Classic Computer Magazine Archive COMPUTE! ISSUE 129 / MAY 1991 / PAGE 96

Your PC is your ticket to Mars. (fractal landscape simulation) (column)
by Steven Anzovin

Mars, the red planet, looms ahead. Flying at spacecraft speed above the orange and umber terrain, you swoop past awesome Martian landmarks. Ahead is the vast canyon of the Valles Marineris, 3000 miles long and more than 3000 feet deep. Towering above the Martian plains is Olympus Mons, the tallest volcano in the solar system. Its base is the size of Nebraska; its peak nearly juts out of the thin Martian atmosphere. Beyond are endless seas of red dust, alien fields of stone, dustings of carbon dioxide frost that evaporate at the first touch of the cold sun.

No, this isn't a scene from the 1950s science fiction film The Angry Red Planet. It's Mars: The Movie, an amazingly accurate virtual reality simulation of the Martian landscape created by NASA's Jet Propulsion Laboratory. The JPL used actual electronic images from the Viking Mars probes to create a two-minute simulated journey across a U.S.-sized area of the red planet, re-creating scenery that no one has ever actually seen. The concept of virtual reality simulation is not that difficult to understand in principle. The process turns dimensionless numerical data--for example, radar readings of elevations taken at set intervals on the surface of a planet-into an accurate 3-D representation. You could do pretty much the same thing by using a topographic map as a guide for modeling a mountain range out of clay, though a computer can do it faster and more accurately. The wizardry lies in making the simulation look real.

Lighting, shadows, colors, and the reflectivity of different kinds of surfaces-impact craters, soil, vegetation, bodies of water-have to be convincing. In Mars: The Movie, JPL used image enhancement techniques to bring out small details, smooth the edges of landscape features, and seamlessly stitch together the edges of adjoining maps. All this makes Mars: The Movie and its JPL siblings, including Miranda: The Movie (Miranda is a moon of Uranus) and Earth:

The Movie, too real not to believe. And believability is the true test of any simulation. (You can get a video copy of these and other simulations for $19.95 from Video Publishing Group, 5055 NW 159th Street, Miami, Florida 33014; 305-621-7283).

While virtual reality landscape simulations can be art in their own right, they are also useful for line-of-sight surveys, previews of large-scale civil and architectural engineering projects, environmental impact forecasting, exploration of exotic environments, and other applications involving sites too hazardous, difficult, or costly to visit in person. But suppose you simply wanted to make MY Town: The MOvie. Interestingly, you don't need a JPL supercomputer to do the j ob. In fact, all that's required is an Amiga 500 (one of the lowest-cost home computers around) and a program called Vista, from Virtual Reality Laboratories (2341 Ganador Court, San Luis Obispo, California 93401; 805-545-8515; $99.95). Like the big-time 3-D landscape simulation software, Vista can take 2-D elevation and contour data and convert it into a 3-D virtual reality that can be viewed from any angle. To make a fly-by movie, you move the viewpoint along a path and save pictures at set intervals to an animation program or VCR.

Vista can generate 4 billion fractal landscapes, but most people are using the program to simulate real places. Vista accepts the United States Geologic Survey's Digital Elevation Mapping (DEM) files, which currently cover about 40 percent of the country. A DEM file contains essentially the same information found in a USGS paper contour map, but in database form. Getting DEM data into Vista is not a task for the faint of heart. Once you've called the USGS to find out whether the area you're interested in has been digitally mapped, the Survey will send you (for a fee) an MS-DOS-formatted tape with the relevant DEM file. (How many of you have a tape drive at home?) Then you've got to convert it to an Amiga-readable format, which requires programming skills in C. If you take the time to master the file format, you don't have to limit yourself to USGS data-you can enter any topographic values you like. So, for example, you could create a 3-D map of your backyard, assuming you want to go out and measure all the bumps in the lawn. It doesn't have to be a landscape-one user has adapted Vista for molecular modeling. For nonprogrammers, Virtual Reality Labs is trying to make things easier by offering data disks with the most-requested DEM files, plus other goodies like 3-D projections of the latest Magellan probe maps of Venus.

Reality simulation in your own home-is it a more practical use of your time than balancing your checkbook? According to Susan Woeltjen, one of the developers of Vista, the U.S. military thinks it's practical. Apparently, the Department of Defense has been looking into Vista as an engine for cheap, fast simulations of Iraqi terrain. It's interesting to contemplate that the success of a multi-billion dollar military operation in the Middle East might just depend on the virtual reality created with a $600 computer and a $99 software package.