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PerceptionPerception

Presented by: Meghan AllenPresented by: Meghan Allen

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PapersPapers

Perceptual and Interpretative Properties of Motion Perceptual and Interpretative Properties of Motion for Information Visualization, Lyn Bartram.for Information Visualization, Lyn Bartram.

Internal vs. External Information in Visual Internal vs. External Information in Visual Perception. Ronald A. Rensink. Perception. Ronald A. Rensink.

Level of detail: Varying rendering fidelity by Level of detail: Varying rendering fidelity by exploiting human change blindness. Kirsten exploiting human change blindness. Kirsten Cater, Alan Chalmers and Colin Dalton.Cater, Alan Chalmers and Colin Dalton.

Face-based Luminance Matching for Perceptual Face-based Luminance Matching for Perceptual Colormap Generation. Gordon Kindlmann, Erik Colormap Generation. Gordon Kindlmann, Erik Reinhard, and Sarah Creem. Reinhard, and Sarah Creem.

Large datasets at a glance: Combining Textures Large datasets at a glance: Combining Textures and Colors in Scientific Visualization. Christopher and Colors in Scientific Visualization. Christopher G. Healey and James T. Enns.G. Healey and James T. Enns.

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Perceptual and Interpretative Perceptual and Interpretative Properties of Motion for Properties of Motion for Information VisualizationInformation Visualization

Lyn BartramLyn Bartram

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MotivationMotivation

Current interfaces exceed the Current interfaces exceed the human’s perceptual capacity to human’s perceptual capacity to interpret theminterpret them

Motion is a perceptually rich and Motion is a perceptually rich and efficient display mechanism, but efficient display mechanism, but little research has been done to little research has been done to determine how well it can display determine how well it can display abstract dataabstract data

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Difficulties in Difficulties in visualizing informationvisualizing information Large amount of data requires a lot of Large amount of data requires a lot of

screen real estate, as well as screen real estate, as well as coordination between multiple windowscoordination between multiple windows

Dynamic nature of data requires users Dynamic nature of data requires users to notice changesto notice changes

Some data appears in multiple parts of Some data appears in multiple parts of the visualization system, requiring the visualization system, requiring users to assimilate the ‘big picture’ in users to assimilate the ‘big picture’ in their headstheir heads

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Graphical Graphical representationsrepresentations Shape, symbols, size, colour and Shape, symbols, size, colour and

position are ‘mentally economical’position are ‘mentally economical’ But, as the amount of data we But, as the amount of data we

want to visualize increases and as want to visualize increases and as the size of the screen we are the size of the screen we are using increases, more attention using increases, more attention needs to be paid to improving needs to be paid to improving ‘information bandwidth’‘information bandwidth’

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MotionMotion

Can motion be used to encode abstract Can motion be used to encode abstract data?data?– Motion is perceptually efficient and is Motion is perceptually efficient and is

becoming more technologically practicalbecoming more technologically practical– Visual system is pre-attentively sensitive to Visual system is pre-attentively sensitive to

motion across the entire visual fieldmotion across the entire visual field– Humans can pre-attentively track up to five Humans can pre-attentively track up to five

objects in motion at the same timeobjects in motion at the same time– By nature uses very little extra screen spaceBy nature uses very little extra screen space– Can be ‘layered’ with existing Can be ‘layered’ with existing

representations to increase the representations to increase the dimensionalitydimensionality

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GroupingGrouping

Humans perceive groups when Humans perceive groups when they see multiple object moving they see multiple object moving in the same mannerin the same manner– This could be useful for denoting This could be useful for denoting

group membership for objects that group membership for objects that are not spatially closeare not spatially close

– Could be useful for temporal as well Could be useful for temporal as well as spatial groupsas spatial groups

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Future DirectionsFuture Directions

Conducting experiments into Conducting experiments into simple motion and types of simple motion and types of patterns for grouping and patterns for grouping and association cuesassociation cues

How can motion convey How can motion convey relationships such as dependency relationships such as dependency and causality?and causality?

