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125 Cards in this Set
- Front
- Back
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Meridian/ Line of Longitude
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each half of a great circle that joins the poles(specify locations in the east-west directions)
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Prime Meridian
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Starting Point. current maps use Greenwich, England as prime. (value of 0). 180th meridian is the highest number meridian(opposite side of the world)
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Parallels
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locational lines placed at right angles to the meridians.
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Equator
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Great Circle midway between the poles.
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Small Circles / Lines of Latitude/ Parallels
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Created when a plane passing through the earth divides the earth into two unequal portions. (parallel to the equator)
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Graticule
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Pattern of meridians and parallels on the earth....
Assume earth is a sphere: 1. Parallels are equally spaced between the equator and the poles. 2. Parallels are always parallel to one another, so any two parallels are always the same distance apart all the way around the globe. 3. Meridians are spaced farthest apart on the equator and converge to a single point at the poles. 4. Parallels and meridians cross one another at right angles. |
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Ellipsoid
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bulge slightly in the middle, flatten slightly at the poles.
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Geoid
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"irregular" ellipsoid. Lumpy surface that effects geodetic surveys that provide framework for maps.
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Eratosthenes
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250 B.C. measured the earth using geometry and simple observations. Summer Solstice(noon sun is directly overhead on the Tropic of Cancer). Used the angles to determine circumference.
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Chronometer
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extremely accurate clock developed by Harrison (1773).
used by ships, maintained time despite environmental problems at sea(heat). Relationship between time and longitude(every hour, sun passes over 15 degrees of longitude) |
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Horizontal Datum / Vertical Datum
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starting elevation to which elevations on a map are referred.
Common starting point(sea level). |
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Plane Surveying
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the earth's curvature does not affect the accuracy of the map. (sewer systems, county highways)
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Stereoscope
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allows one eye to see one view and the other eye to see the other. Parallax is obtained...stereoscopic image.
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Parallax
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one eye sees a scene from a slightly different angle than the other eye(causing 3D).
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Map Projection
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a systematic rendering of a graticule of lines of latitude and longitude on a flat surface.
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Three Physical surfaces common for construction of map projections.
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plane
developable surfaces -- cylinder and cone. |
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Plane
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simplest projection surface. (azimuthal projections)
does not have to undergo further distortion/ manipulation because it is a flat map. tangent at the pole (polar azimuthal) |
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Gnomonic Position
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center of the globe.
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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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Orthographic Position
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infinity.
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Cylinder
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normally oriented so that it is tangent along the equator.
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Cone
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normally oriented so that it is tangent along a parallel (aligned with the axis of rotation)
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Transverse Projection
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Projection surface is turned 90 degrees from normal.
Cylinder- tangent along a meridian. Plane- tangent along equator. Conic- apex of the cone on the plane of the equator. |
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Oblique Projection
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Projection surface lies at an angle somewhere between the normal and transverse positions.
Between 0 and 90 degrees. |
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Standard Line
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line of tangency between a projection surface and the surface of the globe.
along the standard line the map has no distortion( one-to-one relationship between projection and globe). |
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Secant Projection
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Projection surface intersects the globe.
Cone/ Cylinder: 2 standard lines. Plane: Distortion everywhere except point of tangency. |
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Conformality
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retention of correct angles on a map.
Map features can be recognized by their distinctive shapes. REQUIREMENTS: line of latitude and longitude cross one another at right angles and that the scale is the same in all directions at any given point. (only achieved for small areas on map). |
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Equivalence
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a unit area drawn anywhere on the map always represents the same number of square units on the globe's surface.
Equal- Area(equivalent) Projections. Retaining equivalence distorts shapes. (used to represent the areal extent of various phenomena on the earth's surface). |
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Distance
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length of a straight line between two points on a map represents the correct Great-Circle distance between the same points on the earth.
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Direction
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straight line drawn between two points on the map shows the Great-Circle route and azimuth between the points.
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Azimuth
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The angle formed at the starting point of a straight line in relation to the baseline (meridian).
-measured clockwise from north. |
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Conformality vs. Equivalence
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no map can be both conformal and equivalent.
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Mercator
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retains conformality. (conformal projection). (right angle graticules)
useful for navigational purposes. |
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Sinusoidal
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equivalent projection.
scale is true along the central meridian and each parallel. |
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Azimuthal Equidistant
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preserves the globe quality of equidistance.
Area and shape relationships are not retained anywhere on this projection and are increasingly distorted away from the center. |
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Gnomonic
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all straight lines represent portions of great circles.
(light at center of earth)--spacing of the graticule increases rapidly away from the center of the projection resulting an an increasingly exaggerated scale. |
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Compromise Projections
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Miller Cylindrical - shows the world in a rectangular format.
atlases, classroom use. Robinson - designed by Arthur Robinson, minimizes visually disturbing distortions that make many projections unattractive for general use. Winkel Tripel - National Geographic, balance between size and shape. |
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Interpolation
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calculating location when it is not on a specific line of longitude/ latitude.
