Project Description
An interactive punching bag installation for the Runaway Circus themed Jerusalem Design Week. Using computer vision, both boxer and punching bag are identified during a workout then in real-time transformed into two identical digital cylinders (punching bags). The computer monitors the twos “dance”, and captures moments of their intersection, outputting “snapshot” 3d files which have then been realized in the physical world as freak punching bags.
Designed with Dov Ganchrow, Sarit Youdelevich, David Oppenheim.
cpu, camera, projector, custom software,
How the system worked
Visitors trained on a black “generating” bag while a camera watched. Computer vision software detected the boxer and the bag by their movement, framed each of them, and at the moment the two overlapped it captured a snapshot of the interaction. That snapshot, two intersecting rectangles, was translated into two intersecting cylinders and calculated as a 3D volume. The volumes were then unfolded into flat sewing patterns, cut from reinforced vinyl and sewn by hand by a veteran leather craftsman into new, conjoined Freak bags, which were hung in the space for the next visitors to strike.
A live projection showed what the computer was seeing in real time, with a running timeline of earlier captures turning into 3D forms, so every workout became a visible part of the design process. We chose computer vision over impact sensors or accelerometers because the installation had to withstand tens of thousands of visitors.
Context
For the 2021 Jerusalem Design Week, themed Runaway Circus, the installation turned an upper-floor gallery at Hansen House into a neon-lit boxing gym with mirrored walls, foam flooring and hanging bags. The title also nods to Tod Browning’s 1932 film Freaks. Beyond its playful mechanics, the work reflects on conflict: in the computer’s eyes the striker and the struck are equals, and once fused into a single sewn object neither can be told apart.
The project is discussed in detail by Dov Ganchrow in “A Punching Bag with Computer Vision Leverages Motion for Creative Output” (Presses universitaires de Bordeaux, 2026). See also Jerusalem Design Week 2021.