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CritiqueCritique

Interesting ideaInteresting idea Builds well on information that is known Builds well on information that is known

about the human perceptual systemabout the human perceptual system

I am not convinced that motion is a I am not convinced that motion is a reasonable way of increasing displayed reasonable way of increasing displayed dimensionality.dimensionality.

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Internal vs. External Information in Internal vs. External Information in Visual PerceptionVisual Perception

Ronald A. RensinkRonald A. Rensink

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Human visionHuman vision

We often feel that we must have We often feel that we must have a strong internal representation a strong internal representation of all the objects we can seeof all the objects we can see

Several experiments have argued Several experiments have argued against thisagainst this

Attention is required to create a Attention is required to create a ‘stable object representation’‘stable object representation’

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Change blindnessChange blindness

Subjects have difficulty noticing Subjects have difficulty noticing the changes that are made the changes that are made between the imagesbetween the images

General phenomenon and can be General phenomenon and can be induced many waysinduced many ways

ExamplesExamples

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Coherence theoryCoherence theory

Low level proto-objects are Low level proto-objects are continually formed, without attention.continually formed, without attention.

Focused attention selects a small Focused attention selects a small number of proto-objects, based on a number of proto-objects, based on a feedback loop called a coherence feedback loop called a coherence field.field.

Proto-objects lose their coherence Proto-objects lose their coherence after focused attention is released.after focused attention is released.

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Coherence theoryCoherence theory

Changes will only be noticed if the objects is being attended at the time

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Virtual RepresentationVirtual Representation

Only create a detailed representation Only create a detailed representation of the object being attendedof the object being attended

If these detailed representations can If these detailed representations can be created whenever needed, the be created whenever needed, the scene representation will appear scene representation will appear “real” to the higher levels, but with “real” to the higher levels, but with huge computational savingshuge computational savings

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Triadic architectureTriadic architecture

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Implications for Implications for displaysdisplays How can we create visual output that How can we create visual output that

best match the type of information pickup best match the type of information pickup described in coherence theory? described in coherence theory?

We can determine the order in which We can determine the order in which aspects of a scene are attended to, and aspects of a scene are attended to, and use that information to select what to use that information to select what to renderrender

There are limits on what the user will There are limits on what the user will perceive, which is important if the change perceive, which is important if the change itself was an important part of the itself was an important part of the visualization visualization

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Visual transitionsVisual transitions

Humans may miss transitions, which Humans may miss transitions, which could be an advantage or a disadvantagecould be an advantage or a disadvantage

User interfaces could attempt to take User interfaces could attempt to take advantage of change blindness so that advantage of change blindness so that their transitions were invisibletheir transitions were invisible

Displays should minimize Displays should minimize – the number of dynamic events occurring in the number of dynamic events occurring in

the backgroundthe background– the number of saccadesthe number of saccades

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Attentional coercionAttentional coercion

Magicians have been using this Magicians have been using this for centuriesfor centuries

By controlling what people are By controlling what people are paying attention to you can paying attention to you can control what they seecontrol what they see

A coercive display could ensure A coercive display could ensure that important events are seenthat important events are seen

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CritiqueCritique

Good descriptions of the different Good descriptions of the different ways we visually perceive ways we visually perceive informationinformation

The figured aided my The figured aided my understanding of coherence theory understanding of coherence theory and triadic architectureand triadic architecture

I wanted to read about some real I wanted to read about some real examples of coercive displaysexamples of coercive displays

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Level of detail: Varying rendering Level of detail: Varying rendering fidelity by exploiting human fidelity by exploiting human change blindness. change blindness.

