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Standard parallel
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In the US Public Land Survey, east-west reference line established at 24-mile spacing. In normally oriented conic or cylindrical map projections, parallel of intersection of the project surface with the globe.
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Mercator
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Conformal map projection that shows the world (less the polar regions) in a rectangular format. Useful for navigational purposes because all the straight lines drawn on it are lines of constant compass direction.(Scale distances become increasingly exaggerated away from the equator and toward the poles.)
Shapes of smaller, individual features are correct but not over large areas suh as continents. Used for navigational charts.
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plane
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Flat surface used for azimuthal projections.
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Satellite images
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can be taken fomr a spacecraft with or without a crew.
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Monument
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Plaque placed at a survey control point to designate location and/or elevation.
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Coordinated Universal Time (UTC)
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The basis of times observed in each time zone. Formerly known as Greenwich Mean Time (GMT).
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foot
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Unit of measuremnt in the US Customary system, defined as 1:0.30480061 meter. Since 1959, also know as the US Survey foot.
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World Geographic Reference System (GEOREF)
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Allows more convenient and rapid reporting and plotting of locations.
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Seigneury
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Seventeenth cerntury French land grant in the region that is now Quebec and the Maritime provinces except Newfoundland. Granted for the purposes of promoting settlement and development.The land holders were called seigneurs.
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Mile
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Unit of measurement in the US Customary system. Defined as 5280 feet (1069.35 meters)
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Scale
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The ration between map distances and earth distances. Can be expressed as a 1) Word Statement; 2) Arithmetic ratio (representative fraction), or 3) a graphic symbol.
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grid
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graticule
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Parallax
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Difference in viewpoint of one eye versus the other, which results in a three-dimensional, stereoscopic image.
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What is a map?
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A bird's eye view of all the earth's surfaces and or a concrete or abstract representation of the features that occur on or near the surface of the earth or other celestial bodies.
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Apparent Solar Day
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The period between one noon and the next at the same location.
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Highest numbered meridian
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180th, opposite the prime meridian
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Methods of specifying locational information
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1) Latitude and Longitude Coordinate System
2) State Plane Coordinate (SPC) system
3) World Geographic Reference System (GEOREF)
4) Universal Transverse Mercator (UTM)
5) Universal Polar Stereographic (UPS) systems
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North American Datum of 1927
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Historical basis of maps of North America, based on a vast control network originating at Meade's Ranch Kansas.
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Graticle
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The pattern of the meridians and parallels on the earth.
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Word Statement
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Statement of scale ratio in words.
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mean datum
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Vertical datum that averages long-term tidal variations. Max. accuracy is hour computations for 18.6 years.
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Inset
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Additional small map with larger map. It can be 1) An enlarged portion 2) Locator map, 3) Areas related to main map, 4) Additional information.
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Lot
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In US Public Land Survey, subdivisions used when the normal system of fractional sections cannot be applied, such as along the northern and western edges of some townships or along the shores of navigable streams or lakes 25 acres or more in extent.
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Geodetic Control Networks
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From two starting locations determined by astronomical observations, using a system of triangulation, the surveyor is able to calculate the locations of newly observed points.
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Computer-assisted Cartography is:
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Applying computers to the processing and analysis of remote-sensing data and operation of geo-graphic information systems and then to the production of maps.
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Thematic Maps
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Show information about any of a myriad of special topics superimposed on a base map.
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Transverse projection
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Turned 90* from normal. Tranverse Cylinder is tangent along a median. Transverse plane is tangent along the equator.
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Equator
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A great circle, placed at right angles to the meridians, and located midway between the poles.
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Bathymetric maps
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Water depths and the configuration of underwater topography.
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Orientation
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The way a map is aligned relative to the earth's surface. See North arrow.
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Ephemeris
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A set of tables that more exactly (then an analemma), provied information about the latitudes at which the sun is directly overhead throughout the year.
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Gnomonic projection
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Map projection on a plane, with the light source at the center of the earth. All straight lines drawn on a gnomonic projection represent portions of great circles. Used for navigational charts.