-- lies between the graticule lines.(used to estimate the intermediate coordinate value) |
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GEOREF
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World Geographic Reference System.
convenient and rapid reporting and plotting of locations. Military operations, latitude/ longitude are divided by a simple set of letters and numbers. 1st zone to the east of 180 degrees is identified by A. |
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MK LK 385250
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GEOREF
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67°14' 12.4" N 23° 12' E
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Geographic Coordinate
(Cartesian Coordinate System) |
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Universal Transverse Mercator (UTM) system
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two standard lines.
covers the earth's surface between 80° South and 84° North. (covers polar caps) 60 north-south zones (6° of longitude wide) civilian and military systems |
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Civilian System
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false origin at 500000 m west of central meridian.
locational grid system is imposed on the two (UPS) projections. eastings and northings. uses only numbers. |
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Military Grid Reference System
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84° North and 80° East (divided into grid zones that are 6° east-west by 8° north-south).
identified by a column number and a row letter. |
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18TWC873130
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Military Grid
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4123514 mN; 123651mE; Zone 22, S
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UTM
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2176999 ft E 210313 m N; CA Zone 5
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SPCS
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State Plane Coordinate System (SPC)
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rectangular coordinate system that is individually applied to each of the US.
Lambert conformal projection - used for east-west trending states. Transverse Mercator - used for north-south trending states. |
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Bearings
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angular difference between a north or south reference and the surveyed line.
north 45° east |
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United States Public Land Survey (USPLS)
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started in Ohio.
rectangular survey system when the settlement of the western portion of the nation was in its early stages. |
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Townships
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1. east-west lines in the grid form rows (in the grid formed by the baseline and meridian)
2. Intersection of the township rows and range columns creates a pattern of squares (townships). |
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Baselines
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USPLS( initial point is 1st established for the region to be surveyed)
east-west baseline is set at a right angle to the north-south principal meridian |
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Lots
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used when the normal system of fractional sections cannot be applied.
- kept as close to 40 acres as possible. |
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Standard Parallels
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established every 24 miles north or south of a baseline.
north-south guide meridians are surveyed, at a standard spacing of 24 miles. |
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Scale
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the ratio between map distances and earth distance.
1. word statement 1 inch to 1 mile 2. Arithmetic ratio Representative Fraction (RF) 1 : 100000 "unit-free" 3. Graphic Symbol scale on the map (directly translated to correct earth distance) |
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Knot
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one nautical mile per hour
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Fathom
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6 feet, defined by the amount of sounding line that could be encompassed between the outstretched hands of an average seafarer.
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Measurements from Maps
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1. distances between locations.
2. Areas of regions. |
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Opisometer
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map measure, tracing wheel that can calculate real world distances by tracing distance on a map.
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Paper- Strip Method
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using tick marks and the scale of the map, dividing distances into legs.
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Error Sources for Map Accuracy
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1. Measurement Error
2. level of generalization of the line being measured 3. Vertical Displacements along the route. |
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Smoothing
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Simplification.
the smaller the map scale, the greater amount of simplification that occurs. Simplification of a line results in shortening the distance between the start and end points. |
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Slope Errors
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features are shown orthographically on a map.
their distances apart are not affected by elevation differences as they would on the earth (flat earth). |
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Polar Planimeter
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an instrument that measures areas on a map in terms of square inches or square centimeters. measurements are then arithmetically converted to earth measurements.
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Gyrocompass
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determines true north.
(used night or day) aligns itself with the spin of the earth's axis, its north arrow points true north and is not affected by the vagaries of earth's magnetic field. |
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Magnetic Declination
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difference between true north and magnetic north.
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Isogonic Chart
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special map shows the magnetic declination
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Agonic Line
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the isogonic line that joins points of zero declination.
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Compass deviation
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difference between the direction to the north magnetic pole and the direction the compass needle actually points.
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Orthodrome
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(true azimuth) refers to the direction of a great circle
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Resection
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2 to 3 known positions on the ground are located and marked on the map. the magnetic azimuth to one of the known positions is determined by taking a compass sighting.
ideally the lines will intersect at the same location. Triangle of Error is formed if they do not. |
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Nautical Chart Types
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Harbor Charts
Coast Charts General Charts Sailing Charts |
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Notice to Mariners (NTM)
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published weekly by the Marine Navigation Department of NIMA.
notices specify changes to aids to navigation and other information of importance for waters used by large oceangoing vesses. |
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Rhumb Line/ Loxelodrome
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Mercator Projection (straight line drawn between two points represents a line of constant heading).
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Nautical Charts Symbolization
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upright lettering for features that are at higher water.
Italics for submerged or floating features. |
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Nautical Position
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Bearing is the nautical term for an azimuth. (angle between a reference direction and the direction to an observed feature)
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Radar
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active remote-sensing technique involving the transmission, reflection, and detection of radio waves that are only a few centimeters in length.
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Global Positioning Systems (GPS)
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accurate, virtually automatic position determination.