Kirsten Cater, Alan Chalmers and Kirsten Cater, Alan Chalmers and Colin DaltonColin Dalton

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MotivationMotivation

Most virtual reality environments Most virtual reality environments are too complex to be rendered in are too complex to be rendered in real timereal time

Change blindness can be Change blindness can be exploited to shorten rendering exploited to shorten rendering times without compromising times without compromising perceived qualityperceived quality

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Change blindnessChange blindness

‘‘the inability of the human eye to the inability of the human eye to detect what should be obvious changes’detect what should be obvious changes’

If attention is not focused on an object If attention is not focused on an object in a scene, changes to that object may in a scene, changes to that object may go unnoticedgo unnoticed

Occurs because our internal Occurs because our internal representation of the visual world is representation of the visual world is sparse and only contains objects of sparse and only contains objects of interestinterest

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Visual AttentionVisual Attention

Spatial acuity is highest at the Spatial acuity is highest at the centre of the retina, the foveacentre of the retina, the fovea

Visual angle covered by the fovea Visual angle covered by the fovea is approximately 2 degreesis approximately 2 degrees– Saccade: moving the next relevant Saccade: moving the next relevant

object into the focus of the foveaobject into the focus of the fovea

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BackgroundBackground

O’Regan et al.’s flicker paradigm, O’Regan et al.’s flicker paradigm, and mudsplash paradigmand mudsplash paradigm– Marginal interest vs. Central interestMarginal interest vs. Central interest

Peripheral VisionPeripheral Vision– Human eye only processes detailed Human eye only processes detailed

information from a small part of the information from a small part of the visual fieldvisual field

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ExperimentExperiment

24 images, aspects of the images 24 images, aspects of the images were labeled Central interest or were labeled Central interest or Marginal interestMarginal interest

Principles of the flicker and Principles of the flicker and mudsplash paradigms were used, mudsplash paradigms were used, but the image was rendered but the image was rendered differently each time instead of differently each time instead of using photographsusing photographs

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ExperimentExperiment

Rendering quality was a factorRendering quality was a factor– High resolution images took High resolution images took

approximately 18 hours to renderapproximately 18 hours to render– Low resolution images took Low resolution images took

approximately 1 minute to renderapproximately 1 minute to render

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ResultsResults

Subjects took significant amounts of Subjects took significant amounts of time to notice the changes in the imagestime to notice the changes in the images

Modified central interest aspects were Modified central interest aspects were found faster than modified marginal found faster than modified marginal interest aspectsinterest aspects

Subjects were much slower to recognize Subjects were much slower to recognize rendering changes compared to location rendering changes compared to location or presence changesor presence changes

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ConclusionsConclusions

Computational savings could be Computational savings could be dramaticdramatic

Inattentional blindness is the Inattentional blindness is the failure to see any unattended failure to see any unattended objectsobjects

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CritiqueCritique

‘‘Change Blindness occurs in Change Blindness occurs in computer graphics images as it computer graphics images as it does in real life’ – seemed does in real life’ – seemed obvious to meobvious to me

Didn’t give any specific guidelines Didn’t give any specific guidelines on how to exploit Change on how to exploit Change Blindness in software applicationsBlindness in software applications

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Face-based Luminance Matching Face-based Luminance Matching for Perceptual Colormap for Perceptual Colormap Generation. Generation.

Gordon Kindlmann, Erik Reinhard, Gordon Kindlmann, Erik Reinhard, and Sarah Creemand Sarah Creem

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LuminanceLuminance

Luminance is a very important aspect of Luminance is a very important aspect of visualization because it affects our visualization because it affects our perception of image structure and surface perception of image structure and surface shapeshape

3 issues with using luminance in 3 issues with using luminance in colormapscolormaps– Uncalibrated displaysUncalibrated displays– Lighting conditions of the room are unknownLighting conditions of the room are unknown– Yellow pigments can cause non-trivial Yellow pigments can cause non-trivial

differencesdifferences

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Luminance efficiency Luminance efficiency functionfunction Describes the sensitivity of the Describes the sensitivity of the

eye to various wavelengthseye to various wavelengths Many of the techniques to Many of the techniques to

measure the luminance efficiency measure the luminance efficiency function are based on matching function are based on matching

Goal is to create a task similar to Goal is to create a task similar to the minimally distinct border the minimally distinct border method that is easier for usersmethod that is easier for users

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MethodMethod

• One face appears ‘positive’ while the other appears ‘negative’

