# Geo 301 Midterm

 Map A spatial representation of the environment Cartographic map a graphic representation of the environment Egocentric direct experience Geocentric mentally orient yourself with respect to external environment Map Characterisitcs (Mapness)vertical or oblique view of the environmentdrawn to scaledrawn on a map projectiongeneralized and symbolized representation what makes maps popular? convenient to use simplify our surroundingsare credible documents have strong visual impact Thematic maps focus on specific subject and be organized Map Use process of obtaining useful information from one or more maps to help you understand the environment and improve mental map How does an image differ from a cartographic map? variable scalenot on a map projectiongeneralized?symbolized? Earth circumference 24,907 mi40,075 km Graticule Parallels and Meridians use to locate features by their coordinates Parallels (latitude)equally spaced east - west Meridians North - South lines (longitude) Numerical range of Latitude 0 degrees to 90 degreesSpacing = 69.2 mi. per deg. Numerical range of Longitude 0 degrees to 180 degrees Degrees, Minutes, Secs to Decimal Degrees Degrees + min/ 60 + seconds/3600 Spacing of meridians 69.2 mi/ deg. * cosine (latitude) Great Circle largest possible circle that could be drawn on the surface of the spherical earth Antipodal meridian 180 degree meridian opposite from prime meridian Quadrilaterals areas on earth bounded by equal increments of latitude and longitude Oblate Ellipsoide parallels are not spaced equally as on a sphere Geodetic latitude angle made by a line perpendicular to ellipsoid surface at the parallel and equator line is on large scale maps Geoid surface where gravity is the same as at mean sea level (MSL)elevation measure by geoid, but GPS uses ellipsoid Representative Fraction (RF) 1/x = map distance / ground distance Ways of specifying scale 1. RF 1:24,0002. Scale statement : one inch to 20,000 ft3. Scale bar Large Scale Maps Zoomed in Smaller RF Smaller Scale Maps Zoomed out Larger RF Calculating RF from a known terrestrial feature: 1 mi wide section of land = 1.01 in on map 1/x = 1.01in / (1 mi. * 63,360 in /mi) = 1.01 in / 63,360 inx = 63,360 in / 1.01 = 62,500 1:62,500 Calculate RF from reference material: 1:62,500 distance between roads 5.69 in and 7.42 in on your map 1/62,500 = 5.69 in1/x 7.42 inx = 62,500 = 5.69 in /7.42 in = 47,9001:47,900 Calculating RF from spacing of parallels and meridians: 2 parallels separated by 30 minutes of lat to be 4.37 inches apart on map 30 minutes of lat = .5 deg *69.2 mi/deg = 34.6 mi1/x = 4.37 in /34.6 mi = 4.37 in / (34.6 mi *63,369 in/mi)x = 34.6 mi *63,360 in/mi / 4.37 mi1:502,000 Map Projection geometrical transformation of the earths spherical or ellipsoidal Geometric Distortions on Maps continuitycorrespondence relationsdistanceareadirectionshapecompleteness Geoid project earths irregular surface topography onto a more regular imaginary surface. Three map projection families PlanarCylindricalConical Tangent - Case Projection surface may either touch the globe at a point (point of tangency) or along a line (line of tangency) Secant - Case planar projection surface intersects the globe along a small - circle line of tangency Azimuthal Projections (planar projections)projecting onto a plane tangent to the globe at a point Azimuthal projections that preserve global directions Conformal angles on the globe are preserved on the map"correct form or shape" Equidistance preservation of distance on a map projection Aspect Location of the point or line(s) of tangency on the generating globe What are the 4 map projection properties? AzimuthalConformalEquidistanceEqual Area Four map projections on geometric distortions mercator cylindrical conformaltransverse mercator lambert conformalalberts equal area Orthographic projection is how the earth would appear if view from a distant planetall rays of light are infinite and parallel Stereographic projecting a light source from the antipodal point on the generating globe to the point of tangency Gnomonic earliest map projections, first used for star maps by Greek scholar Thales of Miletus in 6th century B.C.all great circles on the earth are shown as straight lines Azimuthal equidistant projection in its polar aspect has the distinctive appearance of a dart board - equally spaced parallels and straight- line meridians radiating outward from the poleall straight lines drawn from point of tangency are great circle routes Rhumb Lines all lines of constant compass direction; are straight lines on mercator map Peters Projection world map showed 3rd world countries more fairly Transverse Mercator Rhumb lines are not straight lines; north - south of earth are projected with no local shape distortion and little distortion in area Universal Transverse Mercator (UTM) 84 degrees N to 0 degrees to 80 degrees S latitude Cartesian Coordinates square grid on the map with divisions left to right on horizontal X axis and divisions bottom to top labeled on a vertical Y axis State Plane Coordinates created in 1930's by land surveying in US define property boundries Metes and Bounds System Property BoundryLegal property description tied to earth features and remained useful as long as neighbors agreed with place names and accepted the boundries French Long Lots Along rivers or lakes = chief source of transportation and communication for Frenchwaterfront as parallels lines, creating narrow ribbon farms or long lots US Public Land Survey (USPLSS) Township and Range SystemPrior to settlement and required all grants be recorded1-36 37< = Donation Land ClaimsPrinicpal Meridians and Base Lines External Errors impose methods on the map from the outside judgements, calcualtions, methods Internal Errors distortions in a map Physical measurement for distance use scale baruse latitude as a scale baruse map rulersuse mechanical measuring devices Orienting by Inspection 1 liner feature2 liner featuresProminent objects Magnetic Declination angular difference between true and magnetic Agonic Line true and magnetic north poles are aligned Compass Points early mariners, use winds to find their way Wide Area Augmentation System (WAAS) GPS correction data for precision aircraft positioning GPS Global Positioning System AuthorKinazulu808 ID46418 Card SetGeo 301 Midterm DescriptionGEO 301 Midterm Updated2010-11-01T06:20:40Z Show Answers