definitions

Definitions:

  • Point-to-Point Correspondence: idea that each pt. on earth is transformed to a corresponding pt. on the map projection 

  • Continuity: preservation of spatial proximity at all locations

  • Graticule :  model of earth-centered coordinate system, most commonly latitude and longitude

  • Pattern of Distortion : illustrated through a diagram known as Tissot’s indicatrix

  • Sinusoidal : Equal-area

  • Robinson : based on table of coordinates, not mathematical formulas

  • Equidistant Conic: Used to portray area near, not overlapping, the Equator

  • Albers Equal Area Conic : Distorts scale & distance

  • Lambert Conformal Conic : True directions in limited areas

  • Conic projections: Equidistant, albers equal area, lambert conformal

  • Cylindrical projection: EQUIRECTANGULAR, MERCATOR,Gall’s Stereographic Cylindrical, Peters Projection, TRANSVERSE MERCATOR

  • TRANSVERSE MERCATOR : used to portray areas with larger N-S than E-W extent

  • Peters Projection : special case of Gall’s equal-area

  • Gall’s Stereographic Cylindrical : secant

  • MERCATOR : used for navigational maps & charts

  • EQUIRECTANGULAR : also called equidistant cylindrical projection

  • Plane(azmithual) : commonly used for mapping polar regions; good for areas with about = N-S & E-W extents 

  • CONIC: great for representing mid-latitude regions in either hemisphere 

  • CYLINDRICAL: good for maps of entire Earth

  • Plane: Orthographic, Stereographic, Gnomonic, Azimuthal Equidistant, Lambert Azimuthal Equal Area

  • Stereographic : good for navigating polar regions

  • Developable surface :  flat surface that Earth’s features are projected onto

  • Equivalent projections: preserves relative size of regions on the map

  • Conformal projections: preserves angles on globe on the map, ultimately preserving shape 

  • Equidistant projections : preserve distance relations

  • Datums : collection of very accurate control points

  • Geodesy: science of measuring and modeling the earth in 3D

  • Ellipsoid : mathematical model of Earth with major and minor axes 

  • Flattening ratio : rate ellipsoid flattens as one approaches poles   

  • horizontal datum : ellipsoid + flattening ratio & basis for fitting ellipsoid model to Earth’s surface

  • vertical datum : basis of measuring elevation & 0-reference for elevation.

  • the mean sea level (MSL) : avg. of all low and high tides at particular starting location over a metonic cycle

  • Spatial : location

  • Representation : something that stands for or portrays something else; likeness; simplified model 

  • Graphically : drawn or capable of being drawn, with a “unique” arrangement of features; encompasses diversity

  • Communicate :  the map’s ultimate purpose is to convey information to the reader 

  • Topographic : reference maps

  • Thematic : themed map

  • Spatialization : Origins of language & growth of spatial consciousness in humans are closely interrelated

  • Primary source : gathered first hand, collected in the environment 

  • Secondary source : derived from primary data such as focus groups or surveys

  • tertiary source : deprived from secondary data such as websites or reports

  • Types of thematic maps : themed, # of people in a county, doted like population maps

  • Types of topographic maps : traditional reference map or atlas, globe

  • Absolute relief mapping : shows precise elevation info

  • Relative relief methods : Shows various landforms & general impression of relative height

  • Contours : lines of equal elevation above a datum

  • Parcels/tracts : areas that imply landownership or land use

  • Lot :  special type of parcel within subdivision, recorded on map

  • Plat : map drawn to scale that shows the lots

  • Platted Subdivision : mapped subdivision showing subdivided lots 

  • Cadastral system :  the means by which property ownership is recorded, boundary lines drawn, and land parcels delineated