"Cities in the U.S. are perfect for doing pixel drawing," he says, "which is what I'm drawn to anyway. In Spain or Japan, there's a whole web of streets that are completely chaotic. If I were doing GPS art over there, the forms I'd be making would be much more organic."
"I had a 'Eureka!' moment and realized that if I could draw that," he says, "I could draw anything."
His new project meshed with his personality, which is naturally upbeat and which seeks out opportunities for creative self-expression.
He's constantly inventing new words and phrases (a dead rat is a "Charm City super-flatty") and his Halloween costumes are legendary among his group of friends. Wallace is especially proud of his "Frozen Han Solo" of "Star Wars" fame.
At the private school where Wallace teaches (his employer asked him not to identify it), he says jokingly that he has his own museum: The Wallysonian. It's a bookcase filled with examples from his two other spare-time passions: astronomy, and collecting meteorites.
"Instead of driving a luxury car," he says, "I own a $30,000 rock collection."
Each summer, Wallace completes between 40 and 45 rides. The longest cover nearly two dozen miles and take up to four hours to complete. He begins by looking at a photocopied street map and brainstorms while watching television.
"I look deep into the streets," he says, "and see what pops out."
Once he has mapped out a tentative route, he views satellite photographs of the area on his computer to identify potential impediments, such as a construction site or blind alley. When Wallace can work around an obstacle, he will. He has climbed steep embankments, hoisted his bike over brick walls and cycled through the tennis courts at Patterson Park.
"I'll slide my phone through a hole in the fence and then ride around to the other side and pick it up," he says.
A few drawings — a gun, a syringe -— have political or social messages, inspired by some of Baltimore's grittier vistas. But many more unabashedly celebrate city life, from Opening Day at Camden Yards to the recent Sailabration.
Hoffberger is charmed by Wallace's drawings and finds in them evidence of the artist's idealism.
"It's interesting what vocabulary he chooses to focus on," she says. "There are all these noble, iconic kind of figures, quixotic knights, and centaurs and griffins."
On and on Wallace pedals, from Mount Vernon to Highlandtown, connecting all the dots.
He's busy planning what may be his magnum opus, a drawing of the world he'll call "Continental Drift." When he has finished it, every land mass and ocean will be drawn by the same, continuous black line.
"I've found a way to fit the entire world into Baltimore," he says.
GPS art sites
Gearing up to make your own GPS art? Check out these drawings:
Michael Wallace, wallygpx.com
Jeremy Wood, jeremywood.net and gspdrawing.com
Vicente Montelongo at http://mexist.com