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  • There's more to read
  • TypeStudy
  • CourseInteractive Media
  • Semester3rd
  • SupervisorDaniel Rothaug
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Pendulum is an experimental project using a pendulum as an interaction tool. It contains two examples: One is the visualization of the pendulums motion, counting the angles it is moving along on a circular graphic. The other is an interactive sound generating machine: One can set points with the pendulum on the display surface beneath, which will be sounded by the movement of the pendulum, creating an ever changing beat of random sounds:

Let’s try how the pendulum can be used as a tool for user interaction
My focus for the semester

This was basically my self-assigned task description for my 3rd-semester project in interactive media. I thought the pendulum could be an interesting tool for user input and I wasn't aware of any projects who actually use one. So I decided to give it a try.

The very first prototype for figuring out how a pendulum actually feels like and to get first ideas for interaction concepts and what to use the pendulum for. Some concept sketches on the right.

I didn't spend too much time thinking about every possible idea, what to visualize etc. and jumped early into code instead, to approach the topic from an experimental side. Following there are some examples of basic code experiments – some prototypes already contain ideas which made it to the final result eventually. At this time, there was no hardware built, so I mostly used the cursor for "simulating" a pendulum.


Random ticking circles with lines to the pendulum position

Setting points on a surface with the pendulum by keeping it still for a few moments. This principle was used in the final result for setting sound dots.

Defining a timeframe by using two axis, one for the start, the other for the end time.

Amplifying the pendulums motion using a visual and audible “tick” whenever it crosses the center

Using particles to show the pendulums path over a short time period

Testing the behaviour of the visualizing dots

Tools & Technology

During prototyping, I decided to build a back projection table as a display surface under the pendulum, which at the same time is used for tracking the pendulums position. To accomplish this, I put an infrared led into the pendulum which projects an (for the human eye invisible) dot on the semi-transparent foil. This dot again is tracked by a cheap webcam. I had to open the camera and scrape off the infrared cut-off filter on the lens to make the camera receive infrared light. I then used a small piece of exposed photographic film, which makes a cheap filter that passes infrared light only. This setup creates a black image with a bright white dot, which is rather easy to track with Processing. The projection is done by a common touch-table setting, containing a projector facing down on a mirror to enlarge the projection area.

Processing runs the main software, doing the pendulum tracking, everything visual and sending MIDI notes to Garageband which plays the assigned sounds.


Thank you :)