Tinkerers make data come alive on Google maps

SAN FRANCISCO — Tracking sexual predators in Florida. Guiding travelers to the cheapest gas nationwide. Pinpointing $1,500 studio apartments for rent in Manhattan.

Geeks, tinkerers and innovators are crashing the Google party, having discovered how to tinker with the search engine's mapping service to graphically illustrate vital information that might otherwise be ignored, overlooked or not perceived as clearly.

"It's such a beautiful way to look at what could be a dense amount of information," said Tara Calishain, editor of Research Buzz and co-author of "Google Hacks," a book that offers tips on how to get the most out of the Web's most popular search engine.

Yahoo and other sites also offer maps, but Google's 4-month-old mapping service is more easily accessible and manipulated by outsiders, the tinkerers say.

As it turns out, Google charts each point on its maps by latitude and longitude — that's how Google can produce driving directions to practically anywhere in the nation. Seasoned developers have figured out how to match these points with locations from outside databases that can contain vast amounts of information — anything from police blotters to real estate listings.

Thanks to Adrian Holovaty, 24, who overlaid Chicago Police Department crime statistics on a Google map, house-hunters in the Albany Park neighborhood can pinpoint all the sexual assaults in the district between May 19 and April 19 on a single map. With each crime marked by a virtual pushpin, Chicagoans can quickly learn what dangerous train stations, pool rooms and alleys to avoid.

Holovaty hopes to make the maps more current by persuading Chicago police to provide the data directly, rather than forcing him to glean it from the department's Web site. Police seem amenable — he's got a meeting with them next week. But community activist James Cappleman is already impressed with Holovaty's Chicagocrime.org — no longer do residents have to trust politicians crowing about safer streets.

"We've never been able to track trends before," Cappleman said. "Now, when we tell police there is a problem, we'll know what we're talking about."

Visitors who check out Floridasexualpredators.com, which combines Google Maps with data on convicted sex offenders, can call up maps of their communities and click on the pushpins to see the name, last known address and mug shot of each offender.

Drivers searching for their area's cheapest gas can go to www.ahding.com/cheapgas, which blends Google Maps with data from Gasbuddy.com's database of prices at individual gas stations.