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What is the scale?
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The ratio between the size of features on the map and the size of the same features on the ground. It can be a representative fraction, a word statement or a graphic scale.
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Secant projection
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Projection in which the projection surface intersects the globe. (Cone or cylinder would have two standard lines. A tangent plane woud have one.)
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Direction
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The path along which something is moving or pointing.
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Planimetric base map
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Used to provide framework for thematic maps.
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Transverse Conic
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Apex of the cone on a plane of the equator.
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Chronometer
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Extremely accurate clock
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Sinusoidal projection
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An equal area (equivalent) projection.Looks like a flattened tear drop with points. i.e. Albers equal-area (often for U.S. maps); homolographic; The Goode interrupted homolosine; the Bonne
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Major Properties
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Can exist at all points on certain projectes - Conformality & Equivalence
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Standard North American datum
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Used in the U.S. and North America - adjusted in 1929 and in 1988. (NAD 1988)
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Grid ticks
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Short lines to indicate the intersection of the graticule with the map outline (Called a neatline.)
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Prime meridian
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The starting point - most maps use Greenwich England which then gets a value of 0.
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Cartesian Coordinate System
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Four-quadrant system of locational coordinates
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State Plane Coordinate (SPC) System
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Rectangular coordinate system individuallyapplied to each of the United States. Each state is split into zones. With exceptions, the Lambert conformal projection is used for east/west trending states and the transverse Mercator is used for north/south trending states.
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Great-circle distance
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Shortest distance between two points on the earth's surface, represented by the path of a great circle.
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Legal Subdivision
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In the Canadian Land Survey System, division of a section into sixteen 40-acre subdivisions, which are equivalent of quarter-quarter sections in the US Public Land Survey.
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Military Grid Reference System
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Military version of UTM/UPS Systems - Avoids long strings of numerals. 84* North to 80* South, divided into grid zones 6* east/west by 8* north/south. Each grid has column number and row letter. Column numbers are 1 - 60. Row letters are C - X omitting I and O. i.e. 3N AND, Polar Grid Zones are A/B for south and Y/Z to north.
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Canada Land Survey System (CLSS)
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Survey system established in 1870 to provide an orderly land-ownership framework in the prairies and mountains of western Canada. uses principal meridians and baselines, townships, ranges, sections, and subdivisions of sections.
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Differential leveling
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Put a level between two points. Measure a rod above the known point, turn and meause a rod above the new point, the difference is it's elevation difference with the known point.
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Bearing
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The angular difference between a north or south reference and the direction of the surveyed line. (i.e. north 45* east)
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Principal meridian
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North-south reference line used in a US Public Land Survey Zone.
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Line route maps
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Specialized maps used by utility companies to show routes and right of ways of their transmission lines or pipelines. (Cadastral map)
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Orthographic position
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The light source at infinity
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Standard line
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The line of tangency between a projection surface and the surface of the globe. Alnong the standard line, the map has no distortion. (If along a parallel, can be called the standard parallel.
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Geoid
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An ellipsoid with a slightly irrregular shape caused by variations in the density of various portions of the earth's crust.
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Unsystematic subdivision
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Land-ownership pattern developed in an unplanned manner, using, for example, property boundaries established on the basis of settler's claims. (Mostly colonial U.S.)
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Plane Rectangular Grid (reference grid)
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System of lines superimposed on a map for locational purposes that does not take the curvature of the earth's surface into account.
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Horizontal datum
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Starting elevation to which elevations on a map are referred. Necessitated by today's engineering and scientific accuracy requirements and made possible by satellite observation methods.
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Magnetic Declination
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The difference between the direction to the north magnetic pole and the direction to the geographic pole.
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Orientation of a projection surface
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May be changed as desired but certain orientations are normal.
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Rotures
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Lot allocated to an individual farmer in the seigneurial land ownership system of French Canada.
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Supplemental inset
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Can be treated as individual map with it's own legend, scale, direction and other features.
