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Contents © 2017 Golan Levin and Collaborators

Golan Levin and Collaborators

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Ghost Pole Propagator II

2016 | Golan Levin

Ghost Pole Propagator II

Ghost Pole Propagator II revisits a 2007 interactive installation originally developed for video projection in the cellars of a 13th century castle. In this version, commissioned in December 2016 by the Houston Day for Night festival, the project has been reimagined at a significantly larger scale, and rendered with the perceptually remarkable light of laser beams.

Overview video, 1’54" [VimeoYouTube]

Stick figures are an extremely compact yet exceptionally expressive means of representing the human form. The graphic simplicity of such figures belies their emotional force. By eliminating unnecessary details and reducing visual elements to their absolute essence, stick figures accomplish a powerful, immediately apprehensible and possibly universal communication of human presence, attitude and gesture. Looking around, we find inspirational stick figures in ancient petroglyphs; in children’s drawings; and in the pioneering motion studies of the 19th century French chronophotographer, Étienne-Jules Marey.

An image processing technique called skeletonization (or the medial axis transform) can be used to generate stick figures from the silhouette of any shape. This algorithm is commonly employed in recognizing letters and numbers by some OCR (Optical Character Recognition) systems. However, it produces particularly engrossing abstractions when applied to the silhouettes of people. In the Ghost Pole Propagator installations, these stick figures are computed, in real-time, from the moving silhouettes of participants, visitors, and passers-by.

The animated "skeletons" produced by this technique preserve all of the gestural qualities of a visitor’s movements and gait, while simultaneously abstracting their appearance into a proto-symbolic, timeless, and poignant petroglyphic character. The result is a universal communication of presence, attitude and gesture.

In the Ghost Pole Propagator II installation, these vector-based characters are drawn at gargantuan scale using a computer-controlled laser, which allows for a significantly larger display than a conventional video projector. Producing an impossibly crisp and chromatically pure line, the unique visual quality of the laser display is ideally suited to rendering the sketchlike skeletons produced by the installation.

Participants see their own stick-figures, mirroring their movements. At the same time, they also observe the animated stick-figures of previous participants, whose movements had been recorded moments or hours earlier. The result is a surface populated by the animated traces of the site’s inhabitants and guests.

By capturing and replaying the figures of the passersby in its environment, the installation produces a layered and dynamic tapestry that reflects the history and activity of its locale. The format of the work is variable; in other configurations, the project operates as a kind of "interpretive monitoring station" or "poetic surveillance system" for nearby pedestrian traffic.


Credits and Acknowledgements

Ghost Pole Propagator II was developed in openFrameworks, a free, open-source C++ programming toolkit for the arts, with technical contributions and on-site assistance from Dan Moore. The project uses Seb Lee-Delisle's ofxLaser openFrameworks addon, as well as Memo Akten's ofxEtherdream and ofxIlda addons, originally based on work by Daito Manabe and Yusuke Tomoto, for laser control with the Etherdream DAC. The project obtains very significant speedups through the use of the ofxLaserTSP addon, developed by Bryce Summers, for laser-specific path optimization with a directed Traveling Salesman Problem solver. Thanks to these artist-developers and the rest of the openFrameworks community for sharing the love.

Ghost Pole Propagator II was commissioned by the 2016 Day for Night festival, Houston, under the curatorial direction of Alex Czetwertynski. Additional support for this project came from the Frank-Ratchye STUDIO for Creative Inquiry at Carnegie Mellon University. Laser projection and management was provided by ILDA-certified laserist, Tim Walsh of Laser Spectacles, Inc. The project was documented by Claire Hentschker, Tom Hughes, and Houston Public Media.


Media

An archive of high-resolution images of Ghost Pole Propagator II can be found in this Flickr album.