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Multitouch – How To

How To Make a Multitouch Surface

There are several ways to make a multitouch surface. There are capacitive, resistive, acoustic, and other non-traditional techniques. Our focus will be on optical techniques since they are the easiest and most cost effective for the average person to create. The most popular optical techniques are:

  • Frustrated Total Internal Reflection (ie. Perceptive Pixels)
  • Rear Diffused Illumination (ie. Microsoft Surface)
  • Front Diffused Illumination (ie. MTmini, MTbiggie)
  • Diffused Surface Illumination
  • Laser Light Plane
  • LED Light Plane

Optical Multitouch Techniques

Each technique utilizes 3 main components:

  1. Infrared Camera (or other optical sensor)
  2. Infrared light
  3. Visual Feedback (projector or LCD)

setup An infrared camera is pointed at the touch surface and detects when fingers/objects touch the surface. Infrared light is used to distinguish between a visual image on the touch surface and the objects/fingers being tracked. Since most systems have a visual feedback system where an image from a projector or LCD is projected or placed below the touch surface (the MTmini does not), it is important that the camera does not see this image when tracking objects/fingers on the display. In order to separate the objects being tracked from the visual display, a camera can be modified to only see the infrared spectrum of light (by removing the infrared filter and replacing it with a visible light or bandpass filter); this cuts out the visual image from being seen by the camera and allows the camera to only see infrared light that illuminates the objects/fingers on the touch surface. The projector is connected to a computer in order to display the software on the touch surface. The camera is connected to a computer and a tracking application uses the camera image to track and create touch coordinates.

6 Optical Multitouch Techniques

Click the image or title to view a description, diagrams, images, and other resources about a particular technique.

Software

Resources

This page is still being developed. Stop by often to see updates and more information for building your own multitouch surface.

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  • Can you build perceptive pixel like Jeff Han did?

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  • Fiorenzano

    obrigado.
    não sou um expert no ramo de informatica por isso gostaria se possivel que usassem uma linguagem menos tecnica pois tem alguns itens que não sei nem o que significa, só quero saber o que devo comprar´para construir uma tela touch para usar o virtual dj e na mais que isso.
    agradeço e muito se puderem me ajudar.

  • Iaoaioaia

    seth i need a tutorial how to make infrared webcam 🙁

  • denins

    hi im a noob in this i downloaded all the software, after calibration how do i make ccv control the mouse option i have windows 7

  • Pingback: How to make a Low cost Multi- Touch Pad « Learning Hotspot()

  • Hi
    I was just wondering if I can do the llp method and instead of using a projector can I use a lcd screen and if it is possible can you please show me how and YES I have gone to http://nuigroup.com/forums and I can’t find it. So thank you in advance
    Steven

    • You can, but you’d need to take apart the LCD. On nuigroup search for ‘LCD’. There’s many different posts about people using LCDs and in conjunction with LLP. I believe there’s posts with pictures where people have taken apart their LCDs.

    • Thank you very much…..BTW What method would you recommend that will give the best blobs so that the project can give the most accurate touch point

  • sir, i need help with camera plz tell me which one i should buy.

  • ishwar

    can normal logitech pc webcam is used to implement FDI pls reply i m eagerly waiting to do it but i m unsuccessful with my MTsetup

  • Ralph Tyndall

    Does the MTBIggie need extra infrared lighting from the sides??

    • No, not if it’s using ambient IR light in the room.

  • ash

    hii , is any game can work even its not a touch game ?? please i need the answer quick 🙂 , and thank you for you great work …

  • kiran

    hi , ccv doesnot work please help me

  • Monika Khurana

    hi, i want to know what are the basic algorithms used in blob extraction and detection for my research , kindly provide me with relevant sources for reading that.

  • fred

    Hi again, i can control the mouse with the WIndows Mouse Driver but i cant click with one Finger? Whats the matter about that? Do i have to change some settings for One-Hand use?

    • To click, I believe you use a second finger (1 finger to move, other finger to click).

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