location, location, location. two measurements define location on globe measured in degrees from a...
TRANSCRIPT
Location, Location, Location
Two measurements define location on globe• Measured in degrees from a starting point
Latitude• Distance north or south of equator• North also designated as positive
Longitude• Distance east or west of a starting meridian• Meridian: line running from pole to pole• Prime meridian: through Greenwich, England• Link
Starting point: Equator!
Angular distance from equator measures latitude
Starting point: Prime meridian
Angular distance east or west of prime meridian
Globe is a model of Earth, showing locations of land and water
Great circle: Map is a flat representation of part of
Earth’s surface Chart is a flat representation of ocean
or air Both maps and charts have distortion
Projections are ways of transferring Earth structures/locations onto a flat map
Different projections are used for different purposes
Projections always create some sort of distortion
Medieval European T-O Map. In medieval Europe one of the most common forms of rendering the earth was the mappae mundi of which more than a thousand have survived. The T-O map is one kind of mappae mundi. The T-O image reproduced here comes from the encyclopedia of knowledge produced by Isidore, Bishop of Seville, in 630 A.D., and was printed in Augsburg in 1472.
The greatest "inventor" of sixteenth century Europe was map maker Gerhardus Mercator whose 1569 summary map, publicized by the learned Richard Hakluyt in his Principal Navigations, Voyages and Discoveries of the English Nation (London: 1589), liberated cartography from dependence on Ptolemy, and included a projection that allowed navigators to understand the coasts of the New World.
These maps silently promoted a Eurocentric view that privileged the Western image. Generations of European and American students have been indoctrinated with the glories of nationalism and colonialism through this map.
no matter how the earth is divided up, it can not be unrolled or unfolded to lie flat (undevelopable shape).
PROJECTIONSPROJECTIONS
(a) Azimuthal (gnomonic) (b) Cylindrical (c) Conic
Views of projected surfaces
ConicalConical
Globe sits under a cone, touching along pre-selected line of latitude
Projection developed by cutting cone lengthwise and unrolling
Distortion greatest at latitudes distant from where cone ‘touches’
PROJECTION CLASSIFICATION
PROJECTION CLASSIFICATION
ConicalConical
PolyconicPolyconic – envelopes globe with an infinite number of cones, each with its own standard parallel
PROJECTION CLASSIFICATION
PROJECTION CLASSIFICATION
CylindricalCylindrical
projected onto a cylinder which is also cut lengthwise and unrolled
PROJECTION CLASSIFICATION
PROJECTION CLASSIFICATION
Cylindrical DistortionCylindrical Distortion
projection of the entire world, significant distortion occurs at the higher latitudes
parallels become
further apart and poles
can not be seen
PROJECTION CLASSIFICATION
PROJECTION CLASSIFICATION
Cylindrical DistortionCylindrical Distortion
sizes of Greenland vs. Africa
Mercator Projection True size
PROJECTION CLASSIFICATION
PROJECTION CLASSIFICATION
Planar/AzimuthalPlanar/Azimuthal portion of earth’s surface is transformed from a
perspective point to a flat surface
PROJECTION CLASSIFICATION
PROJECTION CLASSIFICATION
MercatorMercator
cylindrical, conformal projection
angular relationships are preserved parallels and
meridians appear as straight lines
parallels are farther apart with increased distance from equator
COMMON PROJECTIONSCOMMON PROJECTIONS
Polar StereographicPolar Stereographic
directions are true from center point
conformal projection: over a small area, angles in the map are the same as the corresponding angles on Earth's surface
meridians are straight and radiating; parallels are concentric circles
shows only one hemisphere
COMMON PROJECTIONSCOMMON PROJECTIONS
RobinsonRobinson
developed to minimize appearance of angular and area distortion
distorts shape, area, scale and distance in an attempt to balance errors of projection properties
COMMON PROJECTIONSCOMMON PROJECTIONS
size of an object on a map compared to the actual object on the ground
distance
distance
ground
mapscalemap
may not be the same in all directions from a point depending on projection used
SCALE TYPESSCALE TYPES
Verbal scale
describes the scale in words
i.e. “one centimeter represents one kilometer”
commonly found on popular atlases and maps
Visual scale (bar scale or graphic scale)
graphically illustrates relationship between map distance and ground distance.
one end can be divided
most common
remains correct if reduced or enlarged
SCALE TYPESSCALE TYPES
Visual scale (bar scale or graphic scale)
SCALE TYPESSCALE TYPES
Representative Fraction (RF)
ratio (proportion) between map distance to earth distance
i.e. 1:50,000
most versatile; not tied to any specific units
SCALE TYPESSCALE TYPES
large scale: show a small area with a large amount of detail.
small scale: show a large area with a small amount of detail
all relative
LARGE VS SMALL SCALE
LARGE VS SMALL SCALE