Tikalon Blog by Dev Gualtieri

Gaffer Drone

August 8, 2014

I'm one of the few people who actually reads the credits at the end of a movie or television show. Actually, I should write that I try to read the credits, since they usually scroll or flash very fast. In the industry, scrolling credits are called "the crawl." It's there that you find such colorful characters as "best boy" and "gaffer."

A gaffer is the chief electrician on a film or television crew. As such, he's responsible for the lighting. A best boy is his assistant, and his role is to manage the lighting crew. The etymology for "best boy" comes from the expression for a master's most experienced apprentice.

Proper lighting is essential to still photography as well as film making. It's easy to distinguish by the lighting whether a particular photograph on the Internet was shot by a professional, rather than an amateur. In my own photography, one thing that I check when posing people outdoors is patchy lighting. People posed under trees can have patches of light on their faces that ruin an otherwise good photo.

Acclaim Lightboard by Electronic Theatre Controls

High-tech lighting.

The control console of a computerized theater lighting system, manufactured by Electronic Theatre Controls.

(Via Wikimedia Commons.)

A big part of lighting is placing the lights in the right place, and that's the reason why there are so many names listed on a video production crawl. A team of computer scientists from MIT and Cornell University has updated the gaffer's craft by using spotlight-equipped autonomous drones for photographic lighting.[1-3]

These drones sense the positioning of the photographer and his subject to position themselves at the ideal lighting location for an effect called rim lighting. In rim lighting, the edge of the subject is strongly illuminated. The results of the MIT-Cornell study will be presented at the International Symposium on Computational Aesthetics in Graphics, Visualization, and Imaging, which will run from August 8-10, 2014, in Vancouver, Canada. This conference is collocated with the ACM-sponsored SIGGRAPH 2014.

The research team chose rim lighting for their experiments because it's a difficult lighting effect. Says Manohar Srikanth, a former MIT post-doc who is now at Nokia Advanced Technologies, Sunnyvale, California,

"It's very sensitive to the position of the light... If you move the light, say, by a foot, your appearance changes dramatically."[2]

Even with today's energy efficient LED lighting technology, it would be difficult to do this with a drone battery pack, so the experimental drone was tethered. In operation, the photographer inputs the direction from which the light should come and the width of the light rim.[2] A computer algorithm analyzes the image in the photographer's camera and it commands the drone to position itself to maintain the proper rim lighting effect.[1] Says Srikanth,

"If somebody is facing you, the rim you would see is on the edge of the shoulder, but if the subject turns sideways, so that he's looking 90 degrees away from you, then he's exposing his chest to the light, which means that you'll see a much thicker rim light... So in order to compensate for the change in the body, the light has to change its position quite dramatically."[2]

The "gaffer" drone is a robot helicopter equipped with a continuous light source, a photographic flash, and a laser rangefinder.

(MIT image from study authors.)

The drone computes its required position twenty times each second. The researchers tried a complex algorithm which analyzed the silhouette of the subject, but that proved to be too slow. Instead, it looks at most dramatic change in light intensity in the image, and it measures its width. The drone uses LIDAR for rangefinding.[2]

Although the experiments were facilitated by their being done in a laboratory equipped with cameras that allowed a determination of the drone position for use in the algorithm, there's no reason why accurate enough position sensors couldn't be incorporated into the drone, itself.[2]

The drone positioning algorithm for the rim lighting experiment used simple geometry.

(MIT image from study authors.)

These experiments were done indoors, but there's been a lot of interesting drone photography done outdoors. Realtors have used drones to obtain aerial footage of their listed properties, which is a public example of how useful drones can be. The US Federal Aviation Administration (FAA), in a controversial ruling, has told realtors that they must stop this practice.[4]

The most public example of a possible commercial use of drones is Amazon's proposed drone package delivery service, but that's also been prohibited by the FAA.[5] Amazon has asked the FAA for an exemption for its Prime Air package delivery service.[6]

Presently, the FAA has expressly forbidden, among others, the following commercial uses of drones:[5]

• Determining whether crops need to be watered.
• Photographing an event.
• Photographing a property as a sales aid.
• Demonstrating drone aerobatics at a paid exhibition.

Gaffer Drone

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