Perry-Castañeda Library
Map Collection
Glossary of Cartographic Terms
From: Maps for
America. Third Edition.
- accuracy
- Degree of
conformity with a standard. Accuracy relates to the quality
of a result and is distinguished from precision which relates
to the quality of the operation by which the result is
obtained.
- adjustment
- Process designed to
remove inconsistencies in measured or computed quantities by
applying derived corrections to compensate for random or
accidental errors.
- adjustment, land-
line
- Positioning land lines on a map to indicate
their true, theoretical, or approximate location relative to
the adjacent terrain and culture, by reconciling the
information shown on Bureau of Land Management plats and
field records with the ground evidence of the location of the
lines.
- adjustment, standard
accuracy
- Adjustment of a survey resulting in values
for positions and (or) elevations that comply with the
National Map Accuracy
Standards.
- aerotriangulation
- The process of
developing a network of horizontal and or vertical positions
from a group of known positions using direct or indirect
measurements from aerial photographs and mathematical
computations.
- alidade
- Instrument, or part of
an instrument , for determining direction , either
horizontal or vertical . In its simplest form, a peepsight
or telescope mounted on a straightedge and used for plotting
directions graphically. In such instruments as transits and
theodolites, the alidade is the part containing the telescope
and its attachments.
- altimeter
- Instrument for
measuring altitudes or elevations with respect to a reference
level, usually mean sea level. The most common type is an
aneroid barometer. A radar altimeter determines the height
of an aircraft above the terrain by measuring the time
required for an electromagnetic pulse to travel from aircraft
to the ground and back.
- azimuth
- Horizontal
direction reckoned clockwise from the meridian plane.
- backshore
- Part of a beach that
is usually dry and is reached only by the highest tides; by
extension, a narrow strip of relatively flat coast bordering
the sea.
- base map
- See: map,
base.
- bathymetric map
- See: map,
bathymetric
- bathymetry
- Science of measuring
water depths (usually in the ocean) to determine bottom
topography.
- beach (seabeach)
- Zone of
unconsolidated material that extends landward from the low
water line to the place where there is marked change in
material or physiographic form, or to the line of permanent
vegetation (usually the effective lint of storm
waves).
- bench mark
- Relatively permanent
material object, natural or artificial, bearing a marked
point whose elevation above or below an adopted datum is
known.
- boundary monument
- Material object
placed on or near a boundary line to preserve and identify
the location of the boundary line on the
ground
- boundary survey
- Survey made to
establish or to reestablish a boundary line on the ground, or
to obtain data for constructing a map or plat showing a
boundary line.
- cadastral
map
- See: map, cadastral.
- cadastral
survey
- Survey relating to land boundaries, made to
create units suitable for title transfer or to define the
limitations of title. Derived from "cadastre" meaning a
register of land quantities, values, and ownership used
levying taxes, the term may properly be applied to surveys of
a similar nature outside the public lands, such surveys are
more commonly called "land surveys" or "property
surveys."
- cartography
- Science and art of
making maps and charts. The term may be taken broadly as
comprising all the steps needed to produce a map: planning,
aerial photography, field surveys, photogrammetry, editing,
color separation, and multicolor printing. Mapmakers,
however, tend to limit use of the term to the map-finishing
operations, in which the master manuscript is edited and
color separation plates are prepared for lithographic
printing.
- chain
- Unit of length equal to 66
feet, used especially in the U.S. public land surveys. The
original measuring instrument (Gunter's chain) was literally
a chain consisting of 100 iron links, each 7.92 inches long.
Steel-ribbon tapes began to supersede chains around 1900, but
surveying tapes are often still called "chains" and measuring
with a tape is often called "chaining." The chain is a
convenient unit in cadastral surveys because 10 square chains
equal 1 acre.
- chart
- Special-purpose map
designed for navigation or to present specific data or
information. The term "chart" is applied chiefly to maps
made primarily for nautical and aeronautical navigation, and
to maps of the heavens, although the term is sometimes used
to describe other special-purpose maps.