24 hour basis, all types of weather. basis of GPS is a constellation of 24 satellites operated by the Defense Department. |
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Loran
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employs pairs of radio-transmitting stations called master(M) and slave(S) stations located some distance apart.
affected by weather. |
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Sectional Charts
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based on the Lambert conformal conic projection.
published at 1:500000. topographic data, radio aids to navigation and comm., airport traffic and airspace/airport information. designed for visual navigation of slow-to-medium-speed aircraft. |
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World Aeronautical Chart (WAC) series
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Lambert conformal conic projection. 1: 1000000
shows cities and towns, principal roads, railroads and distinctive landmarks. moderate-speed aircraft. |
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Aneroid Altimeters
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as altitude increases, barometric pressure decreases, and these alimeters convert the current pressure into a direct altitude reading(for planes)
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Visual Flight Rules
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governs flight in favorable weather conditions, in which visual references to landmarks can be used to reliably control the operation of the plane.
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Instrument Flight Rules
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When some or all of a flight occurs under conditions that are not favorable(prevent visual contact), instruments must be used to determine location, direction and altitude.
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Absolute altitude / Radio Altimeter
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altitude above the earth's surface instead of above sea level.
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Spot Heights
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indicates the elevation of the earth's surface at that point relative to some datum.
typical at: crest of hills, road intersections, railroad grade crossings. (easily identifiable points). |
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Bench Mark
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placed by geodetic surveyors.
An ideal location for a spot height because it can be precisely located in the field and then used as a reference point for additional survey work. |
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Contour
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Imaginary line that joins points of equal elevation above or below some datum.
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Contour Interval
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vertical distance between contours. (selected by mapmaker)
wider interval is used for small-scale, generalized maps, to avoid overcrowding. |
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Isobaths / Depth Curves
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contours drawn to represent the bottom configuration of a water body.
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Intermediate Contours
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regular contours, spaced at the normal interval and drawn with a fine line weight, lie between the index contours.
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Index Contour
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numbers associated to indicate the elevations that they represent.
bold line is used |
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Supplementary Contours
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additional contours used to supply additional details.
usually used in areas of flat terrain. |
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Depression Contours
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indentations in the earth.
represented by tick marks inwards. |
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Approximate Contours
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Contour lines drawn to represent the likely surface of the terrain.
represented by dashes/dots. |
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Carrying Contour
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single contour drawn to represent the several contours that would be drawn if space allowed.
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Underwater Contours
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contours that represent the land surface that was exposed before any type of flooding.
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Block Diagrams
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primary purpose: illustrate the relationship between the features and not to provide measurements, which are obtained from traditional maps.
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V-shaped cross section
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water cut steam valleys (contours make a V on maps)
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U-shaped cross section
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glacial valleys (contours make a U on maps)
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Flood Zone Map
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topographic map used to show the terrain surface in areas likely to flood.
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100-year Flood
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Major level of flooding that has one chance in one hundred of being equaled or exceeded in any one-year period
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Profile
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cross-sectional view through a particular piece of terrain.
provides info. about the relative steepness of terrain. |
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Cut-line
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when drawing a profile, begin with the selection of starting and ending points that fit the needs of the task at hand.
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Vertical Exaggeration
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use of a vertical scale that is greater than the horizontal scale.
-visually more satisfactory appearance to the features shown. |
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distance around the earth
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40000000 meters
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Large Scale
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global, extensive
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Small Scale
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detailed, localized.
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Gradient
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defines the maximum slope of a surface.
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Slope-Zone Map
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shows by means of coloring/shading areas of relatively homogeneous slopes.
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Maximum slope
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Gradient. (if the objective is to be reached, the route must not include grades that are steeper than the operational limit).
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Concave Contours
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If contours are closely spaced at the top of a slope and widely spaced at the bottom.
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Convex Contours
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If contours are widely spaced at the top of a slope and closely spaced at the bottom.
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Trafficabiltity
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the ability of an area to support vehicles of a certain type.
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Intelligent Vehicle Highway Systems (IVHS)
Automated vehicle location(AVL) |
benefits from this integration include informing drivers and onboard computers of traffic conditions.
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Pathfinding
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As the vehicle moves, the system monitors its direction and distance of travel.
(dead-reckoning process) |
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Trip Planning Programs
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allow for:
specify an origin and a destination. specify preferences, such as selection of the shortest route, more scenic, or avoidance of certain roads. |
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Circumference of the Earth
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40000000 meters
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Difference between polar earth diameter and equatorial diameter
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42000 meters
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International Meridian Conference
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1884
-established the use of a single prime meridian. -established the Greenwich meridian as Prime meridian. -established universal day -held in Washington, D.C. -26 Countries agreed. |
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Ptolemy
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inventor of first 3 map projections to be scientifically described.
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Observation of Latitude:
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sun, star Polaris, Satellites, maps.
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Analemma
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graphic device used to show the equation of time and declination of the sun at different days of the year.
Figure 8 shaped diagram that gives information about the latitudes at which the sun is directly overhead throughout the year and about the equation of time. |
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Space- Oblique projection
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used for satellite imagery.
invented in 1970's by John Synder. |
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Saddle Point
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one direction is a peak
another direction is a valley (midpoint between peaks) |
