Maps
Do you know what a map of the world looks like? Are you sure? How sure? Describe it
Map Grid Latitude /Longitude Tropics Equator Prime Meridian /International Date Line Latitude – smile Longitude – oh Head: north pole Tropic of Cancer:shoulders Waist: equator Knees: tropic of Capricorn Toes: south pole Arms straight up: prime meridian Facing back arms up: IDL 3
Gain a Day Skip a Day
Immediately to the left of the International Date Line, the date is always one day ahead of the date immediately to the right of the International Date Line. On the time and date codes shown below, note that Tonga and Samoa have the exact same time, but are actually one day apart, as Samoa is in the Western Hemisphere (to the east of the dateline) and Tonga is in the Eastern Hemisphere. In summary, travel west across the International Date Line and you will gain a day, travel east across it and you will lose a day.
All Maps should Have Cartographer Title Scale Key
Map projection is the way we fit earth’s three-dimensional surface onto flat paper or a screen
On a map, when lines of latitude and longitude cross what is the resulting angle?
http://www.progonos.com/furuti/MapProj/Normal/ProjInt/ProjStar/projStar.html
Pencils Down – The following information is for background knowledge only.
Map Projections Think of an transparent globe w/ an imagined light source inside What type of shadow would be cast?
Shadow cast would depend on light location… Gnomonic – light source at center Stereographic – light at point opposite of tangent of globe meeting map Orthographic – light source at infinity
Onto What do you project An azimuth is the angle formed at the beginning point of a straight line, in relation to the meridian
Position of the surface
The Math… Derivation of the Projection: Derivation of the Inverse: Just Kidding Derivation of the Projection: cosφ=dR⇒d=Rcosφ cosλ=p2d⇒p2=dcosλ=Rcosφcosλ sinλ=p1d⇒p1=dsinλ=Rcosφsinλ Derivation of the Inverse: d=∥p∥ cosλ=p2∥p∥⇒λ=cos-1(p2∥p∥) cosφ=dR⇒φ=cos-1(∥p∥R)
An Important Mathematical Result: The Most Common: Conformal (i.e., angles are preserved) Equal Area (i.e., areas are in constant proportion) Equidistant (i.e., distances are in constant proportion) An Important Mathematical Result: A single projection can not be both conformal and equal area
Polar Azimuthal Orthographic
Sinusodial Projection Retains property of equivalence
Equatorial Cylindrical Equal Area
Equatorial Cylindrical Conformal Mercator style
Conical Equal Area
Three sources of map distortion Map scale – most maps are smaller than the reality they represent. Map scales tell us how much smaller. Map projection – this occurs because you must transform the curved surface of the earth on a flat plane. Map type – you can display the same information on different types of maps.
Mercator Projection Conformal – displaying true shapes of individual features but exaggerating size
Equal Area Projection
Robinson Projection
Goode’s Projection
Peter’s Projection
The Peters Projection World Map is one of the most stimulating, and controversial, images of the world. When this map was first introduced by historian and cartographer Dr. Arno Peters at a Press Conference in Germany in 1974 it generated a firestorm of debate. The first English-version of the map was published in 1983, and it continues to have passionate fans as well as staunch detractors. The earth is round. The challenge of any world map is to represent a round earth on a flat surface. There are literally thousands of map projections. Each has certain strengths and corresponding weaknesses. Choosing among them is an exercise in values clarification: you have to decide what's important to you. That is generally determined by the way you intend to use the map. The Peters Projection is an area accurate map. http://www.petersmap.com/page2.html