- chart,
aeronautical
- Charts designed to meet requirements of
aerial navigating, produced in several series, each on a
specified map projection and differing in scale, format, and
content, for use as dictated by type of aircraft and whether
flight is to be conducted under visual or instrument flight
rules.
- chart, bathymetric
- See: map,
bathymetric
- chart, nautical
- Representation of
a portion of the navigable waters of the Earth and adjacent
coastal areas on a specified map projection and designed
specifically to meet requirements for marine navigation.
Included on most nautical charts are depths of water,
characteristics of the bottom, elevations of selected
topographic features, general configurations and
characteristics of the coast, the shoreline (usually the mean
high water line), dangers, obstructions and aids to
navigation limited tidal data, and information about magnetic
variation in the charted area.
- choropleth
map
- See: map, choropleth
- clinometric
map:
- See: map, slope
- color
separation
- Process of preparing a separate drawing,
engraving, or negative for each color required in the
printing production of a map or
chart.
- compilation
- Preparation of a new or
revised map or chart, or portion thereof, from existing maps,
aerial photographs, field surveys, and other
sources.
- continuous tone
- Image not broken into
dots by photographic screen; contains unbroken gradient tones
from black to white, and may be either in negative or
positive form. Aerial photographs are examples of
continuous-tone prints. Contrasted with halftone (screened)
and line copy.
- contour
- Imaginary line on
ground, all points of which are at the same elevation above
or below a specific datum.
- contour
interval
- Difference in elevation between two adjacent
contours.
- control mapping
- Points of
established position or elevation, or both, which are used to
fix references in positioning and correlating map features.
Fundamental control is provided by stations in the national
networks of triangulation and traverse (horizontal control)
and leveling (vertical control). Usually it is necessary to
extend geodetic surveys, based on fundamental stations, over
the area to be mapped, to provide a suitable density and
distribution of control points. Supplemental control points
are those needed to relate the aerial photographs used for
mapping with the system of ground control. These points must
be positively photoidentified; that is, the points must be
positively correlated with their images on the
photographs.
- control station
- Point on the
ground whose position (horizontal or vertical) is known and
can be used as a base for additional survey
work.
- coordinates
- Linear and (or) angular
quantities that designate the position of a point in relation
to a given reference frame.
- coordinates, origin
of
- Points in a system of coordinates which serves as
a zero point in computing the system's elements or in
prescribing its use.
- culture
- Features
constructed by man that are under, on, or above the ground
which are delineated on a map. These include roads, trails,
buildings, canals, sewer systems, and boundary lines. In a
broad sense, the term also applies to all names, other
identification, and legends on a map.
- datum (pl. datums)
- In
surveying, a reference system for computing or correlating
the results of surveys. There are tow principal types of
datums: vertical and horizontal. A vertical datum is a level
surface to which heights are referred. In the United States,
the generally adopted vertical datum for leveling operations
is the National Geodetic Vertical Datum of 1929. The
horizontal datum is used as a reference for position. The
North American Datum of 1927 is defined by the latitude and
longitude of an initial point (Meade's Ranch in Kansas), the
direction of a line between this point and a specified
second point, and two dimensions that define the spheroid.
The new North American Datum of 1983 is based on a newly
defined spheroid (GRS80); it is an Earth-centered datum
having no initial point or initial direction.
- datum,
national geodetic vertical
See: national geodetic
vertical datum of 1929
- declination
- In
astronomy, the angular distance of a celestial body above
(north, plus) or below (south, minus) the celestial Equator.
Magnetic declination is the angular difference between
magnetic north and true (geographic) north at the point of
observation; it is not constant but varies with time because
of the "wandering" of the magnetic north pole.
- depth
curve
- Line on a map or chart connecting points of
equal depth below the datum.
- diazo
process
- Rapid method for copying documents in which
the image is developed by exposure to
ammonia.
