mapping. maps maps can depict visible surface features (towns), underground features (subways), and...
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Mapping
Maps
Maps can depict visible surface features (towns), underground features (subways), and abstract features (political boundaries)
Not possible to accurately represent round Earth on flat surface
Spatial concepts on maps—distance, direction, density, diffusion, linkage, flow, arrangement, accessibility
Latitude
Equator marks the zero degree parallel and is fixed by the laws of nature
Sailors measured latitude by length of day, height of sun, or known guide stars
Angle measured north or south from equator from 0° to 90°
Chicago--42° N
Longitude
Prime Meridian location is a political decision—Royal Observatory at Greenwich, England
Longitude measured by time—each hour’s time difference between ship and home port indicated 15 degrees
Intersect parallels at right angles Measured east or west 0° to 180° New York City--74° W
Minutes and Degrees
Basic latitude/longitude is degreeEach degree is divided into 60 minutesEach minute is divided into 60 secondsFor more precision on a location, specify
minutes or even secondsSometimes degrees are written as
decimals (36º 34.521 N)
Map Scale
Relationship between distance on the map and distance on the ground
Usually written as a fraction or ratio1:10,000 or 1/10,000 (1 inch of
measurement on the map equals 10,000 of same units on ground)
1 to 24,000 scale
1 to 100,000 scale
Map Scales (from USGS.com)
1 to 250,000 scale
Orientation
Never Eat Soggy WafflesNorth, East, South, West
Can use clock for directional reference “Dolphins at 1:00”
Good Map Elements (DOGSTAILS)
Date—when map was made Orientation—directions Grid—locates places on map Scale—map distance Title—what, where, when Author—who made map Index—map address of places Legend—what the symbols mean Sources—basis for map information
Map Types
Reference Political Physical Topographic Satellite
Thematic Choropleth Cartograms
Map Problems
When the National Geographic Society came out with it’s sixth Atlas edition, it contained approximately 10,000 changes, and was already out of date when it went for sale
Countries argue over namesKorea: East SeaJapan: Sea of Japan
Why Maps Lie
Cartographers are not licensed Maps distort reality Single map is one of large number of maps
that could be produced from same data Flat map stretches some distances and
shortens others Simplification Generalization
Common Map Errors
Based on incompatible sourcesMisspelled place-namesGraytone symbols changed by poor
printingCompiled from other mapsMap drafters having fun and including
fictitious townsInternational data based on inconsistent
definitions
Globe v. Map
Peel an orange into four equal pieces and lay the pieces side by side on a flat surface. Observe how the landmasses fit together.
Why we have different maps
Distortion exists with flat maps so cartographers use different projections to preserve selected properties (shape, size, distance, direction)
Map Projections
Mercator Projection
Good for navigation at sea because of straight lat/long lines
Renders Greenland as large as South America (yet 1/8 of size)
Flemish cartographer (1500s)
Map Projections
Robinson Projection
Accurate depiction of continent’s sizes and shapes
Distortion greatest at poles
Map Projection
J. Paul Goode (1923) Homolosine Equal-Area Projection Less distorted land masses by giving up continuous oceans
Map Projection
ConicBest for showing one section of Earth
without much distortion
Map Projection
PolarUsed mostly to show one hemisphere at
a timeAccurate for distance
and direction