In his bid to find innovative ways to extend the artist’s reach to previously inaccessible spaces, KATSU, who is a member of the online free culture and technology collective F.A.T Lab, has projected his art out of the material world and into digital sphere. In 2013, he started placing his graffiti tags in the video game Minecraft. Indeed, he has even tagged an entirely imaginary space: in 2010, he created fake (but very realistic) videos of himself spray painting the White House (video below) and a Picasso. Briefly, many in the art world were fooled.

KATSU’s new project is not fake or hypothetical, though it does elevate his work to new heights. He has developed a system to attach a spray can to a quadcopter, creating the world’s first true graffiti drone. The drone is capable of spraying canvases or walls hundreds of feet tall, granting the artist access to physical spaces that were previously inaccessible. At the Silicon Valley Contemporary art fair, which opens April 10, KATSU will show a series of canvasses that he created with his graffiti drone...

Katsu, who gained graffiti fame in the 1990s in New York City, showed a series of paintings created by the flying machine at the Silicon Valley Contemporary art fair last weekend. The splotchy canvasses wouldn’t necessary stop you in your tracks, but the process by which they were created is entirely new. Katsu pilots the craft remotely, but every movement is translated through the machine’s need to keep itself aloft.

"To a large degree, it’s up to the drone. It’s like, I’m telling this device to basically accommodate this new attached payload that has an unusual shape, which then changes the drone’s shape. The drone is suddenly trying to adjust in real-time to the decreasing weight of the paint as the can empties. The flight patterns, the gestures, are my control. But it’s really strange–it’s weird, bizarre: it’s like 50 percent me having control and 50 percent the drone kind of like saying, ‘no I need to go this way’ or ‘I need to bounce out this way’ or ‘I need to turn this way to accomplish what you want me to do but still maintain myself so I don’t just fly into the wall and explode.’ Which it does, all the time; well, it’s doing it less and less now that I’m getting a better relationship with it."
(From Interview: KATSU and The Graffiti Drone)

This idea is to some extent presaged by the graffiti artists in William Gibson's 1999 novel All Tomorrow's Parties, who go to great lengths to tag the "untag gable" surface:

…Someone had once come up with a smart tag, a sort of decal they'd somehow adhered to the [smart] wall, although [they] had not been able to figure out how they'd done it without being seen. Maybe they'd shot it from a distance...
(Read more about Gibson's smart tag)

Graffiti artists could choose the opposite direction - go underground. In the enjoyable 1993 movie Demolition Man (with Sylvester Stallone, Wesley Snipes and Sandra Bullock), taggers create remote controlled underground drones:

Udpate: In the Judge Dredd comics, a graffiti war breaks out between disaffected teen Chopper and a mysterious artist named The Phantom, who turns out to be a bored city painting robot:

(The Phantom meets Chopper)

Thanks to Dave for pointing this out. End update.

The battle between street artists and those who'd prefer to have buildings and public structures remain as the architects intended rages on.