- dike
- Bank of earth or stone used to
form a barrier, frequently and confusingly interchanged with
levee. A dike restrains water within an area that normally
is flooded. See levee.
- electronic distance measuring (EDM)
device:
- Instruments that measure the phase difference
between transmitted and reflected or retransmitted
electromagnetic waves of known frequency, or that measure the
round-trip transit time of a pulsed signal, from which
distance is computed.
- elevation
- Vertical
distance of a point above or below a reference surface or
datum.
- ellipsoid
- See:
spheroid
- engineering map
- See: map,
engineering
- ER-55 plotter
- Double-projection
plotting instrument utilizing ellipsoidal reflectors for
light projection.
- erosion
- Group of natural
processes including weathering, dissolution, abrasion,
corrosion, and transportation that remove material from any
part of the Earth's surface.
- estuary
- That
portion of a stream influenced by the tide of the body of
water into which it flows; an arm of the sea at a river
mouth.
- feature
separation
- Process of preparing a separate drawing,
engraving, or negative for selected types of data in the
preparation of a map or chart.
- flood control
map
- See: map, flood control
- flood
plain
- Belt of low flat ground bordering a stream
channel that is flooded when runoff exceeds the capacity of
the stream channel.
- forestry map
- See: map,
forestry
- formlines
- Lines, resembling contour
lines, drawn to present a conception of the shape of the
terrain without regard to a true datum or regular
spacing
- geodesy
- Science
concerned with the measurement and mathematical description
of the size and shape of the earth and its gravitational
fields. Geodesy also includes the large-scale, extended
surveys for determining positions and elevations of points,
in which the size and shape of the earth must be taken into
account.
- geoid
- Figure of the Earth visualized
as a mean sea level surface extended continuously through the
continents. It is a theoretically continuous surface that is
perpendicular at every point to the direction of gravity (the
plumbline).
- geologic map
- See: map,
geologic
- graticule
- Network of parallels and
meridians on a map or chart.
- graticule,
geographic
- System of coordinates of latitude and
longitude used to define the position of a point on the
surface of the Earth with respect to the reference
spheroid.
- grid
- Network of uniformly spaced
parallel lines intersecting at right angles. When
superimposed on a map, it usually carries the name of the
projection used for the map- that is, Lambert grid,
transverse Mercator grid, universal transverse Mercator
grid.
- hachure
- Any series
of lines used on a map to indicate the general direction and
steepness of slopes. The lines are short, heavy, and close
together for steep slopes; longer, lighter, and more widely
spaced for gentle slopes.
- halftone
- A picture
in which the gradations of light are obtained by the relative
darkness and density of tiny dots produced by photographing
the subject through a fine screen.
- high
water
- Maximum height reached by a rising tide. The
height may be due solely to the periodic tidal forces or it
may have superimposed upon it the effects of prevailing
meteorological conditions. Use of the "high tide" is
discouraged.
- high water line
- Intersection of
the land with the water surface at an elevation of high
water.
- high water mark
- Line or mark left upon
tidal flats, beach, or along shore objects indicating the
elevation or the intrusion of high water.
- hydrographic
survey
- Survey of water area, with particular
reference to submarine relief, and any adjacent land. See:
oceanographic survey
- hydrography
- Science that
deals with the measurement and description of the physical
features of the oceans, seas, lakes, rivers, and their
adjoining coastal areas, with particular reference to their
use for navigation.
- hydrology
- Scientific study
of the waters of the Earth, especially with relation to the
effects of precipitation and evaporation upon the occurrence
and character of ground water.
- hypsographic
map
- See: map,
hypsographic
- hypsography
- Topography referred
to the national geodetic vertical datum of 1929. The science
or art of describing heights of land surfaces with reference
to this datum.
- hypsometric map
- See: map,
hypsometric
- hypsometry
- Science or art of
determining terrain relief, by any method.
