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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
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?
Space – position
Relative horizontal order
Relative height
Space – relative size
Relative size among objects
Relative size among areas (figure / ground)
When are smaller objects closer to the viewer?
Space – familiar size
Size perception based on familiarity
What happens when relative and familiar sizes conflict?
Space – shape
Skewed shaped according to linear perspective
How do we discern unknown shapes from their orientation?
Space – Interposition
Occlusion (overlap)
Translucency (< 100% transparency)
When are object edge lines needed when are they not?
Space – Edge interpretation
Orientation & depth
Illumination & reflectance
What happens when there is no physically possible interpretation?
Space – colour
Relative saturation (chroma contrast)
Relative lightness (luminosity contrast)
Does colour / luminosity constancy affect space perception?
Space – convergence of parallels Linear perspective projection
Brunelleschi, Santo Spirito church, 1436
Space – texture
Texture gradient
Gustave Caillebote, Paris Street: Rainy Day
Space – lighting (shadows)
Shadows
diffuse shading
cast shadows
Space – lighting (highlights)
Highlights
Space – lighting (reflections)
Reflections
Space – focus
Depth of focus
Why does video not look as 3D as film (look at DOF)?
Space – accommodation
Changing eye lens size in order to focus
Space – accommodation
Lens accommodation in the eye
Why does accommodation not destroy 3D on 2D illusion?
Space – convergence
Convergence of eyes
Are there problems of convergence with 2D computer displays?
Space - stereopsis
Binocular disparity and fusion of images
What does fusion do to one’s depth perception?
Space – kinetic
Use of body enhanced depth perception
What happens to space perception if you don’t move at all?
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 can’t be experienced
Time – snapshot
A point in time with a history and future
Dust clouds near North African deserts
Time – diagrammatic
Vector map - movement, velocity, direction and path in time
Vector fields displaying fluid movement
Time – time series graphs
Time series (plotted X-Y graphs)
An image embedded into sound (sonogram)A flux of x-rays plotted against time
Time – sequence
Succession of snapshots
When does motion become fluid and flicker unnoticeable?
Hydrogen atom superposition of 6 eigenstates
Time – narrative & symbolic
Jerusalem 3000: Three Millennia of History
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
Colour – physics
Electromagnetic radiation
Why do we not see other frequencies of the EM spectrum?
Colour – Colorants
Pigments and dyes absorb & reflect different frequencies
What is the real colour of an object (how to measure)?
Colour – illumination
Illumination has a spectral distribution
What is ”daylight” and what is its colour temperature?
Colour – illumination intensity
Light intensity affects colour vision!
How can you calibrate displays if intensity affects colour vision?
Colour – perception
Perception = object properties + illumination properties (both global and local) + perceiver properties
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?
Colour – attention
Colour guides visual attention (pre-attentive)
What other pre-attentive vision properties are there?
Colour – motion Colour can cause apparent motion
Colour - categorisation
Various colour models for diff. purposes
Munsell NCS
Why don’t we define colours via their spectral distribution?
Colour – emotion
Colour’s 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?
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