Posts Tagged ‘Tracking’

There are three different types of LEDs discussed here:

  • sfh 485p (angle of 80 degree, 200mW)
  • sfh 487 (angle of  40 degree, 200mW)
  • sfh 4550 (angle of 6 degree, 180mW)

The total power dissipation is noted after each led type, because this is actually the power that the led consumes and somehow transforms to light energy.

Here are the images for sfh 485p:


Here are the images for sfh 487:


Here are the images for sfh 4550:


Obviously the sfh 4550 works the best out of them. The hand can be seen much better. Even the sfh 487 (with only 40 degree) creates a better image of the hand. I don’t know whether it’s actually the lower angle or something special about the sfh 4550, but the observation indicates that the lower the angle the better the hand can be seen. Upon this obervation i tried the same test with the diffusor material 7D0006 and here are the results.


This experiment shows that the sfh 4550 seems to fit better for DSI. They create visible beams within the EndLighten, but this could be removed by a background subtraction algorithm.

Tim Roth explained a technique that is currently known as DSI (Diffused Surface Illumination) and promises for finger tracking and fiducial tracking at the same time. This approach offers benefits of the rear DI (Rear Diffused Illumination) technique and establishes even illumination distributed over the surface by means of a special acrylic (EndLighten).

  • DI
  • DSI

After doing ample investigations and having read reports on experiences from nuigroup… i thought.. alright.. this is worth a try.. and here we go… hum… now lets try it hehe

The project aims to switch the illumination technique of our small DI table (known as Xenakis – music creating tangible interface [1]) from rear DI to DSI. Here are some pictures of the table:

  • Table
    Xenakis Table
  • Small blueprint of the table
    Xenakis Construction
  • What’s inside
  • Music creating tangibles
    Xenakis Tangibles


[1] M. Bischof, B. Conradi, P. Lachenmaier, K. Linde, M. Meier, P. Pötzl, and E. André, XENAKIS – Combining tangible interaction with probability-based musical composition, In Proceedings of the Second International Conference on Tangible and Embedded Interaction (TEI’08), ACM, Bonn, Germany, Feb 18-20 2008, pp. 121-124

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