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Universal Transverse Mercator (UTM) System
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Plane rectangular grid system that covers the earth's surface between 80* South and 84* North. Used in conjunction with the Universal Polar Stereographic (UPS) System, which covers the polar caps. Civilian system that uses only numbers, while the US Military Grid Reference System uses number/letter combinations to designate grid zones. 60 north/south zones, each 6 degrees wide. Each zone overlaps the other zone by 1/2 degree.
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Small circles
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Parallel to the equator but the lines of latitude created by planes passing through the earth both north and south of the equator.
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Stereoscope
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Simple instrument that permits the simultaneous viewing of a stereo pair of aerial photographs so that the desired three-dimensional effect is achieved.
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Isoline maps
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Show numerical values for continuous distributions by means of lines joining points of equal values.
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gores
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Tapered strip map used in globe construction.
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Flood-prone area maps
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Provide information about areas subject to flooding. Derived from topographic maps.
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Planimetric map
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Maps that do not show relief features in measurable form. Usually the simplest form of map.
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Stilling basin
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Used to get mean sea level. Cut off from the direct influence of wind and waves.
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Oblique aerial photograph
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Taken with the lens pointed at an angle away from the vertical.
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Ellipsoid
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Earth's shape due to it's revolving easterly and that generating centrifugal force whih causes the earth to bulge at the middle and flattern at the poles.
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Poles of rotation
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Proving for a starting point of a locational system
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Township plats
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Detailed map of the land-ownership boundaries within a US Public Land Survey township.
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What is a title
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Map Subject, Time period of map, other content aspects
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Earth
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A sphere, by convincing and direct evidence such as astronauts.
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Cartograms
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Cartograms are a deliberately distorted unique representation that substitute a different standard of measurement (time or cost) for the distance or area measurements customarily used.
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stereomodel
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Apparent three-dimensional view of the terrain, as viewed in a stereoplotter.
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Oblique azimuthal (plane)projection
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Plane leaning along side of earth, not a polar tangent of an equatorial tangent.
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Eratosthenes
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A Greek mathematician who first measured the earth in 250 B.C.
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Metest and Bounds surveying
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Method of land survey used to describe unsystematic land ownerships. Records the direction and length of each portion of the boundary line of the property in sequence, often using distinctive markers, such as trees of particular species.
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Thematic Flow maps
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show direction and amount of movement, as well as the types of goods or services moved.
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Vetical Aerial Photographs
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Used for mapping purposes and taken with an aerial survey camera. Typically 9 inches (23 cm) square.
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map projection
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Systematic rendering on a flat sheet of paper of the earth's graticule (lines of latitude and longitude).
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Astronomic latitude
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measuring the angle between Polaris and the observer's horizon.
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North America Datum of 1983
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Now, standard reference for maps of continent. Recalculation of NAD of 1927.
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Polaris
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The north star, which, when standing at the north pole, appears to be directly overhead. (Actually 1.5 degrees away.)
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Ground control points
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An easily identifiable point on the ground established to tie remote-sensing images to a ground survey.
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Guide meridians
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In the US Public Land Survey, north-south reference line established at 24-mile spacing.
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Control diagram
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Map based on a survey used to establish ground locations of control points for aerial photography.
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Globe
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spherical model of the earth
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Retaining correct shapes
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Conformality
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US Customary Units
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Units of measurement, such as feet, inches, and miles, based on the units of the older English system.
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Time zones
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24 zones on earth, each 15 degrees. Earth rotates through one each hour. Central meridian of each zone is the time meridian.
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What is in a legend?
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map symbols and their explanation
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Aiquot parts
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Division of a US Public Land Survey section into various combinations of quarters (160 acres), quarter-quarters (40 acres) and halves (80 acres).
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Dot-distribution maps
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A thematic map in which dots are used to represent a specific quantity of a particular variable.
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Locator map
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One that shows where the map is found in a larger, better know region. (Can be an inset map.)
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Trilateration networks (Historically more common Triangulation Networks)
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Basing surveys on the measurement of distances, just as in Triangulation, they were based on the measurement of angles.
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stereographic position
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At the antipode (The point exactly opposite the point of tangency of the projection surface.)
