Projection Painting Prototype

Combining traditional painting and projection mapping using processing and arduino for the ultimate interactive art experience.

Executive Summary

The structure of the canvas, mixing colors right on the canvas, layer after layer and letting the coincidence help is what makes traditional painting so powerful. However, as a nerdophile person I often miss the undo button and the color wheel of the digital world.

Luckily, I came across the processing movement turning code into art and vice versa. The perfect base to combine vivid richness of painted structure with the interactive and dynamic power of code. In fact, I had the idea of creating a painting hanging in a local club and each time someone enters or leaves  the room the color palette of the painting changes.

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The Twetterhaeuschen is a monitoring tool fueled by an arduino, raspberry pi, node.js and showing the sentiment for a brand or topic on twitter.

The Twetterhäuschen is the world’s first Wetterhäuschen for visualizing the sentiment of a specific topic on twitter. It was built on a raspberry pi, a servo controlled by an arduino uno, using node.js in combination with You can find the code on github to build your own:


  1. The Twetterhäuschen has its web form (index.html) to fill a brand or topic of interest
  2. The keyword is passed on to the server (app.js) which takes care of the API calls using the oauth module. The search is completed with some words to derive a basic level of sentiment, e.g. “love” or “hate”
  3. Taking the reach (number of followers) into account, the ratio between good and bad is calculated
  4. The arduino sets the servo between the angle of 60 and 130 in order to move the two characters Sepp and Susi out of the Twetterhäuschen.
  5. Whereas Sepp represents the dark force, Susi acts as a substitute for ecstacy and elation.

Here is an explanation in German:

php serial connection to arduino uno

control your arduino with your browser… the basic steps.

add the user running the webservice (e.g. www-data ) to the dialout group. (

 sudo useradd www-data dialout

restart your machine

the code for the arduino to turn the LED on and off:

int  pin = 13;
int incomingbyte;

void setup()
pinMode(pin, OUTPUT); // connected LED at Pin13
Serial.begin(115200);      // start communication at 115200bps

void loop()
if( Serial.available() > 0)     // if connection is set
  {incomingbyte =;
  if(incomingbyte == '0')
  digitalWrite(pin, LOW);  // turns LED off
  if( incomingbyte == '1' )
  digitalWrite(pin, HIGH); // turns LED on

and the php file

// $serial->sendMessage('1');
if ($_GET['action'] == "0") {
else if ($_GET['action'] == "1") {