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Front Diffused Illumination Multitouch Technique

In Front DI, infrared light is shined at the screen from above the touch surface. A diffuser is placed on top (preferred) or on bottom of the touch surface.  When a finger or object touches the surface, a shadow is created under the object and seen by an infrared camera below the surface. This method is what the MTmini uses, but without the need for infrared light (since there is no visual display to remove). The MTbiggie also uses this technique. An image is displayed by using a projector connected to a computer pointed towards the projection material.


Parts List

  • Clear, Sturdy Surface (Glass, Acrylic, Polycarbonate, Plexiglas, etc.)
  • Infrared Lighting (The Sun, Infrared LEDs, Infrared Illuminator, Ambient Light/Lamps, etc.)
  • Diffuser/Projection Surface (Vellum, Mylar, Lee Filter, other, etc.)  – For displaying an image and scattering light. *Note: The Diffuser/Projection Surface must let some light through.
  • Infrared Camera/Modified Webcam

Camera Image Examples



Video Examples



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  • zabdi

    hola no se mucho de esto pero quiero saber cuales son los software que se necesitan y cual es el codigo que se ocupa por favor es k lo necesito para una tarea

  • Marc

    hey seth, is it possible to get the first camera image example?
    I would use it for my degree dissertation…

    thanks in advance

    • Sure, you can use that image Marc. That’s biggest file I have. So, just right click and save as to download it.

  • Sid

    hey i m trying to use in it in my school as its the scince fic day it helds in night there will be no sun light so what should i use? can i make a infra red lighting stand or something?please tell me! if you are on skype please give me your id i want to call you and ask my all difficulties! please!!!

  • Sid

    hey can i use multiple cameras to make it better?

    • Yes there’s a multicamera version of the software.

  • Sid

    will it boost up the speed and better the touch if i put multiple cameras?

    • No, it won’t increase the speed. It’ll increase the accuracy.

  • Sid

    thanks thanks my science fair was fabulous my multitouch screen was appreciated by all!!
    and i am waiting for the results i will upload some pics of my multitouch screen! thanks thanks 

  • Juanpelotas

    what software do you use to catch the movement of the finger?

  • Jack

    Hi seth, would higher front ir illumination improve the contrast of the quiet surface and the shadow of the finger, allowing for better accuracy/less false blobs? thanks a lot

    • It may help. It’s hard to sell. The best lighting is even lighting all around.

  • Sarah González

    Hi there.

    I’m Sarah González, currently i’m studyng at the UDC in School of Visual Design in Manizales-Caldas-Colombia, currently investigate on touch technology and the application of that in the interaction design applied in interactive instalations.
    I would like to ask u ¿What kind of software u used to develop MTBiggy Project, and if it is possible develop applications such as designed-interfaces, for this type of “craft-pad” technology.
    Thank u very much for your FeedbacK!

    Sarah M González.

  • Atharvasg

    Hey…..Which Tracking Software is used here???

  • Jay Curtis

    Hey Seth,

    I’m getting into MT surfaces and discovering your site has been invaluable, many thanks!

    I’m building the MT Biggie and have had success so far in using CCV, tracking blobs and sending them via Osculator to ableton live. However the lighting required to achieve good results has made the projection surface far too illuminated to actually see the projection! I’m stuck as to how to achieve a balance of both solid backlighting and a dark enough projection surface to effectively throw onto.

    I’m using my glass desk with an A1 size sheet of 80gsm white paper as a diffuser, any help appreciated!

    • Jay Curtis

      Here is a shot of the amount of incandescent light needed with the current setup to track blobs effectively. Perhaps you could suggest another source of IR that would be more effective?

    • When using a projection, you’ll need to use IR light (not visible light) along with a IR camera. You can learn more at http://NUIGroup.com/forums

    • Jay Curtis

      Thanks for your speedy reply! My webcam mod is working well as an IR camera, I’ll take a look at the forums for a cheap IR light solution – unless you can you suggest a cheap IR light?

    • Any type of IR lamp should work. I’m not completely sure where you’d you get one, but might be able to just search online.