Upload
willis-charles-hensley
View
216
Download
2
Embed Size (px)
Citation preview
Map of the Day
• Data: Terrorist Plots AND Drone Strike Locations in Yemen
• Goal: 1 map that shows both
• 2000-2012
• What does your map look like?
What’s the point?
• The Basic Principles of Symbolizing Phenomena
• The Congruence Principle
• Lots of ways to think about and differentiate geographic phenomena
• Different kinds of phenomena need different kinds of maps
Diagnose your data
• Different data require different visual treatments
• Build a visual structure that mimics the nature of your data’s structure
• Qualitative vs. Quantitative / Discrete vs. Continuous / Abrupt vs. Smooth
• Points, Lines, Polygons, Volumes
• Levels of Measurement
• Visual Variables
The thematic map
• Also called the “statistical map,” “single-topic map,” or the “special-purpose” map
• Less literal than a general-reference map
• Two groups of thematic maps: qualitative and quantitative
The 2 kinds of thematic maps
•Qualitative thematic maps
• Show the spatial distribution or location of kind
• Land use
• Soil types
• Languages
• Restaurants
• These maps are concerned with kinds, names, types (nominal data)
The 2 kinds of thematic maps
•Quantitative thematic maps
• Spatial aspects of numerical data
• Corn yield
• Per Capita Income
• Number of Tornadoes
• Population Density
• These maps are concerned with amounts, or quantities
• Can you tell the difference?
• Is the attribute a quantity or a quality?
Geographic Phenomena
•The things we want to map
•5 geometric models of geographic phenomena
•Differentiated by spatial dimensions
Spatial Arrangement of Data
•5 types of geographic phenomena
•differentiated by spatial dimensions
•Zero-dimensional – ?
•One-dimensional - ?
•Two-dimensional - ?
Spatial Arrangement of Data
• 5 types of geographic phenomena
• Separated by spatial dimensions
•Zero-dimensional – points
•One-dimensional - lines
•Two-dimensional – areas
•2.5-dimensional - ?
•Three-dimensional - ?
Point Phenomena
•Points have no spatial-extent: zero-dimensional
•Examples of geographic point data?
Point Phenomena
•Points have no spatial-extent: zero-dimensional
•Examples of geographic point data?
•Weather stations, oil wells, eagle nesting sites
•Location described by coordinates
•(X,Y)
•(X,Y,Z)
Linear Phenomena
•Lines have 1 dimension: length, but no width
•Examples of geographic lines?
•Borders between countries
•Flight lines
Linear Phenomena
•Lines have 1 dimension: length, but no width
•Examples of geographic lines?
•Borders between countries
•Flight lines
•Described by a series of coordinate locations
Areal Data
•2-dimensional in spatial extent: length and width
•Examples of geographic areas?
•Lakes, political areas…
•Described using a series of coordinates that close a region
Volumetric Phenomena
•2.5-Dimensional Phenomena
•1 x value, 1 y value, 1 z value
•Every x,y pair has a single value associated with it
•“A surface” – example: elevation
•3-Dimensional Phenomena
Volumetric Phenomena
• 2.5-Dimensional Phenomena
•1 x value, 1 y value, 1 z value
•Every x,y pair has a single value associated with it
• “A surface” – example: elevation
• 3-Dimensional Phenomena
•True 3-D data are multivalued
•Each x,y pair can have many z values
True 3-D phenomena
• 4 important values
1. X-value
2. Y-value
3. Z-value (height above or below)
4. Measured value of Phenomenon
True 3-D phenomena
• 4 important values
1. X-value
2. Y-value
3. Z-value (height above or below)
4. Measured value of Phenomenon
• The first 3 are locational coordinates, the last describes the attribute
• EXAMPLES?
How does map scale influence spatial
dimension?•Map Scale and cities?
•Map Scale and rivers?
•Models of geographic phenomena
•Reducing geographic realities to geometric primitives
Discrete Phenomena
•Occur at distinct location
•With space in between
•Examples: people living in a city – as points, space between
•Weather stations
•Restaurants
Continuous Phenomena
•Continuous phenomena are defined everywhere:
•Examples: elevation, air pressure, temperature, land cover
What things change abruptly?
•Tax rates
•Spending on public school students
•Number of postal employees
•# of electoral votes