- imagery
- Visible representation
of objects and (or) phenomena as sensed or detected by
cameras, infrared and multispectral scanners, radar, and
photometers. Recording may be on photographic emulsion
(directly as in a camera or indirectly after being first
recorded on magnetic tape as an electrical signal) or on
magnetic tape for subsequent conversion and display on a
cathode ray tube.
- infrared scanner (thermal
mapper)
- Instrument that detects infrared radiation
and converts the detected energy to an electrical signal for
recording on photographic film or magnetic
tape.
- isogonic chart
- Chart showing isogonic
lines properly labeled with their magnetic
declination.
- isogonic line
- Line joining points
on the Earth's surface having equal magnetic declination as
of a given date.
- isopleth map
- See: map,
isopleth
- Kelsh
plotter
- Double-projection plotting instrument
utilizing swinging lamps to transmit light through contact-
size diapositives (positive transparencies).
- land use classification
system
- Coding system of categories and subcategories
designed for use on a map to designate land or water
use.
- land use map
- See: map, land
use
- landmark
- Monument of material mark or
fixed object used to designate a land boundary on the ground:
any prominent object on land that may be used to determine a
location or a direction in navigation or
surveying.
- latitude
- Angular distance, in
degrees, minutes, and seconds of a point north or south of
the Equator.
- lead line
- Line weighted with lead
for making depth soundings in water.
- levee
-
Artificial bank confining a stream channel or limiting
adjacent areas subject to flooding; an embankment bordering a
submarine canyon or channel, usually occurring along the
outer edge of a curve.
- level surface
- Surface
which at every point is perpendicular to the plumbline or the
direction in which gravity
acts.
- leveling
- Surveying operation in which
heights of objects and points are determined relative to a
specified datum.
- line copy (line drawing)
Map copy
suitable for reproduction without the use of a screen; a
drawing composed of lines as distinguished from continuous-
tone copy.
- line map
- See: map,
line
- longitude
- Angular distance, in degrees,
minutes, and seconds, of a point east or west of the
Greenwich meridian.
- low water:
- Minimum height
reached by a falling tide. The height may be due solely to
the periodic tidal forces or it may have superimposed upon it
the effects of meteorological conditions.
- low water
line
- Intersection of the land with the water surface
at an elevation of low water. Not to be confused with mean
low water line.
- magnetic
declination
- See:
declination
- map
- Graphic representation of the
physical features (natural, artificial, or both) of a part or
the whole of the Earth's surface, by means of signs and
symbols or photographic imagery, at an established scale, on
a specified projection, and with the means of orientation
indicated.
- map, base
- Map on which information
may be placed for purposes of comparison or geographical
correlation. The term "base map" was at one time applied to
a class of maps now known as outline maps. It may be applied
to topographic maps, also termed "mother maps" that are used
in the construction of other types of maps by the addition of
particular data.
- map, bathymetric
- Maps
delineating the form of the bottom of a body of water, or a
portion thereof, by the use of depth contours
(isobaths).
- map, cadastral
- Map showing the
boundaries of subdivisions of land, often with the bearings
and lengths thereof and the areas of individual tracts, for
purposes of describing and recording ownership. It may also
show culture, drainage, and other features relating to land
use and value. See:plat
- map,
choropleth
- Thematic map in which areas are colored,
shaded, dotted, or hatched to create darker or lighter areas
in proportion to the density of distribution of the theme
subject.
- map digitization
- Conversion of map
data from graphic to digital form.
- map,
engineering
- Map showing information that is essential
for planning an engineering project or development and for
estimating its cost. It usually is a large-scale map of a
small area or of a route. It may be entirely the product of
an engineering survey, or reliable information may be
collected from various sources for the purpose, and assembled
on a base map.
- map, flood control
- Map designed
for studying and planning control projects in areas subject
to flooding.
- map, forestry
- Map prepared
principally to show the size, density, kind, and value of
trees in a designated area.
- map, geologic
- Map
showing the structure and composition of geologic
features.
- map hypsographic
- Map showing relief
with elevations referred to the national geodetic
vertical datum of 1929.
