Logged In Members Do Not See Ads

Land Surveyor Jobs Available


GEO Ambassador

ABCs of GPS and Mapping

ABCs of Mapping and GPS

Can we (as a group) create the most comprehensive glossary of GPS and Mapping known to man?  I want you all to think about this, because it is within our reach.   From now until the end of the month, I will be posting 3 letters of the alphabet and all of the words related to GPS and mapping that I can dig up to fall under those letters.  Would I would like to try is a collaboration with all of the brilliant land surveyors on LSU, to compile the most complete and thorough Glossary of GPS and Mapping known to man, to be available both online and in print for our future generations.  This glossary will be translated into all other major languages and should include terms known to surveyors and civil engineers in all parts of the world.  This could be exciting collaboration project and will be very valuable in years to come.  I invite all of you to add your terms and you will receive credit and a link to your site for submitting a term.

Let's Keep it in This Discussion
When I list 3 letters and what I've dug up to fit within those letter, please come behind me and add words that you know along with a definition or description.  If you care to have a link to your site for your submission, please attach link at the end of your posted term or terms. Also, if you are adding a term for a letter which has already been covered, start your post like this:
Term-the definition or description of you GPS and/or Mapping term

Let's Begin!


acquisition time - see TTFF
active antenna - An amplified antenna
active leg - The segment of the route currently being traveled.
agonic line - An imaginary line on the earth's surface connecting points where the magnetic declination is zero.
AGPS - Assisted Global Positioning System - A land station assists GPS in acquiring position.
almanac data - Orbital position data for each GPS satellite. Considered not to be very accurate as the data are valid for over one month.
altimeter - An instrument that measures altitude or elevation with respect to areference level, usually mean sea level, by means of air pressure.
APRS- Automatic Position Reporting System - An amateur radio based
automatic position reporting system for tracking and digital

arcGIS - A family of software products that form a complete GIS (Geographic Information System).
archipelago - A large group of islands.
arcInfo - Comprehensive software in the arcGIS family that has advanced geoprocessing and data conversion capabilities.
arete - A sharp, narrow mountain ridge or spur.
ARGOS- Advanced Research and Global Observation Satellite - An advanced
research and development satellite launched by the United States Air
Force. Carries various space and atmospheric experiments.

atoll - A ringlike coral island and reef that nearly or entirely encloses a lagoon.
automatic vehicle location - A system of providing real-time location information for emergency vehicles, delivery trucks, service vehicles, etc.
AVL - See automatic vehicle location.
azimuth - The horizontal angle (0 - 360 degrees) from a reference point, usually true north or true south. Also known as a bearing.
azimuth ring - The dial on a compass, marked with zero to 360 degree markings.


barranca - A dry ravine or a steep depression between hills.
bathymetry - The measurement of depth of bodies of water.
bearing - An azimuth; a horizontal direction of a line or direction of travel with true north or true south as a reference.
bench mark - A material object, natural or man-made, with a known elevation orhorizontal location. Bench marks can be used as reference points when
traveling a route or in determining the elevation of nearby land

bitmap image - An image with 1 bit of color information per pixel, also known as a bitmapped image.
Bluetooth- A standard of radio technology that makes it possible to transmit
signals over short distances between telephones, computers and other

bosk - A small, wooded area.
bourn - A small stream.
bourne - Same as bourn.
BTGPS - Bluetooth GPS - See Bluetooth.


C/A code - Coarse Acquisition code - The GPS signal for civilian use (also used by the military to get an initial fix).
cadastre - A public record, survey, or map of the value , extent, and ownership of land as a basis of taxation.
calibration - The process of associating map information held in an image file withits location on the earth so that, for example, each pixel becomes
associated with a latitude and longitude allowing routes and tracks to
be correctly plotted and displayed.

carrier-aided tracking - A method to improve accuracy by using the GPS carrier signal to get a more precise lock on the pseudorandom code.
cartography - The art or technique of making maps or charts.
CEP- Circular Error Probable - The radius of a circle within which fifty
percent of positioning solutions fall. CEP is used to achieve horizontal

CF- Compact Flash - A standard that PDAs, laptops, and other
computer-related devices use to accept removable accessories such as
additional memory or GPS receivers.

channel - Circuitry necessary to receive the signal from one GPS satellite.
chartplotter - A device that overlays GPS data on to marine navigational charts.
circular error probable - See CEP.
Clarke 1866 - The reference spheroid for the NAD27 coordinate system.
clinometer - A device, usually similar to a compass, used to measure vertical angles, as in the slope of a hill.
CMG - see course made good
COG - see course over ground
cold start - The ability of a GPS receiver to start giving position data without any almanac data stored in its memory.
collar- The area surrounding the actual map itself containing necessary
information such as scale, legend, latitude and longitude, etc.

compact flash - See CF.
constellation - 1) All GPS satellites. 2) The satellites visible to a GPS receiver at one time.
continental margin- The zone of transition from a continent to the adjacent ocean basin.
It usually includes a continental shelf, continental slope, and
continental rise.

continental rise - The gently sloping surface located at the base of a continental slope.
continental shelf - The submerged margin of a continental mass extending from the shore to the first prominent break in slope.
continental slope- The slope that extends from a continental shelf down to the ocean
basin. In some areas, such as off eastern North America, the continental
slope grades into the more gently sloping continental rise.

contour interval - The difference, in feet or meters, in elevation between two adjacent contour lines.
contour line - A line on a topographic map that represents a specific elevation.
control point- Also called a control station. Locations on the earth's surface used
for mapping references. Can be horizontal or vertical or both. Often
these are bench marks.

