Space, Time

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Space, Time Colour in Visualisation

• Space
• Cues position, size, overlay, colour,
  perspective, texture, lighting, focus,
  accommodation, convergence, stereoscopy. 3D on
  2D. Semantic spaces
• Time
• Snapshot, vectors, time series (graphs),
  animation, multi-layered
• Colour
• Physics, colorants, illumination, perception,
  attention, motion, categorisation, emotion

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Space overview

• Real space (3D)
• Pictorial or illusory space
• Space perception active, supporting action
• Visualisation of 3D space on 2D based on depth
  cues

(Why) is our perception of space three
dimensional?
3
Space position

• Relative horizontal order
• Relative height

4
Space relative size

• Relative size among objects
• Relative size among areas (figure / ground)

When are smaller objects closer to the viewer?
5
Space familiar size

• Size perception based on familiarity

What happens when relative and familiar sizes
conflict?
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Space shape

• Skewed shaped according to linear perspective

How do we discern unknown shapes from their
orientation?
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Space Interposition

• Occlusion (overlap)
• Translucency (lt 100 transparency)

When are object edge lines needed when are they
not?
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Space Edge interpretation

• Orientation depth
• Illumination reflectance

What happens when there is no physically possible
interpretation?
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Space colour

• Relative saturation (chroma contrast)
• Relative lightness (luminosity contrast)

Does colour / luminosity constancy affect space
perception?
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Space convergence of parallels

• Linear perspective projection

Brunelleschi, Santo Spirito church, 1436
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Space texture

• Texture gradient

Gustave Caillebote, Paris Street Rainy Day
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Space lighting (shadows)

• Shadows

diffuse shading
cast shadows
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Space lighting (highlights)

• Highlights

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Space lighting (reflections)

• Reflections

15
Space focus

• Depth of focus

Why does video not look as 3D as film (look at
DOF)?
16
Space accommodation

• Changing eye lens size in order to focus

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Space accommodation

• Lens accommodation in the eye

Why does accommodation not destroy 3D on 2D
illusion?
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Space convergence

• Convergence of eyes

Are there problems of convergence with 2D
computer displays?
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Space - stereopsis

• Binocular disparity and fusion of images

What does fusion do to ones depth perception?
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Space kinetic

• Use of body enhanced depth perception

What happens to space perception if you dont
move at all?
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Time - overview

• Normative time (seconds, minutes, hours)
• Experienced time (psychological, real life)
• Implied or imaginary representation of time (on a
  2D surfaces)
• Visualisation concerned with implied time and
  different representations of time
• Visualisation can offer insights into normative
  time which cant be experienced

22
Time snapshot

• A point in time with a history and future

Dust clouds near North African deserts
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Time diagrammatic

• Vector map - movement, velocity, direction and
  path in time

Vector fields displaying fluid movement
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Time time series graphs

• Time series (plotted X-Y graphs)

A flux of x-rays plotted against time
An image embedded into sound (sonogram)
25
Time sequence

• Succession of snapshots

Hydrogen atom superposition of 6 eigenstates
When does motion become fluid and flicker
unnoticeable?
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Time narrative symbolic
Jerusalem 3000 Three Millennia of History
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Colour overview

• Light is electromagnetic radiation
• Colour is a perceptual property of light
• Light wavelengths do not map directly to colours
• Colour of an item is a combination of item,
  lighting and viewer characteristics
• Human colour vision is corrective, can be fooled
  and has strong emotive impact

28
Colour physics

• Electromagnetic radiation

Why do we not see other frequencies of the EM
spectrum?
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Colour Colorants

• Pigments and dyes absorb reflect different
  frequencies

What is the real colour of an object (how to
measure)?
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Colour illumination

• Illumination has a spectral distribution

What is daylight and what is its colour
temperature?
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Colour illumination intensity

• Light intensity affects colour vision!

How can you calibrate displays if intensity
affects colour vision?
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Colour perception

• Perception object properties illumination
  properties (both global and local) perceiver
  properties

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Colour - deficiency

• Deficiency in separating hues

Original
Colour deficient simulation (orig)
Corrected
Colour deficient simulation (corrected)
What is normal colour vision if everybody sees
differently?
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Colour attention

• Colour guides visual attention (pre-attentive)

What other pre-attentive vision properties are
there?
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Colour motion

• Colour can cause apparent motion

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Colour - categorisation

• Various colour models for diff. purposes

Munsell
NCS
Why dont we define colours via their spectral
distribution?
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Colour emotion

• Colours emotive impact is relative
• Culture
• Size in visual field
• Saturation
• Surrounding colours
• Personal differences
• Genre
• Etc.

Why does colour have such a potential emotional
impact?
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Summary

• Space, time and colour are related
• Visualization is about sensing, decoding and
  representing with space, time colour
• Many things in vision unknown
• Opportunities for research and experiments