- map, hypsometric
- Map
showing relief by any convention, such as contours, hachures,
shading, or tinting.
- map, isopleth
- Map
consisting of lines connecting places of equal value of
distribution for a given theme such as rainfall or
temperature.
- map, land use
- Map showing by
means of a coding system the various purposes for which
parcels of land are being used by man.
- map,
line
- Map composed of lines as distinguished from
photographic imagery.
- map,
orthophotographic
- See: orthophotographic
map
- map, photographic
- See:
photomap
- map, planimetric
- Map that presents
only the horizontal positions for features represented.
distinguished from a topographic map by the omission of
relief in measurable form. The features usually shown on a
planimetric map include rivers, lakes, and seas; mountains,
valleys, and plains; forests, and prairies; cities, farms
transportation routes, and public utility facilities; and
political and private boundary lines. A planimetric map
intended for special use may present only those features
essential to the purpose to be served.
- map
projection
- Orderly system of lines on a plane
representing a corresponding system of imaginary lines on an
adopted terrestrial or celestial datum surface. Also, the
mathematical concept for such a system. For maps of the
Earth, a projection consists of 1) a graticule of lines
representing parallels of latitude and meridians of longitude
or 2) a grid.
- map series
- Family of maps
conforming generally to the same specifications and designed
to cover an area or a country in systematic
pattern.
- map, slope (clinometric map)
- Map
showing the degree of steepness of the Earth's surface by the
use of various colors or shading for critical ranges of
slope.
- map, soil
- Map that shows the
constitution, structure, and texture of the soil and
identifies ongoing erosion.
- map, storm
evacuation
- Map designed to identify coastal areas
subject to flooding, to indicate recommended areas of refuge,
and to emphasize available evacuation routes.
- map,
thematic
- Map designed to provide information on a
single topic, such as geology, rainfall,
population.
- map, topographic
- Map that present
the horizontal and vertical positions of the features
represented; distinguished from a planimetric map by the
addition of relief in measurable form.
- marsh,
coastal
- Area of salt-tolerant vegetation in brackish
and (or) saline-water habitants subject to tidal
inundation.
- marsh, freshwater
- Tract of low wet
ground, usually miry and covered with rank
vegetation.
- mean high water
- Tidal datum that
is the arithmetic mean of the high water heights observed
over a specific 19-year Metonic cycle (National Tidal
Datum Epoch). For stations with shorter series, simultaneous
observations are made with a primary control tide station to
derive the equivalent of a 19-year value. Use of "mean high
tide" is discouraged.
- mean high water
line
- Intersection of the land with the water surface
at the elevation of high water. See: shoreline
- mean
low water
- Tidal datum that is the arithmetic mean of
the low water heights observed over a specific 19-year
Metonic cycle (National Tidal Datum Epoch). For
stations with shorter series, simultaneous observations are
made with a primary control tide station to derive the
equivalent of a 19-year value. Use of "mean low tide" is
discouraged.
- mean low water line
- Intersection
of the land with the water surface at the elevation of low
water.
- mean sea level
- Tidal datum that is the
arithmetic mean of the hourly water elevations observed over
a specific 19-year Metonic cycle (National Tidal Datum
Epoch). Shorter series are specified in the name; that is,
monthly mean sea level and yearly mean sea level. See:
datum
- meander line
- Metes-and-bounds traverse
approximately along the mean high water line of a
permanent body of water. By following the sinuosities of the
bank or shoreline, the meander line provides data for
computing the area of land remaining after the water area has
been segregated. A meander line differs from other metes
and bounds surveys in that it does not ordinarily
determine or fix
boundaries.
- meanderable
- Capable of being
depicted by reference to a meander
line.
- meridian
- Great circle on the surface of
the Earth passing through the geographical poles and any
given point on the Earth's surface. All points on a given
meridian have the same longitude.
- metes and
bounds
- Method of describing land by measure of length
(metes) of the boundary lines (bounds).
