Interactive Multi-Touch Powerpoint prsentation

1. SURFACE COMPUTING
&
MULTI-TOUCH DISPLAY
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. 
Surface Computing
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6. 
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.

7. 
 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.
How Does a Touchscreen Work?

8. Touchscreen
Technologies
 Resistive
 Capacitive
 Surface
 Projected
 Optical imaging
 FTIR
 DI
 DSI

9. Resistive Touchscreen
 Composed of multiple layers separated by thin spaces
 Using indium tin oxide (ITO) layers
 Different standards
 4, 5, and 8 wire types
 Each have advantages

10. Resistive Touchscreen
 User Presses Down
 Contact is Made
 Uniform Voltage on
First Screen for X
 Same on Second screen
for Y
 Happens
instantaneously

11. 4-Wire design
 One screen for X
 Another screen for Y
 Both create voltage
gradient.
 Uses voltage divider

12. Advantages & Disadvantages
 Works well with
fingertip or stylus input
 Generally most
affordable touchscreen
technology
 Rugged/Durable
 Has multi-touch input
capabilities
 Not as accurate
 Multi-touch much more
complex
 Usually no discretion
between stylus and
hand
 More pressure needed

13. Capacitive Touch Technology
 Consists of:
 Insulator (glass or Air)
 Conductive coating
(ITO)
 Two types:
 Surface
 projected

14. Surface Capacitance
 Only one side is coated
 Electrodes at the edges
 Distribute voltage

15.  Capacitor forms
 Current flows
 Determine location
 Controller
 Ratio of currents
,
 XY coordinates
A
R
ρ×
=


1
αi
R
Surface Capacitance

16. Projected Capacitance
 Two parallel ITO(Indium Tin Oxide ) layers
 Two sheets of glass

17. Projected Capacitance
 E Field is projected through
glass
 Finger couples with E field
 Capacitance changes
Capacitor at each point on the surface

18. Surface vs. Projected
 Limited resolution
 Single touch
 Operation with direct
contact
 High resolution
 Multi touch
 Operation with
indirect contact

19. 
Multi-Touch Using Infrared

20. Frustrated Total Internal ReflectionFrustrated Total Internal Reflection
A process by which light is trapped within a medium and
can be interrupted by a third medium of higher reflective
index to cause light to escape.

21. Diffused Illumination

22. 
Diffused Surface Illumination

23. Alternative Single-Unit
Design
Eliminates rear
projection
Expensive
Robustness

24. 
Software
Surface Capture via Detector Digitized View

25. Software Cont.
 Interpret and Relay Information
 Assign Objects or gestures with Unique ID# and
location
 Compare and Execute
Digitized
Object
Application
ProtocolRaw Data Feedback to User

26. 
 Universal Design Principles
 Utility for all users
 Simple and intuitive
 Touchscreens depend on visual feedback in order to
use
Improving Accessibility?

27. 
 Cursor movements as
command shortcuts
 Takes place of
keyboard shortcuts
 Useful in applications
where keyboard use
is less prominent or
undesirable
Pointing Device Gestures
Above: Some possible cursor movement patterns for use
in gesture support.

28. Implementation: Step 1
 Filter Input
 Sampling rate
 Smooth out input data, get rid of unnecessary “noise”
 Simplify data analysis

29. Implementation: Step 2
 Vectorize
 Separate x- and y-component
 Compute dominant component and ignore smaller one
 Store in array

30. Implementation: Step 3
 Matching
 Match captured vector array to pre-defined gesture
library
 If no match, pop smallest vector from array and repeat
matching process

31. Example
Fig. 1 – User input
Fig. 2 –
Captured/filtered
pointer data
Fig. 3 – After
vectorization
Fig. 4 – Final
matching result

32. 
 Allows for a quicker and more efficient UI
 Universal Design
 Enhances usability for visually-impaired as well as
non-impaired
 Easily added to existing touchscreen devices, no
additional hardware required
Goal

33. 
 A personal computerwith 20 GBfree hard disk
space, 1GBRAMand PIV + processorcan be
efficient enough.
 The Windows Vista operating systemwas chosen
because the CCV package is highly supported in
Windows.
Computer Subsystem

34. 
 Many different platforms can be used to
develop multi-touch applications utilizing
TUIO events. Such platforms include:
 Adobe Flash
 Java
 C++
 Python
Application Development

35. 
 Personal Computing
 Graphics
 Audio Mixing
 Video Playing
 ComputerGaming
 Slide Presentations
……and many more!
APPLICATIONS