One recent sunny Saturday afternoon, two inventors talked their way onto the roof of a downtown condo tower. They chose the tower because, magically, it's mostly free of view-blocking neighbors; you can almost shoot a full-360 photo of the city from up there. They set up a modified camera and went to work, taking thousands of pictures in every direction, which later would be combined to create one incredible image stitching them all together. In this new superimage, you can see who's on the viewing deck at the Space Needle in the center of the city, as well as if there's a climber halfway up Mount Rainier 82 miles away. Made of many billions of pixels, this superpicture is probably the single most detailed image ever captured of Seattle.

It's not for state surveillance. Its purpose is art.

"A small team at Microsoft Research has pioneered the technology behind the creation of very-high-resolution panoramic images that allow you to pan and zoom to very fine detail. Now the team wants to create a celebration of the arts in Seattle," John Boylan wrote in an e-mail to his extensive address book full of artists. Boylan's been organizing public conversations about art in Seattle for more than a decade. He knows the Microsoft inventors of Photosynth—Michael Cohen and Matt Uyttendaele, the two guys on the roof of the condo—and he's helping them with the project they're calling Gigapixel ArtZoom.

"This will be a single, multibillion-pixel, zoomable panoramic image of the city and its surroundings," Boylan wrote. "Imagine yourself somewhere in the image. Cohen and his team want to create a sweeping image of Seattle where, when you drill down, you will see performers and artists on street corners, on rooftops, in parking garages."

Dancers in midair, muralists in mid-mural, writers on boats out in Elliott Bay.

Many artists are signed on already, and more are welcome (e-mail Elise Ballard at elise.ballard@hotmail.com). Each arranges an appointment in a specific location. The camera will be stationed on that rooftop at Broad and Second to replicate the perspective of the original superpicture created that sunny Saturday afternoon, which will provide the backdrop for the final portrait. At appointed moments, through text-message coordination, the artists will begin doing their things and the camera will start shooting.

Later in the studio, one image of each artist will be selected. These images will be cut out and stitched into the original superpicture, superimposed onto the lawns at Gas Works Park or the waters of Lake Union (places that just happened to be empty of people on that original Saturday).

The final media object, the interactive Gigapixel ArtZoom itself, will be made publicly available online when it's finished. Its creators hope it will become a historical document, maybe even kept in the digital collection of the Museum of History and Industry as a portrait of Seattle art in fall 2013, all visualized to be happening at the same moment.

The organizers are working to beat the winter weather and juggling the elaborate management of hundreds of artists performing exactly at their appointed times across the city—and then, hours and hours of postproduction work will go into finishing the Gigapixel ArtZoom, which organizers are dreaming of unveiling publicly on the giant panoramic screen at Pacific Science Center sometime before the end of the year.

Shooting started this week. If you see an artist out there performing for nobody, it doesn't mean nobody's watching.