3. Contents
Introduction to Surface Computing
Description of MT Display Devices
Various Sub Systems
H/W & S/W Required
Usage areas of MT Devices
Practical approach to multi-touch devices.
4. Introduction
Surface computing is the term for the
use of a specialized computer GUI in
which traditional GUI elements are
replaced by intuitive, everyday objects.
Instead of a keyboard and mouse, the
user interacts directly with a touch-
sensitive screen.
5. 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. Thus, 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.
6. How Does a Touchscreen Work?
A basic touch-screen has three main
components:
1. Touch sensor;
2. Controller;
3. 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.
8. Resistive touchscreen
Structure
Resistive touch screens
consist of a glass or
acrylic panel that is
coated with electrically
conductive and resistive
layers made with indium
tin oxide (ITO) .The thin
layers are separated by
invisible spacers.
9. Projected-capacitive touchscreen
During a touch, capacitance forms between the
finger and the sensor grid.The embedded serial
controller in the touchscreen calculates touch
location coordinates and transmits them to the
computer for processing.
11. 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
12. TECHNIQUES
FTIR :Frustrated Total Internal
Reflection
DI: Diffused Illumination
DSI: Diffused Surface Illumination
LED LP: Led Laser Plane
LLP: Laser Light Plane
13. PRINCIPLE OF WORKING
Mesh of IR is generated on screen.
Frustration is created on the surface if
touched.
Detected by the camera.
Blobs are created and sent to tracker.
Tracker communicates with
application.
18. Building LLP Set Up
Table with glass top.
Camera (PS3 eye/ MS Lifecam)
Projector
Mirror
Four 780 nm IR lasers
Four Line generators 89 degree each
Rosco grey/Tracing paper
USB cable for powering lasers
Under exposed – undeveloped negative roll
Cello tape/knife/wire/insulating tape..etc.
23. Input Subsystem: The Camera
We are using a
simple web camera
easily available in
the market.
It can be made
capable of detecting
IR by simply
removing the filter
from the lens
24. The Projector
A rear projection setup allows the projector to
be placed inside the multimedia table.
However, with the size of the multimedia table
in mind, there is a strict requirement on the
“throw” distance of the projector.
An extremely short throw distance projector
was found to overcome the problem.
25. Output Subsystem
A diffusion layer is
needed to provide a
surface for the
projected image to
be displayed.
To diffuse the
projected image
through rear
projection a sheet of
tracing paper will
be used.
27. Computer Subsystem
A personal computer with 20 GB free hard disk
space, 1GB RAM and PIV + processor can be
efficient enough.
The Windows Vista operating system was chosen
because the CCV package is highly supported in
Windows.
28. Programming for the MT
CCV is an open source C++ software package
that contains code to analyze data from a
camera, detect IR blobs from within the
data, interpret that IR blob data, and generate
TUIO events for the application to interpret.
Since most operating systems only expect one
mouse click at any single time, a new event and
protocol must be used to interpret any number of
touches, the TUIO protocol.
29. CCV: Hardware–Software Interface
CCV acts as a driver for the multi-touch table device
so that the computer embedded inside can interpret
touches from the user or users.
Individual applications can be written to interpret
the data supplied from CCV and provide feedback
to the display for the user or users.
30. CCV Calibration
The CCV library comes
with an interface to
calibrate and test the
blob detection for a
multi-touch setup.
Also, CCV comes with
software to calibrate
and test the camera that
will be used with the
multi-touch table.
31. Application Development
Many different platforms can be used to
develop multi-touch applications utilizing
TUIO events. Such platforms include:
Adobe Flash
Java
C++
Python
Our demo application has been developed
with ADOBE FLASH and is an open source
s/w.
32. BUILDING MINI MT
Cardboard box
Cellophane sheet
Camera
Knife/cello-tape/A-4
sheets
33. APPLICATIONS OF MT
Personal Computing
Graphics
Audio Mixing
Video Playing
Computer Gaming
Slide Presentations
……and many more!
36. That’s All….
Thank you…
For any assistance in building your own setup
or for any other help feel free to contact:
www.facebook.com/princejerry06
www.facebook.com/technicabar
www.twitter.com/princejerry06
www.twitter.com/technicabar
rishabha.garg06@gmail.com