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Giant Robot Arm Creates 3D Light Paintings

When it comes to light painting, the designs are often less impressive than the effect itself: glowing, electric shapes suspended in midair that can only be seen with the aid of a camera lens. Many artists have spent a painstaking amount of energy trying to nail the technique, but ultimately the lack of visual feedback (and lack of precision) makes it difficult to see what you're creating in real time. It would take a robot or a machine to be able to craft crisp illustrations or even portraits through long exposure shooting. And that's exactly what a group of students at Carnegie Mellon University are using to create industrial light portraits: a massive robot, typically used for heavy-duty manufacturing, that paints with RGB LEDs as if it were a still-life expert. 

Jeff Crossman, a master's student studying human-computer interaction at Carnegie Mellon, and Kevyn McPhail—an undergraduate studying architecture with a focus on 3D-printing, laser cutters, and industrial robots—are collaborating with the university's Digital Fabrication Lab to make hi-fidelity, 3D light paintings of real people in depth and color, using a computer-controlled industrial arm, RGB LEDs, and a Kinect camera.

Unlike the shaky hand of your humanoid long-exposure enthusiast, the robot arm—an ABB-made IRB 6640 model—has hyper-accurate control of its movements, allowing the artists to create images within software programming that tells the machine what to paint.

"I always thought [light painting] was an interesting effect," said Crossman. "But all the piece I've ever seen were done by hand with lots of arcs and curves. Very trippy and abstract stuff. We wanted to make paintings that were as realistic as possible." McPhail echoed his thoughts, adding "Most projects involving light painting and robots seem to either do line drawings or single-color objects. We wanted to create full color portraits in 3D of real people."

To dive a bit deeper into how the project works, the system takes "point clouds" that are attained through Processing script and the Kinect camera, and then each point's color and depth data are sent to 3D-modeling program Rhino. The modeling program then incorporates algorithm-plugin Grasshopper and robot programming and control plugin HAL to command the arm how and where to move. The arm's tip is equipped with BlinkM LEDs, which get placed in midair through a Teensy microcontroller. McPhail noted that getting the robot and the light to synch up perfectly was the hardest part of the procedure.

Next, like any other light painting project, DSLR cameras capture long exposure shots—5,000 depth and color points garnered over 25 or so minutes:

The results are pretty incredible. Have you ever seen a light painting this detailed and textured? It would be near-impossible for a human to replicate the skill and accuracy of these machines. We could even imagine a future where robot arms light paint portraits of people on boardwalks or in museum galleries, thanks to this method. To create caricature-esque exaggerations, maybe certain PhotoShop tools could be added to the software. 

On the future of robot-lead light art, Crossman said, "Robots like this are expensive and are out of reach of most of the light painting community." At the same time, though, he noted, "I think [the project] shows the precision machines can deliver and how we can use them to supplement the shortcomings we have as humans." 

While the patience needed to create almost any light painting is laudable, we have to give it up to Crossman, McPhail, and their team for one-upping pretty much everyone in the long exposure game. Who knew manufacturing-robots could be so artistic? 

See some photos and GIFs of the final light paintings below, as well as a video detailing the project's process:

For more on this project visit Jeff Crossman's website here.

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