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    SDSC TeleManufacturing Facility: Solid Results, Tangible Benefits

    FEATURED
    Michael J. Bailey, SDSC and UC San Diego

    The SDSC TeleManufacturing Facility (TMF) gives researchers anywhere in the nation a way to produce solid models for scientific and engineering visualization. Like a 3-D printer, the TMF uses geometry files submitted via the Internet to build scale models of objects ranging from molecules to entire planets. The TMF has even built mathematical shapes and hard-to-imagine characteristics of systems. The TMF has created models for researchers in mathematics, planetary science, medicine, oceanography, biochemistry, atmospheric science, and other fields.

    "Just about every time people build a TMF model, they see something they missed in the computer graphics rendering," said Mike Bailey, SDSC senior principal scientist, UCSD associate professor, and leader of the TMF project. "Computer graphics images and animations and even virtual reality simulations can't convey all the information that real objects do."

    The TMF comprises a Sun workstation and a PC-controlled Helisys Laminated Object Manufacturing (LOM) machine. The LOM uses a computer-controlled laser to cut layers of paper--250 sheets per inch--that are bonded together to form solid objects. The resulting models look and feel like wood. The LOM was designed for rapid prototyping of mechanical parts, and in the TMF, Bailey was among the first to use it for serious scientific visualization.

    "The TMF is more than a manufacturing machine," Bailey explained. "It incorporates custom software for automatic translation of geometry files, automatic detection and correction of geometry errors, and remote monitoring." Users can submit geometry files to the LOM via the Internet, and can monitor the progress of their models on the TMF Web page.

    BUILDING WORLDS

    MOLECULAR ARCHITECTURES

    VISUALIZING THE UNSEEABLE


    Figure 1. US terrain map.Figure 1. American Terrain
    This 3-D terrain map of the contiguous United States is now in the U.S. Library of Congress.
    Figure 2. Two views of TMF globe.Figure 2. TMF Earth
    The globe model is 7.6 inches in diameter at sea level, with the Earth's elevation range of 8.79 miles below sea level to 5.95 miles above mapped into 1.5 inches of relief. (Photo by Dave Teel)

     


    BUILDING WORLDS

    In December 1998, Bailey created a topographic model of the continental United States for the U.S. Library of Congress (Figure 1). The new model was tiled together from four separate blocks produced on the LOM. It spans 24 inches east-to-west, 18 inches north-to-south, and varies 2.75 inches in elevation.

    Calling the LOM model "an important addition to the cartographic collections of the Library of Congress," Jim Flatness of the library's Maps Division said the model "helps us depict and document new computer-assisted techniques of cartographic production." The model is now on display in the Geography and Map Division Reading Room, but this spring it is scheduled to be displayed in "American Treasures of the Library of Congress," the Library's major exhibition.

    In 1997, Bailey tackled an even larger subject. He and Sheldon Applegate of Litton/TASC constructed a relief map of the entire world. Dissatisfied with the distortions of the flat map, Bailey then built a globe the size of a bowling ball, with the vertical relief of the land and seafloor topography exaggerated for effect (Figure 2). The model weighs nine pounds and took 51 hours to construct.

    Having constructed this world, Bailey received a request in January from scientists at Cornell University to build an out-of-this-world model. A month earlier, NASA's Near Earth Asteroid Rendezvous (NEAR) spacecraft had flown past asteroid Eros. NEAR photographed the asteroid and sent a sequence of images back to Earth. From the images, the NEAR imaging team at Cornell made a 3-D map database of the 20-mile-long Eros, but the database creators at Cornell's Spacecraft Imaging Facility felt they could understand a physical model better than they could a map or an image on a computer screen.

    Cornell's Brian Carcich contacted Bailey and sent a geometry definition file for the asteroid to determine whether making a LOM model would be feasible. Bailey fed the geometry definition file to the LOM's computer, and about eight hours later had a model of Eros. Expecting a long negotiation and model-building process, the Cornell team was pleased to be holding the model only a few days later (Figure 3).

    "Thanks! This is cool!" Carcich e-mailed to Bailey. The Cornell team intends to build more accurate models as more detailed information becomes available when NEAR encounters and goes into orbit around Eros next year. Bailey is looking forward to working with the Cornell space scientists. "This was a fun one to make," he said. "People can really get a sense of the 3-D form of this thing."

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    Figure 3a. Photo and geometry of Eros.Figure 3b. TMF model of Eros.

