Work Hours
Everyday: 北京时间8:00 - 23:59
LECTURE 8
GEOVISUALISATION 2
Davood Shojaei
Slide courtesy Dr Katerina Pavkova
GEOM90007
▪ Visual thinking
▪ 2D representations of 3D
▪ Virtual Reality
▪ Augmented Reality
▪ Mixed Reality
OVERVIEW
GEOM90007
Referential connections between visual information and verbal or textual information
Dual coding theory (Paivio, 1987)
▪ Logogens
Mental representations of basic language information, although not the sounds of
the words. Logogens provide support for reading and writing, understanding and
producing speech, and logical thought.
▪ Imagens
Mental representations of basic visual information. Imagens are objects, natural
groupings of objects, and whole parts of objects (for example, an arm), together
with spatial information about the way they are laid out in a particular
environment, such as a room
VISUAL THINKING FOR EDA (Ware, 2004)
Image: Ware (2004) GEOM90007
VISUAL THINKING
GEOM90007
Depth cues
▪ The visual world provides many different sources of information about 3D space
These sources are usually called depth cues
▪ Multiple cues are OK, the brain is very flexible in weighing evidence from the different
depth cues
THREE-DIMENSIONS
GEOM90007
Monocular depth cues o Perspective • Size gradient • Texture gradient • Linear perspective o Occlusion related • Occlusion • Cast shadows o Other • Depth of focus • Aerial perspective • Shading • Motion
THREE
-DIMENSIONS
GEOM90007
Arise from relative changes in geometry
▪ Objects vary in size on the picture plane in inverse proportion to their distance
▪ Similar triangles in eye
Image: Ware (2004)
Ray tracing
PERSPECTIVE CUES
GEOM90007Images: Ware (2004)
Size gradients
▪ Same object at a distance appears
smaller
Texture gradients
▪ Texture elements become smaller with distance
Linear perspective:
▪ At least two parallel lines
converge to a single point
PERSPECTIVE CUES
GEOM90007
Data Mountain (1998)
http://dl.acm.org.ezp.lib.unimelb.edu.a
u/citation.cfm?id=288596
Use of perspective to show more information
2D vs. 3D virtual environments (2002, 2003)
http://dl.acm.org.ezp.lib.unimelb.edu.au/citatio
n.cfm?id=503413
Source: Cockburn and McKenzie (2002)
PERSPECTIVE USER INTERFACE
GEOM90007
TIME PROCESSING IN 3D
“3D effects make no difference to
the effectiveness of spatial
memory” (Cockburn and
McKenzie, 2002)
Source: Cockburn and McKenzie (2002)
GEOM90007 Images: Brunnelleshi (1415)
Source: http://www.op-art.co.uk/history/perspective/
Source: http://www.op-art.co.uk/history/perspective/
Beware using junk!
Curvilinear
perspective
(fish eye)
OTHER PERSPECTIVE CUES
GEOM90007
Two techniques result in a ‘depth hierarchy’ – valuable for design
▪ Occlusion
▪ Cast shadows
OCCLUSION RELATED
GEOM90007Image: Vitrite http://vitrite.vanmiddlesworth.org/vitrite/shot-full.png
Images: Ware (2004)
If one object overlaps or occludes another, it
appears closer to the observer (Ware, 2004)
Partial occlusion occurs when one object is
transparent/translucent
▪ Be careful however!*
OCCLUSION
GEOM90007
An indirect depth cue used to indicate height above a plane
▪ Very effective at small heights
▪ Very confusing at large heights with many shadows
Images: Ware (2004)
SHADOWS
GEOM90007
Physical movement to bring images of objects into sharp focus on the fovea
- distant objects out of focus, closer ones in focus
Images: Ware (2004)
OTHER CUES
Depth of focus
GEOM90007
Simulates the effect of atmospheric particles
absorbing light
Closer objects appear brighter (with higher
contrast), sharper and more saturated in colour
than objects further away
Can be artificially created using ‘atmospheric
depth’
Images: Wikimedia Commons
(Ortega et al., 2016)
Distant objects appear
blurry and more blue
AERIAL PERSPECTIVE
GEOM90007
Shading can be used to indicate a shape that may have affordances
Can be useful to signify where an interaction can occur
e.g., buttons and widgets such as sliders
More information: http://dspace.mit.edu.ezp.lib.unimelb.edu.au/bitstream/handle/1721.1/6885/AITR-232.pdf?sequence=2 Images: Apple iCal
SHADING
GEOM90007
A velocity gradient is applied to objects to represent varying distances
Example: http://vimeo.com/50672419
Image: Ware (2004)
MOTION PARALLAX
GEOM90007
MOTION PARALLAX
http://mashable.com/2012/04/28/google-maps-parallax/#ldYYhzEI_mqR
GEOM90007
The 3D structural form of an object can be perceived in 2D when the object is moving
Example: A wire is bent into a complex 3D shape and then projected to a 2D plane
Example video: https://www.youtube.com/watch?v=RrX2yTGJ6N0
MOTION KINETIC
GEOM90007
Binocular depth cue
o Stereoscopic depth
o Binocular disparity
o Simulated depth cues
REPRESENTING THREE-DIMENSIONS
GEOM90007
Created from the fusing of two overlapping images called
stereopsis
The difference between the two images is called binocular
disparity
Vergence angle 𝜃 (convergence, divergence)
Approximately 10-20% of the population has stereo blindness
Binocular rivalry occurs when images can not be fused
Image: www.forbestvision.com
𝜃
STEREOSCOPIC DEPTH
GEOM90007
Image: Ware (2004)
Real World
A normal process arising from physical depth
Display
MagicEye or Stereoscopy
STEREOSCOPIC DEPTH (disparity)
GEOM90007
Frame cancellation
If an object moves towards the edge of the display, it may become occluded in
one image collapsing stereo, creating binocular rivalry
Distance variation
The stereoscopic depth cue is most useful for 30 meters or less from the viewer.