CONUS - Contiguous (or Continental) United States.
coordinates - A set of numbers that represents a precise location anywhere on Earth. Usually stated as latitude and longitude.
course - The direction from the starting waypoint or location to the destination waypoint, measured in degrees.
course made good- The bearing from the "active from" waypoint to the current position,
independent of the path taken to arrive at the current position.

course over ground - The direction of movement relative to the Earth.
crosstrack error - The lateral distance in either dirction you are off the desired course.


datum - (pl. datums) A model of the earth's surface that is comprised of a network of physical points that serves as a reference for maps, for both horizontal and vertical data. In the U.S. early topographic maps were based on the North American Datum 1927 (NAD27). More recent maps are based on a North American Datum 1983 (NAD83). GPS uses a datum called World Geodetic System 1984 (WGS84). There are over 100 datums in use around the world.
dead reckoning - The technique of determining position by computing distance traveled on a given course. Distance traveled is determined by multiplying speed by elapsed time.
degree - A unit of measurement; 360 degrees equal one complete circle, as around the earth on a line of latitude; measured from 0 to 90 degrees from the equator to each pole along a line of longitude.
depression - An area in the surface of the earth that is lower in elevation than the surrounding area; a hole.
depression contour - A contour line with hachures (small perpendicular tick marks) to signify a depression.
DGN - microstation design file - A file format/extension.
DGPS - Differential GPS - A method of improving GPS accuracy using measurements at a known location to improve the measurements made by other GPS receivers within the same general area.
dingle - A small, wooded valley.
DMA - Defense Mapping Agency - Former name for the National Imagery and Mapping Agency (NIMA).
donga - A gully in a veldt.
DOQQ - Digital Orthophoto Quarter-Quadrangle - 1:12,000 scale representations of a quarter of the area of a conventional USGS 7.5 minute topographical map.
draw - A small, natural depression or valley in the side of a hill; a gully.
DRG - Digital Raster Graphics - See "Raster Maps."
DTAM - Digital world Tectonic Activity Map.
DTM - Digital Terrain Model - A digital model of the terrain surface - similar to a DEM but often enhanced by planimetric information.
DXF - Drawing eXchange Format - Used for transfering CAD (Computer Aided Drafting) files.


ECDIS - Electronic Charting Display Information System - A system with sufficient precision that commercial navigation can be accomplished without the aid of paper charts.
ECEF coordinates - Earth Centered Earth Fixed coordinate system where the positive X axis lies on the equatorial plane passing through the prime meridian (Greenwich), the positive Y axis lies on the equatorial plane at 90 east, and positive Z passes north through the mean rotational axis of the earth.
EGNOS - European Geostationary Navigation Overlay Service - A European system of satellite navigation. It will augment the two satellite navigation systems now operating, the U.S. GPS and GNSS systems. It consists of three geostationary satellites and a network of ground stations. EGNOS will achieve its aim by transmitting a signal containing information on the reliability and accuracy of the positioning signals sent out by GPS and GNSS.
elevation - The vertical distance of a point above or below a reference surface, usually sea level.
ellipsoid - The mathematical function used to describe the shape of the earth for geodetic computations.
EPE - Estimated Position Error - The distance the GPS receiver may be off target.
ephemeris data - Precise orbital position and clock data for each GPS satellite. Valid for about 30 minutes.
equator - An imaginary line around the Earth at 0 degrees latitude.
ETE - Estimated Time Enroute - The time left to the destination at the present speed.


fall line - A line connecting the waterfalls of nearly parallel rivers that marks a drop in land level.
Federal Geographic Data Committee - See FGDC.
FDGC - Federal Geographic Data Committee - An agency established by the United States Federal Office of Management and Budget responsible for the coordination of development, use, sharing, and dissemination of surveying, mapping, and related spatial data.
fjord - (also fiord) - A long, narrow inlet of the sea between steep slopes.
flume - A narrow gorge, especially one with a stream.
fluxgate compass - An electronic device used to measure magnetic direction.
ford - A shallow place in a body of water, such as a river, where one can cross on foot, by riding an animal, or in a vehicle.
form factor - A term used to describe the way a device is constructed, such as its shape. For example, GPS receivers come in many form factors, such as handheld, PDA, automotive, USB, etc.
FRS - Family Radio Service - A walkie talkie system authorized in the United States since 1996 that uses UHF frequencies.

You need to be a member of Land Surveyors United - Global Surveying Community to add thoughts!

Join Land Surveyors United - Global Surveying Community

Votes: 0
Email me when people reply –


This reply was deleted.

Answer As your Facebook Page

Latest Discussions by Category


You are not logged in


Land Surveyor Community Forum

Most land surveying related topics are evergreen - meaning the topics of discussion are many times timeless.  If you have a question regarding Land Surveying in general, this is the place to ask your questions.    

Add Discussion

Global Forums

Hey there!
It looks like you are enjoying the community content.

That's nice! Please don't forget to mention us if you use what you just copied on your website. Help strenthen the community by linking back to us!

Thank you very much! Have a nice day! :)

Ok. Don't bother me again, for this session.