Painting A Wall With Light Using Water As Ink

This art installation uses a fantastic concept. The wall can be painted using water as ink which lights up a huge grid of white LEDs. This offers a very wide range of interactive possibilities since water can be applied in so many ways. Grab a paint brush, wet your finger, use a squirt gun, or mist with a spray bottle and the lights will tell you where you hit the wall.

We’re hoping a reader who speaks both French and English might help out by posting a translation as a comment on the prototyping video. In it, [Antonin Fourneau] shows off the various prototypes that led to the final product and we’d love to know what he’s saying. But by seeing the prototypes, then watching the English promo video after the break we can make a pretty good guess.  The boards have a hole that fits the flat-lens LEDs perfectly. This creates a mostly water tight seal to keep the liquid on one side while the leads are safe on the other. The water side has squiggly pads which allow droplets of water to complete an electrical connection.

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Computer-aided Paint Brush

[Nirav] painted this masterpiece by hand… with a little help from a computer. He calls it the semi-automatic paintbrush because you do need to move it over the canvas by hand, but a computer decides when to dispense the ink.

He’s using a piece of hardware we looked at back in September called the InkShield that got a boost from Kickstarter. It’s an Arduino shield that drives an inkjet printer cartridge. The trick is how to know when the cartridge is in position for printing.

The system uses visual processing for that. [Nirav] added an IR led to the cartridge, and uses a camera to extrapolate its position. He actually reused a Python homography module which he had written for use with a projector. That setup was developed as a digital white board, but works just as well for this purpose.

He mentions that results like this won’t be featured in an art museum. But the look is unique, and we’d love to make a set of geeky thank-you notes using the technique.