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Meander line
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In the US Public Land Survey, line surveyed along the mean high-water elevation of a navigable water body. (High water lines are used to establish property boundaries.)
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Parallels and Meridians
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Cross each other at right (90*) angles.
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Azimuthal equidistant projection
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Map projection on a plane, in which all points are plotted at their true distance from the center of the projection and are in their true global direction (azimuth) from the center. Both poles bent to touch tangent. Preserves the globe quality of equidistance.
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Retaining Equal-Area characteristics
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Equivalence
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Vertical aerial photograph
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Taken with the lens pointed straight down at the ground.
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True azimuth
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Direction of a great circle. Also known as an orthodrome.
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Equation of Time
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The difference between the mean solar time and the apparent solar time.
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Equivalent (equal area) projection
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Projection on which equal areas are retained, so that a unit area drawn anywhere on a map always represents the same area on the earth's surface.
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Orthographic view
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View drawn as though every point were seen from directly overhead, such as a map.
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Lambert Conformal conic projection
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Used for mid-latitude air charts because straight lines drawn on it very closely approximate great-circle routes.
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Hypsometric tints
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Layered tints showing relief
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Deflection of the vertical
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The difference at a given location between a vertical line drawn to the center of the earth and a verticl line drawn to the earth's center of gravity.
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What is cartography?
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The art, science and technology of making maps, together with their study as scientific documents and works of art.
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International Date Line
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The 180th meridian, a 1/2 day away from the Prime Meridian.
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Ranges
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The north-south lines in the grid form columns.
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Stereoscopic image
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Three-dimensional image (especially of aerial photographs) showing the same scene from slightly different points of view. Used for stereoscopic (three-dimensional) viewing.
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Baseline
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Line that serves as the basis for a survey, with endpoints, direction, and lengths that are accurately known. Or east-west reference line used in conjunction with a U.S. Public Land Survey principal meridian.
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Floating mark
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In stereoplotter, point of light that appears to be suspended over the stereomodel. Used to transfer locational information
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Oblique projection
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Results if the projection surface lies at an angle somewhere between normal and the transverse positions.
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Outline map
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Outlines that provide a framework for plotting information - like empty U.S. map with just rivers and lakes.
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Mean Solar Time
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Depending on the time of year, each solar day differs from one part of the year to another, therefore the mean solar time is 24 hours because it uses the average length of a day throughout the year.
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Geodetic Control Surveys
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the curvature of the earth and determine locations in terms of latitude and longitude.
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What is part of almost all maps?
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Typographical information including titles, legends, names and notes.
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Cadastral map
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Usually includes the location of property-ownership lines, with their bearings and lengths, the ownership and size of land parcles and similar information - think platt maps.
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perspective view
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view of a scene from a single viewpoint, such as an aerial photograph.
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Cadastral surveys
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Survey used to determine land-ownership boundaries and property descriptions. In the United States, preferably reserved for land-ownership surveys of the public lands.
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Aerial photographs
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The most common remote sensing product.
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Developable surface
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Projection surface, especially a cone or a cylinder, that is not flat at the time the projection is created but that can be flattened later.
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Choropleth map
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A thematic map that shows distributions summarized on the basis of areas delimited by state or county boundaries or other arbitrary boundary lines. (Each ara is colored, shaded, dotted, or hatched to appear as a darker or lighter tone.)
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Minor properties
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Those that can exist in relation to only one or sometimes two points or lines on certain projections. Distance and direction
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Great Circle
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The line defined by the intersection of a plane passing through the center of the earth and it's intersection with the earth's surface.
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gnomonic position
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light source at the center of the globe
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Spacing dividers
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Eleven-point dividers used for measuring interpolated locations.
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Rectangular Survey System
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Method of land survey, utilizing townships and ranges. Started in Ohio and ultimately extended throughout most of the western states and parts of the south. Originally known as the rectangular survey system. Now knows as the Public Land Survey, U.S. (USPLS, systematic subdivision)
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Plane survey
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A survey in which measurements and computations are made without considering the earth's spherical shape.
