The document provides an overview of optical multi-touch technology, highlighting its function as an advanced human-computer interaction method that recognizes multiple touch points. It describes hardware and software components required for multi-touch devices, along with its applications in various fields like personal computing and advertising. Furthermore, it discusses the implementation techniques and advantages of optical systems over traditional methods, along with references for further exploration.

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DarshanVithani
ME CSE Department,
Parul Institute Of Engineering and Technology
4 October 2013
Optical Multi-touch Technology

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Multi-touch Table

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Contents
Introduction to Multi–Touch Technology
Description of MT Devices
Various Sub System
H/W & S/W Required
Usage of Multi-Touch devices

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Introduction
Multi-touch technology is
an advanced human-
computer interaction
technique that recogonises
multiple touch points and
also includes the hardware
devices for implement it

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Description
The multi-touch device is a user interface
device that will allow a user to interact
with a computer through use of a multi-
touch display.
it is a substitute to the keyboard and
mouse
In this user can directly interact with the
system with their fingers and not only
this but with multiple touches at the
same instant.

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How Does a Touchscreen Work?
A basic touch-screen has
three main components:
Touch sensor;
Controller;
Software driver.
The touch-screen is an
input device, so it needs to
be combined with a display
and a PC or other device to
make a complete touch
input system.

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Touchscreen Technology
Resistive Capacitive Optical

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TERMINOLOGY
 Diffuser: Screen surface for projection.
 IR Lasers: Laser emitting IR Beam.
 IR Led: Led emitting IR.
 Blob - A bright luminescent object
 Blob tracking - Assigning each blob an ID (identifier).
 TUIO - A protocol used for communicating the position, size, and
relative velocity of blobs. (Tangible User Interface Object)
 CCV: An open source software for blob tracking. (Community Core
Vision)
 MT: Multitouch

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 FTIR :Frustrated Total Internal Reflection
 DI: Diffused Illumination
 DSI: Diffused Surface Illumination
 LED LP: Led Laser Plane
 LLP: Laser Light Plane
TECHNIQUES

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FTIR :Frustrated Total Internal Reflection

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Diffused Illumination

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Diffused Surface Illumination

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LED LP

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IR LASER PLANE

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BLOCK DIAGRAM OF TABLE

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BLOCK DIAGRAM OF WALL

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Implementation on Wall

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Camera Sensor & IR Bandpass Filter

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Input Subsystem: The Camera
 We can use a simple
web camera that can
be easily available in
the market.
 It can be made
capable of detecting
IR by simply removing
the filter from the
lens

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Output Subsystem: Projector
 We can use a simple web camera that can be
easily available in the market.
 It can be made capable of detecting IR by simply
removing the filter from the lens

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Computer Subsystem
 A personal computer with 20 GB
free hard disk space, 1GB RAM and
PIV + processor can be efficient
enough.
 The Windows XP/7/8 operating
system was chosen because the CCV
package is highly supported in
Windows.
 It is also support Mac OS ,linux
Debian , Ubuntu & Fedora etc

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Application Development
 Adobe Flash / Flex / Air
 Browser & Web (HTML/CSS/Javascript)
 C/C++ (CCV/OpenCV/OpenGL/OpenFrameworks)
 Java (Android/Processing.org)
 C# (.NET/Silverlight/WPF)
 Objective-C (Cocoa/iPhone)

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APPLICATIONS
 Personal Computing
 Advertising
 Graphics
 Audio Mixing
 Video Playing
 Computer Gaming
 Slide Presentations
……and many more!

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CONCLUSION
 Multi-touch technologies have a long history. Mostly multi Touch devices
have limited resolution, are relatively complex, and don't easily and
inexpensively scale up to large dimensions.
 Optical Multi-touch technology use FTIR technique that is simple and easy
to implement . It provides any resolution displays supported with high
graphics.
 In this research , it requires a significant amount of space behind the
interaction surface. Instead of this we can use Raspberry Pi & its
introduction covered by Pranav Pathak.

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REFERENCES
[1] Low-Cost Multi-Touch Sensing through FTIR by Jefferson Y. Han
[2] Buxton, W., Hill, R., and Rowley, P. 1985. Issues and Techniques in
[3] Touch-Sensitive Tablet Input
[4] Donald Hearn ,M Pauline Baker, Computer Graphics C version, 2/E
[5] Pearson Education ,2003
[6] Buxton, Bill. 2008. Multi-Touch Systems that I Have Known and Loved.
[7] URL: http://www.billbuxton.com/multitouchOverview.html
[8] How to build a multi touch by Harry Vaan Der
[9] Opensource,MultitouchDisplay,http://www.technologyreview.com/Infotec
[10] OpenCV on the Raspberry Pi
, http://www.raspberrypi.org/phpBB3/viewtopic.php?f=37&t=6354

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Thank You
Darshan Vithani, 4 October 2013