Interactive Window Installation, progressing beyond the Max/MSP solution

After our post a few weeks ago about a new interactive window installation, we had some interesting and helpful suggestions, but one email in particular stood out.

Paul Anderson wrote to us briefly with an offer to help and after a quick introduction of his incredible depth of knowledge of all things electronic shortly thereafter, he showed up yesterday with the sensor pictured above. Basically, it’s used for industrial automation and I can’t recall the name of it, but see that red light, that’s the important part.

Pictured above, Paul is holding up this device to the window on the inside of CIVIC SPACE and our artist-in-residence, Sam Lefort, places her hand on the window from outside, and that little light turns from green to red. I can’t recall exactly what it’s detecting (I’m hoping Paul can fill in some blanks in the comments), but essentially by dialing in the right sensitivity, you can get this thing to act as a trigger when someone’s hand is in front of it through the window. This gets us past trying to use computer vision in Max to detect the presence of a hand, which would have run into some challenges dealing with the range of lighting conditions we deal with at the window (pictured below).

Still assuming that ¬†we’ll use Max to record the audio (as Stephen had suggested in the comments) and add some other useful automation like date/time, possibly some early EQ or amplification, and maybe even setting this thing up so it will tweet us when it’s recording and automatically upload it to our servers, or maybe something else entirely.

Anyways, I’m confident in saying that I’ve never been so excited to see a little red light turn on.

One Reply to “Interactive Window Installation, progressing beyond the Max/MSP solution”

  1. It detects a change in capacitance. Basically, when you have two conductive things(like a hand and a metal plate) separated by an insulator(like glass), it can store charge. This is similar to the way a balloon stores static electricity. The capacitive touch sensor uses an oscillator, a capacitor and inductor ringing like a bell. If you change the shape of the bell, you change it’s frequency. The same applies to the oscillator used in the sensor. The presence of the hand adds capacitance, making the frequency the oscillator is ringing at change. It detects that change and uses it to turn on a switch.

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