Therefore, the visual model has been dimensionally distorted. The widths of the tributaries were distorted to be visually discernable and the depth has been exaggerated. These dimensional distortions are characteristic of data sets that represent real world models. This visualization was produced using results from a 3-D finite difference model of the bay and the Interactive Volume Modeler software from Dynamic Graphics, Inc. Visualization of data produced by the water quality model of the bay will be used to assist with the evaluation of the effectiveness of nutrient reduction strategies to improve the water quality in the bay. Figure 5b is a frame from a 3-D animation depicting the salinity distribution in the Galveston Bay induced by daily tidal cycles. This frame illustrates the output from a software tool that utilizes distributed computing. The frame was generated using MPGS from CRAY Research, Inc. MPGS is a visualization tool that provides an interactive CRAY-SGI distributed data exploration environment. Results from the 3-D finite element model of the bay can he studied interactively to improve the accuracy of the model and provide more insight into the physical processes being modeled. This model is being used to study the effects channel dredging will have on oyster beds in the bay. Figure 5c is a frame from a 2-D animation produced from a time dependent study of a section of the lower Mississippi River. This frame depicts the river's bed elevation at one instance in time. The visualization software/tool was internally developed and is representative of the occasional problem that has no commercial visualization solution. This model is being used to evaluate potential options that will reduce maintenance dredging for deep draft navigation. Alternate placements of submerged dikes were rapidly evaluated
LouIs H. TURCOTTEand BRADLEYM. COMES
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to determine their effectiveness towards controlling sediment movement in the river. Figure 5d was produced using a NASA developed CFD visualization tool named FAST. This 2-D frame depicts the affects induced by a series of wells on the unconfined flow of groundwater in a river influenced aquifer near a slurry trench. The application of a visualization tool designed for studies in aerodynamics to studies in groundwater modeling demonstrates the potential benefits of cooperative projects between visualization groups. Figure 5e was generated using a visualization tool available to the public at no charge. Using software developed by NCSA, researchers are visualizing the affects of an accidental explosion within an underground munitions storage tunnel. This 2-D frame shows the temperature waves propagating within the tunnel for one instance during the simulation. Figure 5f represents the level of contaminant measured from a leaking underground storage tank. This 3-D visualization, produced using Interactive Volume Modeler from Dynamic Graphics, is use to determine site characteristics for numerical model calibration, scenerio analysis, and subsequent clean up and treatment of hazardous materials. Shown in the frame are computer interpolated contours created from actual field data. When using field collected data, visualization experts must be careful to verify that the final representation is more than visually pleasing. Numerous sensitivity studies were performed prior to accepting the results depicted by this frame. The capability of sophisticated software to display information rapidly should not distract practitioners of visualization from verifying that the information is scientifically accurate. Figure 5g depicts a 3-D CADD model developed for a proposed military housing facility. The use of CADD walk-throughs and fly-arounds represent another use of visualization. Visual animations of proposed construction projects can be used to refine and improve the construction sequences, thus producing significant cost savings. This animation was produced using Bechtel's Walkthru software. Figure 5h is a frame from an animation used to describe a complex beach erosion/wave testing sequence. The frame shown depicts the physical location of test sensors within a physical wave tank. Created by a scientific illustrator, this type of visualization has become a very effective method for communicating complex processes/events. Using Wavefront's Advanced Visualizer software, the illustrator used photos and design plans to recreate the layout of the test facility. 5. RESEARCH
The rapid growth in size and complexity of numerical models being employed will continue to challenge existing interpretation methods. Considerable research and development efforts must be directed towards resolving these interpretation impediments. The rate at which a researcher can consume information visually will eventually hinder productivity. Already, research
