Computer Graphics World

December 2008 20 ■ ■ ■ ■ Virtual Architecture would change and evolve—thus showing that all roads do not lead to Rome, at least not the one Frischer envisioned. In the mid-'80s, Apple Computer al- most sponsored the creation of a videodisc containing imagery of the monument. e plan called for Frischer and his group to maneuver a tiny robotic camera through the physical model. However, the model lacked a certain amount of detail. " e doors, windows, and columns had detail- ing around the edges and included all the parts, but most of the walls and surfaces were plain," recalls Frischer. "As you go down a street and look at the facades, you see non-diff erentiated white plaster. It just didn't look like a street." at was because of a POV issue. Like today's digital modelers, the physical mod- el makers had taken shortcuts by adding detail only to the areas that would be vis- ible—in this case, from the viewing area above. Because of the disappointing results, the disc was not made. But for Frischer and his group, the revelation was a turning point. "I realized that if we wanted to make a digital model of Rome, we'd have to start over from scratch," he says. A few years later, Frischer consulted on an exhibition that integrated works of art from an ancient site into a 3D reconstruc- tion. Identifying an opportunity, Frischer suggested the Forum of Trajan in Rome. "We placed the remains of the forum into a gallery and then projected a 3D model of how it actually looked onto a screen," he ex- plains. is introduced Frischer to real-time 3D modeling software, in this case, Creator from MultiGen-Paradigm (now owned by Presagis). Unlike other 3D content-creation software, such as Autodesk's Maya, Creator allows the modeler to input exact architec- tural measurements—a valuable building block for digitally re-creating Rome. Confi dent that he was now heading in the right direction, Frischer consulted with Bill Jepson, whose Urban Simulation Lab at UCLA was devoted to making a large city model of contemporary Los Angeles. "Bill had the right lab, with the right hard- ware and software, and the right know-how to make a model of any kind of city—con- temporary or historical," says Frischer, who eventually set up his UCLA Cultural Vir- tual Reality Lab in 1996. 'Empirical' Modeling And with that, ancient Rome was on its way to being digitally reborn, though the eff ort would prove to be no Roman holiday. e team's approach was to start at the city cen- ter—the Roman Forum—and work out- ward in concentric circles to the city walls. "To make this a high-quality work, we had to get peer contributions from scholars who have spent years studying ancient Rome," Frischer says. He points to what he and oth- ers consider a not-so-successful re-creation of Pompeii in the 1990s by Carnegie Mellon's Sim Lab: e group had the proper equip- ment but didn't work in conjunction with archaeologists, and while the model looked great, it lacked authenticity. "We decided the archaeologists should run the show, and the technologists would be at the service of the archaeologists," Frischer adds. "As it turned out, many of the technologists were young scholars, spending their summers studying archae- ology and conducting fi eld work." Construction began on the Roman Fo- rum and the Colosseum, as the modelers crafted the building using Creator. For rendering the textures, they used a radios- ity-based method of baking in the lighting solution. e models looked high quality for the time, but they appeared to be fl oat- ing in space, with no context. "We decided to build up some context with an elevation map and fi ller architecture in the land- scape, to make the two structures look like part of the urban fabric," says Frischer. is brought Frischer back to the Plastico di Roma Antica model. Professor Gabriele Guidi from Milan headed a team that digi- tally scanned the monument. Ideally, they would have placed laser scanners or photo- grammetry equipment on top of the physi- cal model. Because that was prohibited, the crew had to conduct the scan from the bal- cony of the room. While the resulting mesh was accurate in terms of reverse engineering, it was not appropriate for VR applications because of the subtle distortions in the ge- ometry, resulting from an interaction of the noise from the scan process and the scale of the physical model—any error was multi- plied by 250, the scale factor. "When you looked at the results up close, they were terribly distorted and warped," The team is in the process of upgrading the models in Rome Reborn 2.0 with geometric detail as opposed to baked-in textures. Each model will average approximately 10,000 polygons.

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