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Normal projection
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Cylinder would be tangent at the equator. Cone would be tangent along a parallel with the apex above the pole. The normal orientation of a plane is tangent at the pole (Polar Azimuthal.)
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Townships
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Six-mile-wide, east-west zone in the US Public Land Survey and Canada Land Survey System. Also, 36-square mile area formed by the interesection of an east-west township and a north-range.
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What is a neatline?
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A narrow line that frames the map area.
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Equidistant maps
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Map with the characteristic of correct distance relationships.
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Radar image
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A remotely sensed product where a special transmission is beamed from a power source and reflected energy is captured and converted into an image of the scene.
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Stereo pairs
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Overlapping photos which provide two slightly differing views of each portion of the earth's surface.
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Interruption
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Involves separating the projection along several dividing lines. such as equal-area projections.
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Compromise projection
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Map projection that does not preserve any of the globe properties but also does not result in extreme distortion of any property.
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What is a mental map?
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Images we have in our minds.
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Lines of longitude or meridian
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Each half of a great circle that joins the poles.
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metric system
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System of measurement originally defined by the French Academy of Sciences in 1791.
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Landscape Map
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provides detailed site information and planting plans for gardens and parks.
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Declination of the sun
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What latitude the sun is over through the year - and is used to adjust the calculation when an observation of the sun is being used to determine the latitude of a point on the earth's surface.
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Analemma
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A figure eight-shaped diagram which gives information about the latitudes at which the sun is directly overhead throughout the year. A visual picture of the equation of time. An analemma is usedto determine the equation of time on any given date.
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meter
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Basic unit of measurement of the metric system. Originally defined bas one ten-millionth of the great circle from the earth's equator ot the earth's pole. Since 1983, defined as the distance that light travels in 1/299,792,458 of a second.
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Plane of the eliptic
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The imaginary plane that passes through the sun and the earth at all positions of the earth's orbit around the sun. Earth's axis tilts 23.5 degrees relative to a line perpedicular to the Plane of the eliptic.
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Representative-Fraction (RF) scale
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The ratio between the map distance and the ground distance between equivalent points.
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Remote sensing
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gathering information by means of a sensor that is not in contact with the objects in the scene being observed.
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Compromise Projections
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1) The Miller Cyllindrical - Shows the world in a rectangular world. Modified from the Mercator so that it distorts the size of areas less.
2) The Robinson -Minimizes visually disturbing distortions. (Rounded belly)
3) The Winkel Tripel - Used by National Geographic. Based on the balance it provides between size and shape.
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What is an engineering map?
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Detailed Maps, sometimes called plans, used in engineering projects and to aid in estimating construction costs.
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Land-partitioning systems
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1) Metes and Bounds : Unsystematic
2) U.S. Public Land Survey (Canada Land Survey System - CLSS) USPLS
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Parallel
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Lines of latitude, placed parallel to the equator
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Metonic cycle
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The complete cycle of relationships between the sun, moon, and earth evolves over 18.6 years.
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General rule for plane coordinate systems
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Locations are defined by giving the east-west coordinate first and the north-south coordinate second.
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Summer Solstice
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Whent the noon sun is directly overhead.
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Conformality
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The retention of correct angles on a map.(Can only occur in small areas.)
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Datum
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Fixed elevation, such as mean sea level, used as a starting point for a vertical survey.
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international foot
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Defined as 1:0.3048 meter. Compare with US Survey foot. (See foot)
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Polar Flattening
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Earth's radius is slightly greater at right angles to the axis of rotation and slightly smaller along the the axis For earth, it's 1/298 or almost 0.
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Interpolation
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Method of logically determining the elevationof a point that is not on a contour or a spot height. Althernatively, method of determining the coordinates of a point not located on a grid or graticule line.
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Sections
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Townships formed by township rows and range columns are subdivided into thirty-six sections, each about 1 square mile (640 acres), their exact size of actually surveyed townships often differs from the standard.
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Topgraphic map
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Shows the shape and elevation of terrain. (Greek topos = place & graphien = to describe)
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