NJ Land Surveyor key terms

A reference surface or set of parameters against which positions and elevations are measured, such as NAD83 for horizontal coordinates or NAVD88 for elevations. Changing datums shifts published coordinate values.

A mathematically defined, flattened sphere used to model the size and shape of the Earth for geodetic computations. Different regions historically adopted different ellipsoids, so coordinates depend on which one was used.

The equipotential surface of the Earth's gravity field that approximates mean sea level, extended through the continents. Orthometric heights are measured relative to it, while ellipsoid heights are measured above the ellipsoid.

The elevation of a point above the geoid, measured along a plumb line. It is the elevation used in everyday surveying and mapping, unlike the purely geometric ellipsoid height produced by GNSS.

The reference surface from which elevations are referenced, such as NAVD88 in the conterminous United States. Tidal, leveling, and GNSS-derived vertical datums differ, and mixing them introduces systematic elevation errors.

A monumented point of known elevation, or of known horizontal position, used as a reference for surveys. Its published value is tied to a specific datum and must be checked for stability and current adjustment.

A physical object set in the ground to mark and preserve a survey point, such as a rebar with cap, pipe, or concrete post. Its position, description, and accessories support boundary and control evidence.

A system of projected coordinate zones defined for each state to give plane coordinates with low distortion. Each zone uses a specified map projection, datum, and unit, and coordinates are not interchangeable between zones.

A mathematical transformation that converts positions on the curved Earth surface into plane coordinates. Common survey projections include transverse Mercator and Lambert conformal conic, each preserving selected properties at the cost of distortion.

The ratio between a distance on the projection grid and the corresponding distance on the reference ellipsoid or at ground level. Grid, elevation, and combined factors must be applied when converting between measured and mapped distances.

The direction of a line measured on the projection grid, referenced to grid north rather than true or magnetic north. The difference from geodetic azimuth is the convergence angle, which grows with distance from the central meridian.

A horizontal direction expressed as an angle measured clockwise from a stated reference meridian, usually north, through 360 degrees. Bearings are the equivalent expressed as quadrant angles.

A direction stated as an acute angle from north or south toward east or west, such as N 45 E. It describes the same line as an azimuth but is confined to a quadrant.

A survey in which connected courses of measured angles and distances establish the positions of successive points. It may be closed on itself or on known control, and misclosure indicates accumulated error.

The northing and easting components of a traverse course, computed as distance times the cosine and sine of the bearing. Summing them around a closed traverse reveals the linear misclosure.

The discrepancy between a computed survey and a known or starting value, expressed as angular or linear misclosure. It is compared against an allowable tolerance to judge whether the work is acceptable.

A differential leveling run that begins and ends on known elevations, allowing the accumulated error to be measured. Misclosure is distributed among the setups in proportion to the distances run.

The process of determining elevation differences by reading a graduated rod through an instrument set between points. Backsight and foresight readings are subtracted to give the change in elevation between them.

An electronic instrument combining an angle-measuring theodolite with an electronic distance meter and onboard computing. It records horizontal and vertical angles and slope distances, from which coordinates are computed.

A method of measuring distance by timing or phase-comparing a modulated light or microwave signal traveling to a reflector and back. Accuracy depends on instrument calibration and atmospheric correction.

A correction for the offset between the physical center of a reflector and the point to which the instrument's distance measurement is referenced. Entering the wrong value biases every measured distance.

An adjustment applied to electronic distance measurements to account for temperature, pressure, and humidity differing from the instrument's reference conditions. Ignoring it produces small but systematic distance errors.

Global Navigation Satellite System, a family of satellite positioning systems including GPS, GLONASS, Galileo, and BeiDou. Survey-grade positioning uses carrier-phase observations and differential techniques for centimeter accuracy.

Real-Time Kinematic positioning, in which a rover receives corrections from a base station to resolve carrier-phase ambiguities and produce centimeter-level coordinates in the field. It requires adequate satellite geometry and radio or network link.

A point whose position is determined by the traverse, usually marked by an instrument setup and often by a monument. Stations carry coordinates computed from the measured angles and distances.

A network of points with known horizontal coordinates that serves as the framework for other surveys. It may be geodetic, established by GNSS or triangulation, or local, established by traverse.

A point that marks a boundary line terminus or change in direction, often evidenced by a monument, bearing tree, or natural feature. Its location and legal status are central to boundary determination.

A map of a survey or subdivision showing boundaries, lots, easements, and monuments, prepared for recording. Once recorded, it can create or affect property rights and is often the controlling description.

A right held by one party to use another's land for a specific purpose, such as access or utilities, without owning it. It may be appurtenant or in gross and is typically shown on plats and described in deeds.

The minimum distance a structure must be placed from a property line, street, or other feature, as required by zoning or plat restrictions. Surveyors locate lines and improvements to verify compliance.

A strip of land over which a road, railroad, or utility has a legal right of passage, either owned in fee or held as an easement. Its limits define the boundary between public and private interests.

A property description that defines boundaries by courses, distances, and monument references rather than by lot and block. It typically begins at a point of beginning and returns to it in a closed perimeter.

The starting point of a metes and bounds description from which the boundary courses are traced and to which they should return. Ambiguity or error at this point propagates through the entire description.

A doctrine under which a person can acquire title to land through open, notorious, exclusive, hostile, and continuous possession for a statutory period. Surveyors may be asked to document occupancy evidence relevant to such claims.

A detailed survey prepared to a national standard for title insurance and lending purposes, showing boundaries, improvements, easements, and specified optional items. It requires careful research and field evidence, and its table of contents defines scope.

The science of deriving measurements and maps from photographs, now often from aerial or drone imagery. Stereoscopic overlap and ground control allow three-dimensional positions to be computed.

Light detection and ranging, a remote sensing method that measures distances by laser pulses to produce dense point clouds. It is used for terrain models, corridor mapping, and feature extraction.

An aerial photograph that has been geometrically corrected so that it has a uniform scale and can be used as a map. It is often combined with contours and planimetric data in mapping products.

A digital representation of ground surface elevations, often stored as a grid or triangulated irregular network. It supports volume computations, drainage analysis, and design work.

A line on a map connecting points of equal elevation. Contour interval and shape convey slope steepness and terrain form, and contours must be based on accurate vertical control.

The numerical difference between a computed value and a known or starting value at the end of a survey. It is typically compared with a standard tolerance and may be adjusted before coordinates are finalized.