Last year we have built an interactive Christmas tree for the entrance hall of Czech Technical University in Prague at Karlovo namesti, this year we were asked by journalists from a technological on-line magazine Technet to put our tree on board of the service tram, so that even wider audience would enjoy it. This tram lubricates the rails all around Prague to minimize noise and is equipped with a camera streaming live video on the Internet. The installation was done in cooperation with Prague Public Transit Co. and Czech Slow TV. You can see the video stream and control the tree here
The Christmas tree is decorated by a string of individually addressable RGB LEDs (WS2811) controlled by Raspberry PI 2. Blinking of the lights is far from random, it is governed by a numerical model of wave equation simulating propagation of waves along the string. Everybody can influence this virtual environment by their own wave sent over a web interface. These waves interfere and create momentary colorful images born in interaction of all connected users.
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