Robot Darkroom

Guests take a picture at a photo booth outside a glass room. Inside, an arm carries a 1 m strip of ultraviolet LEDs; swept 2 mm from a sheet of photochromic paper, the strip prints the picture in violet, and it fades back to white within 10–20 s. Between prints the arm dances with the strip lit, and it notices the people outside the glass.

The room

It ran through the evening of Todos Bien @ Volvox on 10.02, on its own. The ceiling light follows the show, dimming for each scan.

Drawing with light

The pigment fades faster than one pass can write a picture, so a scan is eight passes, down and up, slowing from 0.3 to 0.15 m/s with the LEDs lit both ways: about 51 s. TouchDesigner writes the image column by column as the strip moves.

Behaviours

Between prints the arm plays from a library of 70 short clips at four positions: it peeks, nods, bounces, shies away, wipes the air. None of them is keyframed: they are generated as a library, and the show strings them along an energy arc, never the same one twice in a row.

Noticing people

A depth camera watches the space in front of the glass. Step onto the spot or wave, and the arm leaves what it was doing, turns to you, follows you along the glass, and nods goodbye when you go. On the real arm it has engaged 9 times over four runs with no unsafe pose.