is being conducted in topics such as virtual reality, multi-sensory environments, auditorialization, cognitive issues, intelligent systems, and voice recognition. The integration of additional human senses such as hearing and feeling with vision will no doubt create a richer interpretation experience in the future. The use of virtual reality for experiencing three-dimensional data sets has received considerable attention in the last 2 years. Virtual reality systems combine stereo viewing display technologies with spacial location sensors to produce the simulation of a "virtual" world. The Center's efforts have been directed at two different hardware configurations. One system combines the Eyephone and Datagiove manufactured by VPL. The second system is manufactured by Fake Space Labs and combines a "BOOM" (Binocular Omni-Orientation Monitor) with the VPL Dataglove. The Eyephone system supports color, albeit at a very crude resolution (360 × 240). The BOOM system is black and white but provides higher resolution (720 X 486 ). Initial observations indicate that the color system offers an attractive technology for such applications as building walkthroughs and games. The BOOM system has greater potential for scientific data interpretation. The high resolution combined with the more ergonomically appealing viewing apparatus has been much better accepted and is more reliable than the helmet-based Eyephone system. The realization that teams of scientists involved in coordinated research projects will be distributed geographically provides a clue to one potential use of virtual reality. Collaborating researchers on opposite sides of the country, or world, will be able to "share" the data interpretation experience. Researchers connected via long haul networks will be simultaneously emerged in the same volume of data and will be able to more effectively communicate their premonitions with colleagues. They will be able to see the other person (a computer generated representation of the other person) looking and pointing at the data! Another research project, also in the initial phases, is attempting to demonstrate the benefits of augmenting the visual interpretation process with sound. This research effort is investigating the use of audio as an additional sense queue for interpreting complex numerical data sets. As data sets continue to increase in size and complexity, the use of additional human senses to augment the visual data representation will become of greater necessity. Correlating sound with the speed of a fluid or the magnetic forces surrounding an atom are a couple of potential uses for audio. The need for methods that provide effective interpretation of multiparametric data sets continues to challenge the present technology. The requirement to correlate and understand the complex relationships between as many as 20 constituents in water quality models continues to challenge us. The ability to provide real time animation at the desktop is another capability that is presently limited. These are but a few of the challenges that confront the widespread adaptation and implementation of visualization technologies. As these
Delivering data interpretation
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i
Fig. 5a. Cheml~ke Bay. Fig. 5d. Groundwater flow near series of wells.
Fig. 5b. Galveston Bay,
Fig. 5e. Accidental explosion in Munitions Tunnel.
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LouIs H. TURCOTTEand BRADLEYM. COMES entertainment characteristic, or as Walt Disney once noted: "I'd rather entertain people, and hope they learn, than try to teach people and hope they are entertained." 6. SUMMARY
The availability of a centralized visualization center has dramatically improved the capabilities of our researchers. Stallings [ 3] has summarized the use of visualization eloquently: "The videocassette is mighter than the viewgraph. A stunning image can have more impact than a long list of data, no matter how well researched."
Fig. 5g. CADD model of military housing facility.
The continuously expanding complexity of numerical models and the corresponding advances in raw computation power will mean that specialists in sophisticated data interpretation technologies will more frequently be included as integral parts of the research team. Transforming numerical calculations performed at G F L O P rates into scientific insight will require increasingly greater resources, both hardware and human.
Acknowledgements--The authors would like to acknowledge the contributions from the staffofthe Scientific Visualization Center and the individual researchers who provided input for this paper. The Army's High Performance Computing Research Center is operated by the University of Minnesota and funded by the Army Research Office, Contract Number DAAL03-89-C-0038. Permission was granted by the Chief of Engineers, U.S. Army Corps of Engineers, to publish this information. REFERENCES
Fig. 5h. Wave testing facility.
issues are identified and successfully addressed, more and more researchers will begin to realize the benefits from these radically new and different approaches to data interpretation. Consumption of these new tools will occur more rapidly when they possess an innate
1. B. H. McCormick, T. A. DeFanti, and M. D. Brown, Visualization in Scientific Computing. ProceedingsACM S1GGRAPH 21(6), p. 3. (1987). 2. Committee on Physical, Mathematical, and Engineering Sciences, Office of Science and Technology, Grand Chal-
lenges: High Performance Computing and Communications, pp. 5-7 (1992). 3. J. Stallings, Trends in Scientific Visualization: Is Beauty
Also Truth. Supercomputing Review, pp. 36-39. (August, 1990).