    Figure 3. Eros, by NEAR and by LOM
    Scientists at Cornell University used photos of the asteroid Eros taken by the NEAR spacecraft (left), together with trajectory and orientation data, to map the geometry of the asteroid. The LOM model (right) and the graphical renditions both resulted from this geometry file. (Photo by NEAR Project, JHUAPL, Cornell, JPL, NASA)

     


    MOLECULAR ARCHITECTURES

    Jay Siegel, professor of chemistry at UCSD, is a molecular architect who has helped reshape the fields of molecular design, structural analysis, and chemical synthesis. "It's amazing what you can control on the molecular level," he said. "You have atoms bouncing about erratically, and yet with the right chemical technology you can coax them to adopt very specific molecular shapes, arrangements, and attachments."

    Siegel has been preparing what he calls "molecular rebar"--frameworks that can be modified by "spot welding" them together to form grids, ladders, and more complicated structures. Recently, he designed and synthesized a matrix resembling a tic-tac-toe grid from phenanthroline molecules connected by strategically placed metal atoms. SDSC computational chemist Kim Baldridge has been working with Bailey and Siegel to model this molecule and its properties through computer graphics and the TMF (Figure 4). "The spacing in the grid is perfectly arranged to allow flat molecules to insert themselves between the grid elements," Siegel said. He believes that constructions of this type may find applications as "tuned" sensors for specific molecules.

    Baldridge and Siegel also have been investigating and modeling molecules in the fullerene family--spherical buckyballs, cylindrical buckytubes, and hemispherical buckybowls. Although similar in pattern, the various molecules have different chemical properties. The researchers are particularly interested in the buckybowl molecule corannulene (C20H10) and its relatives with 30, 40, and 50 carbon atoms. These other compounds have not yet been synthesized, so Siegel and Baldridge are modeling them with ab initio computational chemistry methods on SDSC's supercomputers. The LOM models of buckybowls have assisted the chemists in their analyses.

    "The qualitative and quantitative computational models we develop allow the experimentalists to preview the structures they are planning to make," Baldridge said. "These cutting edge molecular architectures challenge us to develop more reliable and user-friendly models and interfaces."

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    Figure 4. TMF model of tic-tac-toe moleculeFigure 4. The Tic-tac-toe Molecule
    This matrix resembling a tic-tac-toe grid (right) is formed from from four phenanthroline molecules (left) spot-welded together by strategically placed metal atoms.

     


    VISUALIZING THE UNSEEABLE

    Rich Charles, an associate staff scientist at SDSC, has been investigating display techniques for fluid flow in two dimensions. In addition to quantities such as density, pressure, or vorticity, which have only magnitude, fluid flow displays need to indicate vector quantities such as velocity, which have both magnitude and direction. Traditionally, arrows indicate vectors by their directions and lengths, but this shows the quantity only at certain spots rather than as a continuous field. An alternative is to use color (hue) and intensity to represent velocity vector fields; however, human shape perception ignores colors, making it difficult to detect structure in the flow.

    At the January 1999 Aerospace Sciences meeting of the American Institute of Aeronautics and Astronautics, Charles presented a paper on ways to use the third dimension--treating the 2-D fluid as a rippled surface, with height above a flat reference plane representing one of the components of a vector field such as its magnitude. In a diagram on paper or on screen, this can be indicated by an oblique or perspective view of the surface.

    To fully appreciate the shape in three dimensions, Charles and Bailey created a LOM model of a fluid jet that corresponds to the false-height velocity plot (Figure 5). The LOM model isn't colored, so this shows only the fluid speed--but it shows it in detail. "To show the same information as Rich's plots, we'd have to paint this model," Bailey said. "Perhaps there's a photographic technique or ink-jet printer technology we could adapt to this, some automated process to ensure the color and intensity values were accurate."

    "I have always thought that one of the really great things about scientific visualization is that there are no rules or limits on what you can do," Bailey continued. "Everything comes into play. Any way to move information from the brain of a computer to the brain of a human is fair game." --MG

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    Figure 5a. False-height image of flow.Figure 3b. TMF model of false-height representation

    Figure 5. Visualizing a Jet of Fluid
    Rich Charles illustrated his display technique using a jet imbedded in a co-flowing stream. The velocity field of the jet is displayed using a false-height representation for speed and color for direction (top), and a LOM model displays fluid speed as the height of the model (bottom).

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