ID Land Surveyor key terms

The direction of a line stated as an angle measured from either north or south toward east or west, always between 0 and 90 degrees, with the quadrant named (for example N45E).

The horizontal direction of a line measured clockwise from a chosen reference meridian, usually north, through a full circle from 0 to 360 degrees.

A reference line of constant direction used to measure bearings and azimuths, commonly true north, magnetic north, or an assumed grid direction for a project.

The angle between magnetic north and true north at a given place and time; it changes slowly with location and year and must be applied to convert compass readings to true directions.

A survey in which lengths and directions of a series of connected lines are measured to determine coordinates of points, either closing on a known point or ending open.

The northing (latitude) and easting (departure) components of a traverse line, computed as distance times cosine or sine of the line's bearing or azimuth.

The difference between computed ending coordinates and known ending coordinates of a traverse; expressed as linear misclosure and often converted to a relative precision ratio.

A traverse that begins and ends at points of known position, or returns to its starting point, allowing misclosure to be computed and adjusted.

A traverse adjustment method distributing latitude and departure misclosure in proportion to each course length, commonly called the compass rule and used for surveys of similar relative precision.

A statistical method that adjusts survey observations so the sum of squared residuals is minimized, providing adjusted coordinates and estimates of their uncertainty.

The difference between an observed value and the value computed or adjusted from a mathematical model; residuals reveal random error patterns in a survey network.

A graphical representation of positional uncertainty at a point, showing the size and orientation of the confidence region derived from the covariance of adjusted coordinates.

A reference framework defining the position and orientation of a coordinate system on the Earth, such as NAD83 or a modern national realization, to which horizontal coordinates are tied.

A system of plane rectangular coordinates defined by map projections for each state, designed to keep distortion small and allow surveyors to use simple plane computations.

A mathematical transformation that converts positions on the curved Earth surface to a flat grid, introducing scale distortion that varies across the mapped area.

The ratio between a distance on a map projection grid and the corresponding distance on the reference ellipsoid; combined with elevation factor it converts ground distances to grid distances.

The conversion of measured ground distances to grid distances by applying combined scale and elevation factors, required before grid coordinates can be computed from field measurements.

A mathematically defined oblate spheroid that approximates the shape of the Earth, used as the reference surface for geodetic coordinates and map projections.

The equipotential surface of the Earth's gravity field that approximates mean sea level; heights above it are orthometric elevations, and the geoid differs from the ellipsoid.

A reference surface for measuring elevations, historically based on mean sea level at tide stations, now often realized through gravity-based geoid models such as NAVD88.

A permanent monument of known elevation or position used as a reference for vertical or horizontal control surveys and construction work.

A survey establishing precise horizontal and vertical positions of a network of points that supports subsequent boundary, topographic, and construction surveys.

A method of determining elevation differences by reading a graduated rod through a level instrument from setups between points, carrying height forward through turning points.

Rod readings taken on a known point (backsight) and on a new point (foresight); the difference gives the elevation change between them in differential leveling.

A temporary point on which a foresight and a subsequent backsight are taken, allowing the level instrument to be moved while elevation is carried forward.

An electronic instrument combining an angle-measuring theodolite with an electronic distance meter and onboard computer, used to measure angles and distances to targets.

A correction applied to electronic distance measurements to account for the difference between the reflector's effective optical center and its mounting point, often added to slope distances.

An adjustment to electronic distance measurements accounting for air temperature and pressure differing from the instrument's reference conditions, which changes the speed of light.

Global Navigation Satellite System, such as GPS, providing position by measuring signal travel times from satellites; survey-grade use requires careful observation and correction methods.

Real-Time Kinematic positioning, a GNSS technique using carrier-phase measurements and a correction link from a base station to deliver centimeter-level positions in the field.

A boundary description system that defines a parcel by a sequence of courses and distances, typically beginning at a known point and returning to close the boundary.

A physical object such as a pipe, iron pin, or stone set or accepted to mark a boundary corner or survey point, often controlling over recorded distances.

Physical or documentary indications of an original boundary corner, such as monuments, bearing trees, or record references, used to reestablish the corner's position.

A survey that follows and reestablishes the lines and corners of an existing parcel or subdivision as originally created, rather than creating new boundaries.

A legal doctrine under which a person may acquire title to land through open, notorious, exclusive, hostile, and continuous possession for a statutory period.

A right held by one party to use another's land for a specific purpose, such as access or utilities, without owning the land; it can burden a parcel's use and value.

A map of a land subdivision or survey showing boundaries, lots, streets, and monuments, typically recorded with a government office and used as a legal description.

A survey that locates natural and constructed features and determines elevations, producing a map with contour lines and spot elevations for design and planning.

A line on a map connecting points of equal elevation; the spacing and shape of contours show slope steepness and terrain form.

A computer representation of ground surface elevations, often built from survey points or breaklines, used to generate contours, volumes, and design surfaces.