Multi Touch 1

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Name: Rajesh Samanth

RegNo: 100919065

1Multi-Touch


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Contents Introduction Components

Multi-touch

Why Multi-touch

Multi-touch Techniques

Display Techniques

Applications

Future directions

Conclusion

References Multi-Touch 2


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Introduction

User can interact with what is displayed

directly on the screen

Detect the presence and location of a touch

within the display area

One point of contact at a time

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Components

Touch sensor

Controller

Software driver

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Touchsensor

Is a clear glass panel with a touch responsivesurface

The responsive area of the panel covers the

viewable area screen

Has an electrical current or signal

Touching the screen causes a voltage or

signal change

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Controller

It is a small PC card

Used for connecting and translation

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Software

It allows the touch screen and computer

to work together

It tells the operating system how to

interpret the touch event information

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Allow users to compute without

conventional input devices

The amount of simultaneous users is more

This multi-touch effect is achieved through

a variety of means

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Why Multi-Touch

Seeing hands not points

Cross platform

Multiuser displays

Variable conditions

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Multi-Touch Techniques

Diffused Illumination (DI)

Front Diffused Illumination

Rear Diffused Illumination

Laser Light Plane (LLP)

Diffused Surface Illumination (DSI)

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Front Diffused Illumination

Visible light is shined at the screen from

above the touch surface

A diffuser is placed on top or on bottom of

the touch surface

When an object touches the surface, a

shadow is created in the position of the

object

The camera senses this shadow

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No need for a compliant

surface

Can use any transparent

material like glass

An enclosed box is not

required

Can track fingers andhovering

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Cannot track objects

Difficult to get even illumination

Greater chance of

false blobs

Not as reliable(relies heavily on

ambient lighting environment)

DemeritsMerits


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It works on the same technique of front diffused illumination

When an object touches the surface it reflects more light than thediffuser or objects in the background;

Figure 3: Rear DI schematic

Rear Diffused Illumination


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No need for a compliant surface,

just an diffuser/projection surface

on top/bottom

Can use any transparent materiallike glass

No soldering (you can buy the

IR-Illuminators ready to go)

Can track objects, fingers,

hovering

Difficult to get even

illumination

Blobs have lower

contrast (harder to pick

up by software)

Greater chance of

false blobs

Merits Demerits


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Laser Light Plane (LLP)

Infrared light from a laser(s) is shined just above thesurface

The laser plane of light is about 1mm thick and is

positioned right above the surface.

when the finger just touches it, it will hit the tip of the

finger which will register as a IR blob

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No compliant surface

An enclosed box is not

required

Simplest setup

Could be slightly cheaper

than other techniques

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Cannot track traditional

objects

Not truly pressure

sensitive

Can cause occlusion ifonly using 1 or 2 lasers

Multi-Touch

Merits Demerits


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DSI uses a special acrylic to distribute the IR evenly across the

surface.

This acrylic uses small particles that are inside the material,

acting like thousands of small mirrors.

When you shine IR light into the edges of this material, the

light gets redirected and spread to the surface of the acrylic.

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http://wiki.nuigroup.com/Image:Dsi2.jpg


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Merits

Unlimited number of

touch points

No compliant surface(silicone)

Is pressure sensitive

Demerits

Sensitive to ambient light

Endlighten Acrylic costs

more than regular acrylic

Blobs have lower contrast

(harder to pick up by

software)

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Display Technique Projector:

used to display visual feedback on the table.

There are two main display types of projectors:

DLP

LCD

LCD (Liquid Crystal Displays) uses the same

technology that is in your flat panel monitor or laptop

screen

DLP (Digital Light Processing) is a technology that

works by the use of thousands of tiny mirrors moving

back and forth.

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Technology-enhanced Multi-touch

Tabletop Home Controlling

System

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Three main components:

- Camera-based multi-touch tabletop

- Software application namely home appliances controlling module

- Linux MCE home server


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Multi-touch Tabletop Home Controlling System


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APPLICATIONS

Use of multi-touch screens replaces traditional inputs like

mouse, joystick and Keyboard.

Used in electronic-music instruments.

A multi-touch sensor designed for robotics to enable

sensing of shape, orientation, etc.

Multi touch input picture drawing.

Sensor frames for ex. sensing the identity.

Multi touch screens are used as digital desks.

For smart phones ex. Simon, i Phone, etc.

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Future directions

Security services

Locate landmarks, uplink info to cellular phone

Gaming

Governmental use

Concept mapping

Music composition, recording and mixing.

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Conclusion

- Multi touch is definitely an area which will

expand in future.

- Since the technology is here, we cant say whywe should remain at the traditional single input

interfaces for long.

- In the years to come multi-touch systems are

expected to show strong growth due toimproved designs,reduced component prices and

better software development.

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ReferencesPaper:

[1] Gary L.Barrett"Putting the 'touch' in multi-touch: An

indepth look at the future of interactivity." whitepaper by

Touch International,2009

Web References:

http://nuicode.com/attachments/download/115/Multi-

Touch_Technologies_v1.01.pdf

http://www.billbuxton.com/multitouchOverview.html

http://www.touchinternational.com

http://foe.mmu.edu.my/digitalhome/project.html

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http://nuicode.com/attachments/download/115/Multi-Touch_Technologies_v1.01.pdfhttp://nuicode.com/attachments/download/115/Multi-Touch_Technologies_v1.01.pdfhttp://nuicode.com/attachments/download/115/Multi-Touch_Technologies_v1.01.pdfhttp://www.touchinternational.com/http://www.touchinternational.com/http://nuicode.com/attachments/download/115/Multi-Touch_Technologies_v1.01.pdfhttp://nuicode.com/attachments/download/115/Multi-Touch_Technologies_v1.01.pdfhttp://nuicode.com/attachments/download/115/Multi-Touch_Technologies_v1.01.pdfhttp://nuicode.com/attachments/download/115/Multi-Touch_Technologies_v1.01.pdf


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