• Black is replaced by gray and white is replaced by a colour

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ExampleExample

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User studyUser study

Compared MDB to face based Compared MDB to face based luminance matchingluminance matching

No significant difference by task, No significant difference by task, but face based luminance but face based luminance matching was more precise than matching was more precise than MDBMDB

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Colormap generationColormap generation

Need to create Need to create the hues in the hues in between the 6 between the 6 that were that were matched by matched by interpolationinterpolation

Used data from Used data from the user study the user study averaged over all averaged over all participants and participants and trialstrials

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CritiqueCritique

Interesting ideaInteresting idea Succinctly explained the Succinctly explained the

background information and background information and related workrelated work

Well designed user study, with Well designed user study, with good hypothesesgood hypotheses

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Large datasets at a glance: Large datasets at a glance: Combining Textures and Colors in Combining Textures and Colors in Scientific Visualization. Scientific Visualization.

Christopher G. Healey and James T. Christopher G. Healey and James T. EnnsEnns

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ObjectiveObjective

To create a method to display To create a method to display complex and large data sets that complex and large data sets that encode multiple dimensions on a encode multiple dimensions on a single spatial pointsingle spatial point

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ExampleExample

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Bottom up vs. top Bottom up vs. top downdown Bottom up: the limited set of Bottom up: the limited set of

features that psychologists have features that psychologists have identified as being preattentiveidentified as being preattentive

Top down: attention is controlled Top down: attention is controlled by the task you are attempting to by the task you are attempting to performperform

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PexelsPexels

Multicolored perceptual texture Multicolored perceptual texture elements (pexels) are usedelements (pexels) are used

Pexels have differing height, density, Pexels have differing height, density, regularity and colorregularity and color

Goal: select texture and color Goal: select texture and color properties that allow for fast visual properties that allow for fast visual exploration, while minimizing exploration, while minimizing interactions between the visual interactions between the visual featuresfeatures

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ExperimentsExperiments

Can density, regularity and height Can density, regularity and height be used to show structure?be used to show structure?

How can we use the dataset’s How can we use the dataset’s attributes to control the values of attributes to control the values of each perceptual dimension?each perceptual dimension?

How much visual interference How much visual interference occurs between the perceptual occurs between the perceptual dimensions?dimensions?

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ExampleExample

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ResultsResults

Taller regions were identified very Taller regions were identified very quicklyquickly

Shorter, denser, and sparser targets Shorter, denser, and sparser targets were more difficult to identify than were more difficult to identify than taller targets, although some good taller targets, although some good results were still foundresults were still found

Background variation produced small, Background variation produced small, but statistically significant interaction but statistically significant interaction effectseffects

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ResultsResults

Irregular targets were difficult to Irregular targets were difficult to identifyidentify

Poor detection results for Poor detection results for regularity were unexpectedregularity were unexpected

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Perceptual ColorsPerceptual Colors

Designed experiments to select a Designed experiments to select a set of n colors such thatset of n colors such that– Any color can be detected Any color can be detected

preattentivelypreattentively– Every color is equally easy to identifyEvery color is equally easy to identify

Tested for the maximum number Tested for the maximum number of colors that can be displayed of colors that can be displayed simultaneously while satisfying simultaneously while satisfying the above requirementsthe above requirements

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ColorColor

Color distanceColor distance– Colors that are linearly separable Colors that are linearly separable

from one another are easier to from one another are easier to distinguishdistinguish

Color categoryColor category– Colors that are in different named Colors that are in different named

categories (such as purple and blue) categories (such as purple and blue) are easier to distinguishare easier to distinguish

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ExperimentExperiment

First experiment First experiment controlled color controlled color distance and distance and linear separation linear separation but not color but not color categorycategory

4 studies that 4 studies that displayed 3, 5, 7 displayed 3, 5, 7 and 9 colors and 9 colors simultaneouslysimultaneously

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ResultsResults

All targets were detected rapidly All targets were detected rapidly and accurately when 3 and 5 and accurately when 3 and 5 colors were displayedcolors were displayed

With 7 and 9 colors, the time to With 7 and 9 colors, the time to detect certain colors was detect certain colors was proportional to the display sizeproportional to the display size

Is this due to color categories?Is this due to color categories?