- Metonic
cycle
- Period of 235 lunations or about 19 years.
devised by Meton, an Athenian astronomer (5th century B.C.)
for the purpose of obtaining a period at the end of which the
phases of the moon recur in the same order and on the same
days as in the preceding cycle.
- metric
system
- Decimal system of weights and measures based
on the meter as a unit length and the kilogram as a unit
mass.
- monoscopic
- Pertaining to the observation
of a single photograph or other view.
- monument
(surveying)
- Permanent physical structure marking the
location of a survey point. Common types of monuments are
inscribed metal tablets set in concrete posts; and metal rods
driven in the ground.
- mosaic, aerial
- Assembly
of aerial photographs whose edges usually have been torn or
cut selectively and matched to the imagery on adjoining
photographs to form a continuous representation of a portion
of the Earth's
surface.
- multiplex
- Stereoplotter of the
double-projection type characterized by its use of reduced-
scale diapositives and stationary lamphouses with condensing
lenses.
- multispectral scanner (MSS)
- Device for
sensing radian energy in several channels of the
electromagnetic spectrum.
- national geodetic vertical datum of
1929
- Reference surface established by the U.S. Coast
and Geodetic Survey in 1929 as the datum to which relief
features and elevation data are referenced in the
conterminous United States; formerly called "mean sea level
1929."
- National Map Accuracy
Standards
- Specifications promulgated by the U.S.
Office of Management and Budget to govern accuracy of
topographic and other maps produced by Federal
Agencies.
- navigable waters
- Water usable, with
or without improvements, as routes for commerce in the
customary means of travel on
water.
- neatline
- Line separating the body of a
map from the map margin. On a standard quadrangle
map, the neatlines are the meridians and parallels delimiting
the quadrangle.
- oceanic
survey
- Survey or examination of condition in the
ocean or any part of it, with reference to animal or plant
life, chemical elements present, temperature gradients, etc.
See: hydrographic
survey
- offshore
- Comparatively flat zone of
variable width that extends from the outer margin of the
rather steeply sloping shoreface to the edge of the
continental shelf.
- orientation
- Establishing
correct relationship in direction with reference to points of
the compass; the state of being in correct relationship in
direction with reference to the points of the
compass.
- origin of coordinates
- Point in a
system of coordinates that serves as a zero point in
computing the system's elements or in prescribing its
use.
- orthophotograph
- Photograph having the
properties of an orthographic projection. It is derived from
a conventional perspective photograph by simple or
differential rectification so that image displacements caused
by camera tilt and terrain relief are
removed.
- orthophotographic map
- Map produced by
assembling orthophotographs at a specified uniform scale in a
map format.
- orthophotomap
- Orthophotographic
map with contours and cartographic treatment, presented in a
standard format, and related to standard reference
systems.
- orthophotoquad
- Monocolor
orthophotgraphic map presented in a standard quadrangle
format and related to standard reference systems. It has no
contours and little or cartographic
treatment.
- orthophotoscope
- Photomechanical
device used in conjunction with a double-projection
stereoplotter for producing
orthophotograph.
- overedge
- Any portion of a map
lying outside the nominal map border
(neatline).
- overlay
- Printing or drawing
on a transparent or translucent medium intended to be placed
in register on a map or other graphic and which shows details
not appearing or requiring special emphasis on the base
material.
- overprint
- New material printed on a
map or chart to show data of importance or special use, in
addition to those data originally printed.
- parallel of latitude
- A circle,
or approximation of a circle, on the surface of the Earth,
parallel tot he Equator, and connecting points of equal
latitude; a circle of the celestial sphere parallel to
the ecliptic, and connecting points of equal celestial
latitude.
- photogrammetry
- Science or art of
obtaining reliable measurements or information from
photographs or other sensing systems.
- photomap
(photographic map)
- Map made by adding marginal
information, descriptive data, and a reference system to a
photograph or assembly of
photographs.