Beyond this, disparities are too small to be resolved. May be optimal for objects
held roughly at arm’s length.
Stereo blindness
Approximately 10-20% of the population
PROBLEMS CREATING STEREO
(Ware, 2004)
GEOM90007
STEREOSCOPIC VISION
https://www.youtube.com/watch?v=nKdUD8lIGJY
GEOM90007
Image: Ware (2004)
STEREOSCOPIC DEPTH
GEOM90007
Drop Lines
A line is dropped from each data
point to the ground plane to assist
with depth perception.
Without these lines, only a 2D
judgment of spatial layout is
possible.
With the lines, it is possible to
estimate 3D position.
ARTIFICIAL CUES
(Ware, 2004)
GEOM90007
Proximity luminance covariance
Change colour of object depending
on distance from the viewpoint
Mirrors atmospheric depth
ARTIFICIAL CUES
(Ware, 2004)
GEOM90007
A general theory of space perception should make it possible to determine which depth
cues are likely to be most valuable
Unfortunately, there is no single, widely accepted unifying theory of space perception.
COMBINING CUES
(Ware, 2004)
GEOM90007
Scene parameters - Camera settings
- Lightings and illumination
- Shading and shadows
- Atmospheric and Environmental effects
- …
Considerations - Position, size, orientation > Not suitable (?)
- Shape variable > Level of detail (LoD)
- Brightness > Good (?)
- Colour, texture > Excellent (?)
- Motion > Further research required
More reading:
http://icaci.org/files/documents/ICC_proceedings/ICC2015/papers/31/243.html
Careful not to change the
object’s meaning!
VISUALISING 3D SPATIAL OBJECTS
GEOM90007
Virtual Reality (VR) and beyond
GEOM90007
A fully immersive, interactive experience generated by a computer (Ryan, 2015)
Key components:
- Immersion
- Interactivity
Typically three (or four) dimensions, 360° view.
Hardware + Software dependent
VR
GEOM90007 - Immersion
a. Physical
b. Psychological (emotional)
c. Cognitive
Presence
Real time and space ‘fade’ into the background of consciousness
Flow
Intrinsically motivating, energized focus, pleasurable, rewarding
VR
GEOM90007 - Interactivity
Dialogues for control in virtual environments (VE)
e.g., walking or flying
Low visual latency (instantaneous system feedback)
VR
GEOM90007 - Head in jar
Headseat tracking only
High resolution OLED per eye
Examples: Standard Oculus Rift, Samsung Gear VR - Room-scale
Headset + body tracking
Greater interactivity using tracked controllers
More immersive, as you can wander around in an area
Example: HTC Vive
CURRENTLY TWO TYPES OF VR
GEOM90007
▪ Nausea
▪ Oculomotor problems
▪ Disorientation
Focus for designers: - Accommodation-vergence conflict (e.g., eye strain)
- Perception-proprioception issues (e.g., fast VE)
“In natural vision, binocular disparity and focus cues provide
comparable signals about object distance… These two
cues are involved in depth and distance perception.
In stereoscopic displays, focus cues are, however, inconsistent with the displayed
pattern of disparity because they signal a flat object”
CYBERSICKNESS
GEOM90007
Perception-proprioception issues
During almost all natural forms of self-motion, there are several sensory systems that
provide redundant information about the extent, speed, and direction of egocentric
movement, the most important of which include dynamic visual information
Self-motion perception is critical
https://www.ncbi.nlm.nih.gov/books/NBK92853/
VR
GEOM90007
Classic CAVEs are virtual-reality rooms with stereoscopic 3D computer graphics rearprojected onto the walls and down-projected onto the floor
CAVE2
https://www.evl.uic.edu/entry.php?id=2016
When exploring big data sets, understanding context and purpose is key when thinking
about interaction
VIRTUAL ENVIRONMENTS (VE)
GEOM90007
Angkor Wat
https://www.youtube.com/watch?v=4kU1TSLkMEk
APPLICATIONS
GEOM90007
AUGMENTED REALITY (AR)
Augmented reality is an interactive
experience by superimposing the
virtual objects on the real world.
GEOM90007
MIXED REALITY
https://docs.microsoft.com/en-us/windows/mixed-reality/discover/mixed-reality
GEOM90007
EXAMPLE
https://www.youtube.com/watch?v=_xpI0JosYUk
GEOM90007
MIXED REALITY DEVICES
Source: wired.com
Source: nreal.ai
GEOM90007
Self-contained holographic computer
Electronic input:
IMU, cameras, microphones, light sensors
Spatial mapping
Virtual objects interact with the real world
Human input: Gaze, gestures, voice/sounds
Example: https://www.youtube.com/watch?v=BMW2Pe6j6Bk
MICROSOFT HOLOLENS
GEOM90007
▪ Visual thinking
▪ 2D representations of 3D
▪ Virtual Reality
▪ Augmented Reality
▪ Mixed Reality
SUMMARY
Thank you!
