spatial structures Flashcards
(23 cards)
core concepts
mapping data using location or spatial context to reveal geographic patterns
types of maps
base map
thematic map
base map
underlying geographic space
thematic map
overlaid data (social, political, scientific)
maps timelines
First thematic maps in 1700s.
Charles Dupin (1826):
First choropleth map.
John Snow (1854): Cholera outbreak
spatial epidemiology.
map design elements
projection
scale
symbolization
project
flattening the globe (affects accuracy
scale
level of detail (1:10,000 = large scale)
symbolization
matching data to visual forms
projection types
mercator (conformal)
equal area
robinson
mercator (conformal)
Navigation (preserves angles)
Equal-area (e.g. Mollweide)
Density comparisons
Robinson
Balanced distortion (compromise projection)
data types
Nominal
Categories (e.g. city names)
Ordinal
Rankings (e.g. small → large)
Quantitative
Measurable (e.g. population size)
Discrete
Cities
Continuous
Temperature
Visual Encoding (Symbolization)
marks
variables
clarity
positoning
marks
points, lines, areas
variables
Size, color hue/value/saturation, shape, orientation, texture.
clarity
Resolution, crispness, transparency.
positioning
Important for legibility and comparison.
Graphical Methods
Dot Distribution Maps: Show density (one dot = X people).
Graduated Symbols: Symbol size = data value.
Choropleth Maps: Shaded areas show intensity.
Isopleth/Isometric: Continuous data contours.
Flow Maps: Movement (migration, goods).
Cartograms: Area size scaled to data.
Visual Perception & Bias
Weber’s Law / Stevens’ Law: Perceived difference isn’t linear.
Be aware of visual illusions and label clarity.
Don’t mislead with symbol size or distorted areas.