- plain
- Region of uniform general
slope, comparatively level, of considerable extent, and not
broken by marked elevations and depressions (it may be an
extensive valley floor or a plateau summit); an extent of
level or nearly level land; a flat, gently sloping, or nearly
level region of the sea
floor.
- planetable
- Instrument consisting
essentially of a drawing board on a tripod and some type of
sighting device (alidade) with attached straightedge,
used for plotting the lines of survey directly from
observation in the field.
- planimetric map
- See:
map, planimetric
- planimetry
- Plan details of a
map - those having no indication of relief or
contour.
- plat
- Diagram drawn to scale showing
all essential data pertaining to the boundaries and
subdivisions of a tract of land, as determined by survey or
protraction. As used by the Bureau of Land Management, the
drawing which represents the particular area included in a
survey, such as township, private land claim, or mineral
claim, and the lines surveyed, established, or retraced,
showing the direction and length of each such line; The
relation to the adjoining official surveys; the boundaries,
descriptions, and area of each parcel of land subdivided;
and, as nearly as may be practicable, a representation of the
relief and improvements within the limits of the
survey.
- prime meridian
- Meridian of longitude 0
degrees, used as the origin for measurements of
longitude. The meridian of Greenwich, England, is the
internationally accepted prime meridian on most charts.
However, local or national prime meridians are occasionally
used.
- projection, map
- See: map,
projection
- public land system
- Public lands are
subdivided by a rectangular system of surveys established and
regulated by the Bureau of Land Management. The standard
format for subdivision is by townshipsmeasuring 6
miles (480 chains) on a side. Townships are further
subdivided into 36 numbered sections of 1 square mile (640
acres) each.
- quad-centered
photograph
- Middle exposure of a phototriplet (three
consecutive aerial photographs) take so that the middle
photograph is exposed directly above the center of the
quadrangle and the preceding and following photographs
are exposed directly above the boundaries of the quadrangle.
The flying height is set such that the quad-centered
photograph covers the entire
quadrangle.
- quadrangle
- Four-sided area,
bounded by parallels of latitude and
meridians
of longitude used as an area unit in mapping (dimensions are
not necessarily the same in both directions). Also, a
geometric figure of significance in geodetic
surveying.
- radial-line
plotting
- Determination of the location of points by
the successive intersection and resection of direction lines
radiating from the radial centers of overlapping aerial
photographs.
- rectification, differential
- The
process of scanning and reprojecting a photograph onto a
horizontal plane in differential elements to remove
displacements caused by tilt and relief. The process may be
accomplished by any one of a number of instruments developed
specifically for the purpose.
- rectification,
simple
- Projection of an aerial photograph
(mathematically, graphically, or photographically) from its
plane onto a horizontal plane by translation, rotation, and
(or) scale change to remove displacement due to tilt of the
camera.
- relief
- Elevations and depressions of
the land or sea bottom.
- relief
shading
- Technique for making hypsography on a map
appear three dimensional by the use of graded shadow effects.
Generally, the features are shaded as though illuminated from
the northwest.
- remote sensing
- Process of
detecting and (or) monitoring chemical or physical properties
of an area by measuring its reflected and emitted
radiation.
- representational fraction
- Scale of
a map or chart expressed as a fraction or ratio that relates
unit distance on the map to distance measured in the same
unit on the ground.
- reproduction
- Summation of
all processes involved in printing copies from an original
drawing. A printed copy of an original drawing made by the
processes of reproduction
- scale
- Relationship existing
between a distance on a map, chart, or photograph and the
corresponding distance on the Earth.
- sea level (water
level)
- Height of the surface of the sea at any given
time.
- section
- Unit of subdivision of a
township; normally a quadrangle 1 mile square with
boundaries conforming to meridians and
parallels within established limits, and containing
640 acres as nearly as
practicable.
- sensor
- Technical means, usually
electronic, to extend man's natural senses by detecting
emitted or reflected energy. The energy may be nuclear,
electromagnetic (including the visible and invisible portions
of the spectrum), chemical, biological, thermal, or
mechanical
- shoreline
- Intersection of the land
with the water surface.
