Quiz 2 Flashcards
Characteristics of Time
scale
ordinal (A before B before C)
discrete (points)
continuous (line)
Characteristics of Time
scope
point based (most common)
interval based
Characteristics of Time
arrangement
linear
cyclic
Characteristics of Time
viewpoint
ordered
branching
multiple perspectives
Characteristics of Time-Oriented Data
scale
quantitative (numbers)
qualitative (words)
Characteristics of Time-Oriented Data
frame of reference
abstract
spatial
Characteristics of Time-Oriented Data
kind of data
events
states
Characteristics of Time-Oriented Data
number of variables
univariate
multivariate
Mapping of time
- mapping time to space: static visualization, time and data in single coherent representation
- mapping time to time: dynamic representation, utilise physical dimension to convey time dependency of data
Categorisation on TimeViz Browser
data
- frame of reference: abstract vs. spatial
- variables: univariate vs. multivariate
Categorisation on TimeViz Browser
time
- arrangement: linear vs. cyclic
- time primitives: instant vs. interval
Categorisation on TimeViz Browser
vis
- mapping: static vs. dynamic
- dimensionality: 2D vs. 3D
Geospatial data
- describes objects with specific location in real world
- map spatial attributes to the two physical screen dimensions resulting in map visualizations
- map: world reduced to points, lines, and areas
Spatial phenomena
- point phenomena
- line phenomena: have length, but no width
- area phenomena: have both length and width
- surface phenomena: have length, width and height
Maps subdivided into:
Map types based on:
Properties of data:
- qualitative vs. quantitative
- discrete vs. continuous
Properties of graphical variables:
- points
- lines
- surface
- volumes
Map projections
mapping the positions on the globe (sphere) to positions on the flat surface
longitude: negative = western degrees
latitude: negative = southern
Cylinder projections
- preserve local angles
- conformal projections
- degrees of longitude and latitude usually orthogonal to each other
Plane projections
- azimuthal projections
- map to a plane that is tangent to the sphere with tangent point corresponding to the center point of projection
- some are true perspective projections
Cone projections
- map to cone that is tangent to the sphere
- degrees of latitude represented as circles around the projection center
degrees of longitude as straight lines emanating from center - designed to preserve distance from center to the cone
Point data
- discrete in nature, buy may describe continuous phenomenon
- discrete: occur at distinct locations
- continuous: defined at all locations
- smooth: data that change in gradual fashion
- abrupt: change suddenly
Dot maps
- place symbol at location
- quantitative parameter mapped to the size or color of the symbol
- problem of overlap or over plotting in highly populated areas
approaches for dense spatial data
- 2.5D visualization showing data points aggregated up to map regions
- individual data points as bars, according to their statistical value on a map
visualization of line data
- represent as line segments between pairs of endpoints specified by longitude and latitude
mapping of line data
- standard: data parameters mapped to line width, line pattern, line color, and line labelling
- start, end, and intersection points can be mapped to visual parameters (size, shape, color, labelling)
- lines do not need to be straight