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Color category Color category experimentexperiment Subjects were asked to describe Subjects were asked to describe

colorscolors The amount of overlap between The amount of overlap between

the names was used to determine the names was used to determine ‘category overlap’‘category overlap’

Category overlap was a good Category overlap was a good indicator of performanceindicator of performance

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Texture and ColorTexture and Color

Do variations in pexel color affect Do variations in pexel color affect the detection of targets defined the detection of targets defined by height or density?by height or density?

Do variations in pexel height of Do variations in pexel height of density affect the detection of density affect the detection of targets defined by color?targets defined by color?

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ExamplesExamples

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ResultsResults

Background variation had no effect on Background variation had no effect on detection of color targets.detection of color targets.

Detection accuracy for height and Detection accuracy for height and density targets was similar to results density targets was similar to results from the texture experimentsfrom the texture experiments

Background variation in color had a Background variation in color had a small but statistically significant effectsmall but statistically significant effect

Denser and taller targets were easier Denser and taller targets were easier to recognizeto recognize

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Practical applicationsPractical applications

Visualizing typhoonsVisualizing typhoons– Windspeed (height)Windspeed (height)– Pressure (density)Pressure (density)– Precipitation (color)Precipitation (color)

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ConclusionsConclusions

Data/feature mapping must Data/feature mapping must match with the workings of the match with the workings of the human visual systemhuman visual system

Color distance, linear separation Color distance, linear separation and color category must all be and color category must all be considered when choosing colorsconsidered when choosing colors

Results were validated when Results were validated when applied to real world dataapplied to real world data

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CritiqueCritique

Thorough experimentsThorough experiments

Pexels only allow 3 dimensions to Pexels only allow 3 dimensions to be displayedbe displayed

No guidelines about how to map No guidelines about how to map your data to the representationsyour data to the representations

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BibliographyBibliography

Internal vs. External Information in Visual Perception. Ronald A. Internal vs. External Information in Visual Perception. Ronald A. Rensink. Proc 2Rensink. Proc 2ndnd Int. Symposium on Smart Graphics, pp 63-70, Int. Symposium on Smart Graphics, pp 63-70, 20022002

Large datasets at a glance: Combining Textures and Colors in Large datasets at a glance: Combining Textures and Colors in Scientific Visualization. Christopher G. Healey and James T. Scientific Visualization. Christopher G. Healey and James T. Enns. IEEE Transactions on Visualization and Computer Graphics Enns. IEEE Transactions on Visualization and Computer Graphics 5, 2, (1999), 145-167.5, 2, (1999), 145-167.

Face-based Luminance Matching for Perceptual Colormap Face-based Luminance Matching for Perceptual Colormap Generation. Gordon Kindlmann, Erik Reinhard, and Sarah Creem. Generation. Gordon Kindlmann, Erik Reinhard, and Sarah Creem. Proc. Vis 2002. Proc. Vis 2002.

Perceptual and Interpretative Properties of Motion for Perceptual and Interpretative Properties of Motion for Information Visualization, Lyn Bartram, Proceedings of the 1997 Information Visualization, Lyn Bartram, Proceedings of the 1997 workshop on New paradigms in information visualization and workshop on New paradigms in information visualization and manipulation, 1997, pp 3-7 manipulation, 1997, pp 3-7

Level of detail: Varying rendering fidelity by exploiting human Level of detail: Varying rendering fidelity by exploiting human change blindness. Kirsten Cater, Alan Chalmers and Colin change blindness. Kirsten Cater, Alan Chalmers and Colin Dalton. Proceedings of the 1Dalton. Proceedings of the 1stst international conference on international conference on Computer graphics and interactive techniques in Australia and Computer graphics and interactive techniques in Australia and South East Asia, 2003, pp 39-46South East Asia, 2003, pp 39-46