- slope map
- See: map,
slope
- soil map
- See: map,
soil
- spheroid
- Mathematical figure closely
approaching the geoid in form and size and used as a surface
of reference for geodetic surveys. A reference spheroid or
ellipsoid is a spheroid determined by revolving an ellipse
about its shorter (polar) axis and used as a base for
geodetic surveys of a large section of the Earth (such as the
Clarke spheroid of 1866 which is used for geodetic surveys in
the United States).
- spot elevation
- Point on a
map or chart whose height above a specified datum is noted,
usually by a dot or a small sawbuck and elevation value.
Elevations are shown, on a selective basis, for road forks
and intersections, grade crossings summit of hills, mountain
- stadia
- Technique of distance measurement
wherein the observer reads the intercept subtended on a
graduated rod between two marks on the reticle of the
telescope.
- standard-accuracy adjustment
- See:
adjustment, standard-accuracy
- state plane coordinate
system
- Coordinate systems established by the U.S.
Coast and Geodetic Survey (now the National Ocean Survey),
usually one for each state, for use in defining positions of
points in terms of plane rectangular (x,y)
coordinates.
- stereocompilation
- Production of a
map or chart manuscript from aerial photographs and geodetic
control data by means of photogrammetric
instruments.
- stereoplotter
- Instrument for
plotting a map by observation of stereomodels formed by pairs
of photographs.
- stereoscopic
- Pertaining to the
use of binocular vision for observation of a pair of
overlapping photographs or other perspective views, giving
impression of depth.
- storm evacuation map
- See:
map, storm evacuation
- subsidence
- Decrease in
the elevation of land surface due to tectonic, seismic, or
artificial forces, without removal of surface
material.
- survey
- Orderly process of
determining data relating to any physical or chemical
characteristics of the Earth. The associated data obtained
in a survey. An organization engaged in making a
survey.
- tacheometer
(tachymeter)
- Surveying instrument designed for use in
the rapid determination of distance, direction, and
difference of elevation from a single observation, using a
short base which may be an intergraph part of the
instrument.
- thematic map
- See: map,
thematic
- theodolite
- Precision surveying
instrument for measuring horizontal and vertical
angles.
- tide
- Periodic rise and fall of the
water resulting from gravitational interactions between the
Sun, Moon, and Earth. The vertical component of the
particulate motion of a tidal wave. Although the
accompanying horizontal movement of the water is part of the
same phenomenon, it is preferable to designate this motion as
tidal current.
- topographic map
- See: map,
topographic
- topography
- Configuration (relief)
of the land surface; the graphic delineation or portrayal of
that configuration in map form, as by contour lines; in
oceanography the term is applied to a surface such as the sea
bottom or surface of given characteristics within the water
mass.
- township
- Unit of survey of the public
lands of the United States, normally a quadrangle
approximately 6 miles on a side with boundaries conforming to
meridians and parallels within established
limits, containing 36 sections. Also, in minor governmental
subdivision.
- transit
- Precision surveying
instrument; a theodolite in which the telescope can be
reversed in direction by rotation about its horizontal
axis.
- traverse
- Sequence of lengths and
directions of lines connecting a series of stations, obtained
from field measurements, and used in determining positions of
the stations.
- triangulation
- Method of
extending horizontal position on the surface of the Earth by
measuring the angles of triangles and the included sides of
selected triangles.
- trilateration
- Method of
surveying wherein the lengths of the triangle sides are
measured, usually by electronic methods, and the angles are
computed from the measured lengths. Compare with
triangulation.
- Universal
Transverse Mercator (UTM) grid
- Military grid system
based on the transverse Mercator projection, applied to maps
of the Earth's surface extending from the Equator to 84
Degrees north and 80 degrees south
latitudes
- upland
- Highland; ground elevation
above the lowlands along rivers or between hills.
- zenith
telescope
- Instrument for observing starts near the
zenith (a point on the celestial sphere directly above the
observer's position).