Output devices

Universidade de Aveiro

Departamento de Electrónica,

Telecomunicações e Informática

Interfaces Humano-Computador Beatriz Sousa Santos

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Put on your glasses!

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Less Conventional “Displays”

not only visual …

Graphics Displays

“A graphics display is a computer interface that

presents synthetic world images to one or several

users interacting with the virtual world.”

(Burdea and Coiffet., 2003)

• Personal displays:

- HMDs (VR/AR)

- Binoculars

- Monitor-based displays/active glasses

- Autostereoscopic displays

• Large volume displays:

–Workbenches

– Caves

– Walls, domes

–…

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Personal Displays

A graphics display that outputs a virtual scene destined to be

viewed by a single user. Such image may be monoscopic or

stereoscopic, monocular (for a single eye) or binocular (displayed

on both eyes).

• Head Mounted Displays (HMDs)

• 3-D Binoculars (hand supported)

• Auto-stereoscopic displays

(desk supported)

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Projector based

large-volume

displays

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• Workbanch-type displays

• CAVE type displays

• Wall-type displays

• Domes

http://www.mechdyn

e.com/cave2.aspx

https://www.tii.se/inside-

explorer-at-the-british-

museum

Graphics Displays

• Main technologies:

- LCD displays

- OLED displays

- Autostereoscopic displays: lenticular/barrier

- Projectors

• Other technologies: plasma, electrophorectic,

electroluminescent displays

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LCDs (Liquid Crystal Displays)

Layers in a LCD States of a LCD

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Colour LCD

White Yellow

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Plasma displays

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Colour plasma display

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CRTs, LCDs and plasma displays

CRTs (past)

Advantages

• Brightness

• Price

Disadvantages

• Volume, weight

• Consumption

LCDs

Advantages

• Volume, weight

• Consumption

Disadvantages

• Past: Price

(passive LCDs):

Brightness, angle

Plasma

Advantages

• Width

• Size

• Brightness

Disadvantages

• Price

• Comsumption

Electrophoretic displays: “e-paper”

• Form images by rearranging charged pigment particles applying an

electric field and reflect light like ordinary paper

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https://en.wikipedia.org/wiki/Electronic_paper

http://electrophoretic.com/site/index.php/electrophoretic-display

Commercial devices: Kindle, Nook, ...

• Reflect light like paper

• Very low consumption

• Very low refresh rate

• “Ghosting”

Not very interesting for interactive applications

(at least yet)

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Organic LEDs (OLEDs)

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OLEDs

• OLEDs allow displays:

• flexible

• more efficient

• brighter

than LEDs

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• Images provided by computer monitors are poor when compared to the real world

• It is amazing what we get from such simple devices

• Monitors have sevral limitations:

– Small range of intensities and colors

– Lack of focusing distance

– Small field of view

– ...

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Stereoscopic displays

Stereoscopic Vision

• Depth perception in mono images is based:

- on occlusion (one object blocks another from view)

- shadows

- textures

- motion parallax

(closer images appear to move more than distant ones)

(Burdea and Coiffet., 2003)

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Stereopsis

Stereo ="solid" or "three-dimensional“

opsis = appearance or sight

'binocular vision‘ , 'binocular depth perception' , 'stereoscopic depth

perception'

• Stereopsis is the impression of depth that is perceived when a

scene is viewed with both eyes by someone with normal binocular

vision

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• Binocular disparity is due to the different position of our two eyes

Projection plane

eyes

object

Right eye image Left eye image

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Projection plane

eyes

object (Hearn and Baker, 2002)

• Need to present two images of the

same scene

• The two images can be presented:

• at the same time on two displays

(HMD)

• time-sequenced on one display

(active glasses)

• spatially-sequenced on one

display (auto-stereoscopic

displays)

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Implications for Stereo Viewing devices

Left eye, right eye images

(Burdea and Coiffet., 2003)

Common ways to produce a 3D sensation

• Anaglyphs: two colored images and color coded glasses

(red/cyan(green))

• Two images with different light polarization and polarizing glasses

– Linear and circular

• Double frame-rate displays combined with LCD shutter glasses

• Autostereoscopic displays

– Parallax barrier and lenticular lens

• Head Mounted Displays (HMDs)

and “exotic displays”

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• All show the right image to the right eye and the left image

to the left eye!

• All these technologies provide:

– stereo parallax

• When combined with headtracking,

they can provide

– movement parallax

for a single viewer

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Voice synthesizers

• There are several types:

Digitized - concatenates recorded basic sounds

Synthesised – concatenates sounds generated with models

• There are several technical challenges due to the nature of human voice:

different pronunciation rules

meaning may be changed by intonation

differences in intonation reflect different moods

• The quality of a synthesizer implies much more than intelligibility

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Advantages:

When the user has:

• physical deficiency

• to move around

• hands and eyes busy

• Adverse conditions: low visibility, low O2, high Gs

Disadvantages:

• Is tiresome and uncomfortable

• Is transient (taxes STM)

• Implies lack of privacy

• May disturb other people

Examples:

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Some guidelines to use voice output

• Consider voice output as an alternative when the user must

move around, has hands and eyes busy

• Avoid voice output in open environments, when the privacy

and security are important issues and frequency of usage is

high

• Use approx. 180 words per minute

• When messages are not expected, start with non-critical words

that provide context

• Say first the goal and then the solutions

• Allow messages to be repeated

Virtual Reality Cerebral Aneurysm Clipping Simulation With

Real-Time Haptic Feedback

http://journals.lww.com/neurosurgery/Fulltext/2015/0

3002/Virtual_Reality_Cerebral_Aneurysm_Clipping.9.

aspx

Image tools:

A glimpse of the future? Interactive live holography

image-guided therapies for heart diseases (2013)

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https://www.youtube.com/watch?v=AIj2xEd

_z78

http://www.newscenter.philips.com/main/standard/news/pres

s/2013/20131028-Philips-and-RealView-Imaging-conclude-

worlds-first-study-to-evaluate-live-3D-holographic-imaging-

in-interventional-cardiology.wpd#.Um4h9hC3WwB

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• Technology shall not be used only because it is new!

• Independently from the type or state of the art of the input /

output devices it is necessary to understand their usability for

different types of users and tasks

Conclusion

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Main Bibliography

• Dix, A., J. Finley, G. Abowd, B. Russell, Human Computer Interaction,

3rd Ed.Prentice Hall, 2003

• B.Shneiderman.C.Plaisant.M.Cohen.S.Jacobs, Designing the User

Interface- Strategies for Effective Human-Computer Interaction, 5th

ed., Addison Wesley, 2009

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Other Bibliography

• Mann, S., “My ´’Augmediated’ Life, What I’ve learned from 35 years of

wearing computerized eyewear”, IEEE Spectrum, March, 2013, pp. 42-47

• http://electronics.howstuffworks.com

• http://en.wikipedia.org/wiki/Project_Glass

• http://www.lukew.com/ff/entry.asp?1720