Planning Cities in the Virtually Real World : Computer replicas of L.A. streets are building blocks for urban designers, right down to the tree trunks.

Bill Jepson has created a virtual world--and the world is Los Angeles.

He and co-workers at UCLA’s Graduate School of Architecture and Urban Planning have carefully recreated in their computers several L.A. neighborhoods, down to each and every building, street and design nuance. Sitting down at a terminal, a visitor to this faux L.A. can walk, drive or fly through this realistic--and eerily uncrowded--rendering.

“Remember, we experience our world in three dimensions,” said Jepson, the graduate school’s director of computing. “This is exactly what we’re used to seeing.”

This is no computer game, but rather a new tool for those involved in building the city of the near future.

For planners and architects, the City Simulator can be even better than the real thing. With a mouse click, they can discard burned-out ruins, insert new building facades, add a sidewalk--basically, play with their ideas and see what results.

How would the neighborhood look with trees lining its streets? Here’s a few sycamores. How would a new office building transform the surrounding area? The computer can lay it in, and show its effect on traffic and shadows.

In the future, the system may also help speed firefighters to a blaze and help historians recreate how ancient ruins looked in their heyday.

Architects have long created wood and plaster models of their designs, but these only provide a Gulliver-in-Lilliput vantage point. “With a wooden model, you’re always looking from a helicopter-like perspective,” Jepson said.

Computer-generated images aren’t new either; movie special effects can now meticulously create almost any scene. However, these effects often take weeks of computer time to generate and show only what the animator wants the viewer to see.

This kind of virtual reality opens the door to exploration. In City Simulator, if you want to take a look down Vermont Avenue and point the mouse in that direction, the scene instantly appears before your eyes. Adding to the detail, pedestrians saunter down the sidewalks, police cars roll by and an airplane zooms above.

“It advances your perception,” said James Amis, senior manager of joint development at the Metropolitan Transportation Authority. Jepson modeled for the MTA an office and shopping complex proposed to rise on top of the soon-to-open Wilshire subway station.

On Jepson’s computers, even untrained eyes can quickly spot potential problems with proposed buildings.

In the early design of the Wilshire project, sheer vertical walls abutted the sidewalks, creating a fortress-like presence. The architects have since moved back the walls of the lower floors.

“It’s a helpful tool to see things quicker,” Amis said. “It gives you more visual interaction. It shows three-dimensionality. You could move through the project. You can actually see it.”

Jepson achieves this swift magic through state-of-the-art graphics computers and a shortcut.

Rather than create meticulous models that take large amounts of number crunching, Jepson instead sent his students to photograph each building from each side. The photographs, scanned into the computer, were then wrapped around simple, box-like models.

“It’s more realistic and it’s much quicker,” Jepson said.

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When Jepson showed a comprehensive model of the Pico-Union district recently to a group of community leaders, he wanted to illustrate one possibility for softening the neighborhood’s sometime stark landscape. His proposal: Require that each time a property changed hands, a tree be planted along the street.

“The entire character of a neighborhood changes depending on the street tree,” Jepson said. “Most people are really amazed how dramatic that change is.”

But as streetside pistachio trees popped onto the screen, Jepson heard behind him not praise but grumbling.

“Finally I asked, ‘What was the complaint?’ ” Jepson said. The Pico-Union delegation explained that gang members often hide in trees and jump down on unsuspecting passersby. The street trees would only make things worse.

“We weren’t solving their problem, we were solving our problem,” Jepson said. “We didn’t understand their problems.”

With a couple more clicks of the mouse, Jepson changed the pistachio trees to towering palms. The group applauded. “That’s great,” one observer said. “If they jump out of those trees, they’ll break their necks.”

Next on the agenda is tying various databases into the system. Planners would be able to immediately pull up the address, assessed value and other information about properties. Clicking on the traffic lights, for example, could be programmed to display information about traffic flow.

For fire department dispatchers who may someday use a similar system, a fire alarm could trigger animated flames in buildings.

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Dispatchers would be able to better describe to firefighters the surrounding area--for instance, that there’s a chemical factory down the street or a hospital next door. “Before they get the fire, they’ll know exactly where to go,” Jepson said.

Through small radio transmitters sending signals to satellites orbiting the Earth, the system could also keep track of the location of each ambulance, firetruck and police car.

On a more recreational level, Jepson envisions the virtual reality world as an entertainment guide. For example, clicking on the virtual version of a Sunset Boulevard club could play a snippet of music. “You’ll be able to stick your head in the theater by your house and check out the band,” he said.

With a few tweaks, the system opens doors to the past as well as the future.

In a project with the J. Paul Getty Museum in Malibu, one of Jepson’s graduate students, Dean Abernathy, is recreating the Trajan Forum--what essentially was a shopping mall in ancient Rome.

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After getting an undergraduate degree in architecture, Abernathy spent a year in Italy, where he learned that what he saw in real life was very different from what he was taught in class.

“There was a huge gap between the traditional methods of teaching architecture and being able to experience the space,” Abernathy said. Photographs and models, he said, could not capture the building’s size, the surrounding space or the subtle effects of lighting.

With City Simulator, Abernathy and Jepson hope, historians will have a better sense of what the ancient Romans experienced. “We can have Cicero come out on the steps and give his speech as we’re walking around the Roman Forum,” Jepson said.

For museum visitors, that could transform artifacts into more than objects in glass cases. “I think one of the things that is missing is an easy way to help the public understand what the context was,” said Kenneth Hamma, associate curator for antiquities at Getty Museum.

“This is certainly one way of doing it.”