Week 4- Geovisualisation Flashcards
Five steps of cartographic process
- distribution of phenomenon
- purpose of the map intended audience
- Collect data for mapping
- design and construct map
- can readers understand it
Conventional model: _____-centred
cartographer-centered
GIS information communication: ___-centred
user
Bias in Maps
- not neutral (reflect the dominant power of the time, i.e rome is centre of the world/political boundaries)
- Map projection (distorted my mercator, robinson etc)
- Data accuracy issues
- Human errors (i.e on screen digitising incorrectly)
types of data representing cartographic features
Both vector and raster:
- point (nominal: town, ordinal: town size)
- line (nominal: river, ordinal: type of road, Interval: contours)
- polygon/area (nominal: lake, interval: Elevation)
Thematic maps
- Illustrate the spatial structure, pattens and interrelationships rather than just geographical phenomena.
Types of thematic maps
- Quantitative map (spatial characteristics of numerical data, e.g population, income)
- Qualitative map (e.g location of oil fields, national parks)
Data classifications
- equal interval (divides range into equal-sized classes)
- quantile break (each class contains an equal number of features)
- Natural breaks (Jenks): natural groupings in data
- Geometric interval: breaks in geometric progression.
“cartographic design is the art, science and technology of map making” explain
- art: creative and effictive with colour choice or symbology to best display data
science: ensure accurate data that is correct
technology: skilled user of digital tools.
overall: intriguing
Map Design Principles
- Legibility
- Visual contrast
- Figure-ground organisation
- Hierarchical structure.
Legibility
e. g branches on a tree symbol is too intricate
e. g squashed contour lines
Contrast
e.g remarkably different road symbols to notice difference.
Figure-ground contrast
e.g greyscale either land or sea to distinguish difference.
Map Layout
- No single standard to follow
- asthetics or symmetry of all information on map
- all basic map elements
Digital mapping do’s and don’t’s
- don’t assume defult software setting is appropriate
- use graphical scale rather than verbal/ratio scale
- be a susceptive map reader
3D model for two or more variables
e.g service capacity of GPs in the area + patient distribution + transport routes
when to use Equal interval
when data is evenly distributed and want to emphasize the difference between the features
when to use jenks
when data is unevenly distributed
when to use quantile classification
when evenly distributed
when to use geometric
has geometric sequence based on a multiplyer
Lying with maps
- Inappropriate classification of data may hide meaning patterns and anomalies, or give misleading information.
