S+SNZ Geodetic Survey key terms

A survey that defines, marks, or re-establishes the boundaries of a parcel of land for registration purposes, tying the boundary to the national geodetic datum and to statutory survey rules.

A defined area of land with a unique legal identifier, held under a single title or interest, whose spatial extent is recorded in the cadastre and on the survey plan.

The official register of land parcels that records their spatial extent, unique identifiers, and legal interests, maintained as a public record and usually linked to the land titles system.

The process of re-establishing an existing legal boundary on the ground from survey records and physical evidence, resolving conflicts between the two before placing new marks.

A durable physical mark, such as a steel pin, peg, or concrete block, placed or adopted at a survey corner to evidence the position of a boundary point on the ground.

A reference mark placed near a corner or boundary point, often offset and recorded by bearing and distance, so the corner can be relocated if the primary mark is disturbed or destroyed.

The system of rights, obligations, and restrictions under which land is held, including freehold, leasehold, and customary interests, which determines what a cadastral survey must define.

A legal right to use another person's land for a specific limited purpose, such as access, drainage, or services, recorded as a spatial interest over the burdened parcel.

Acquisition of title to land by long, open, continuous occupation without the owner's permission, subject to statutory time limits and often excluded for registered land.

The reference surface and coordinate system, together with its defining parameters, to which survey measurements and boundary positions are referred for legal and technical purposes.

A mathematically defined reference for horizontal or vertical positions, comprising an ellipsoid, an origin, and the parameters that relate the ellipsoid to the Earth's physical shape.

The equipotential surface of the Earth's gravity field that best approximates mean sea level, used as the reference for orthometric heights and for relating GNSS heights to level heights.

A smooth mathematical surface of revolution used to approximate the Earth for coordinate computation, defined by a semi-major axis and flattening, and distinct from the physical terrain.

The height of a point above the geoid, measured along the plumb line, representing height above mean sea level rather than height above the ellipsoid.

A grid or mathematical representation of the separation between the geoid and a reference ellipsoid, used to convert GNSS-derived ellipsoidal heights into orthometric heights.

Global Navigation Satellite System, a family of satellite positioning systems such as GPS, GLONASS, Galileo, and BeiDou that provide position and time by ranging to satellites.

Real-Time Kinematic positioning, a GNSS technique that resolves carrier-phase ambiguities using corrections from a base station or network to deliver centimetre-level positions in real time.

Continuously Operating Reference Station, a permanently installed GNSS receiver that streams observation data or corrections to support network positioning and datum realisation.

A set of coordinated survey points of known position and quality, established in a hierarchy and used to connect, check, and constrain subsequent surveys and measurements.

A survey method in which a series of connected lines between stations is measured by distance and angle, and coordinates are computed and checked for misclosure around the figure.

The difference between a measured quantity and its known or geometrically required value, such as the gap in a closed traverse, used to assess and distribute survey error.

A statistical method that estimates unknown coordinates or parameters by minimising the sum of squared weighted residuals, providing the most probable solution and a measure of precision.

The difference between an observed value and the value predicted by the adjusted model, used to detect outliers, assess observation quality, and describe the fit of the adjustment.

A graphical representation of positional uncertainty at a point, showing the magnitude and orientation of the semi-major and semi-minor standard errors from a covariance matrix.

An electronic instrument combining a theodolite with an electronic distance meter, used to measure horizontal and vertical angles and slope distances to targets and compute coordinates.

A survey technique for determining height differences, commonly by reading a graduated staff with a level instrument along a line of sight, or by trigonometric or GNSS methods.

A measurement of the speed of sound through the water column with depth, used to correct acoustic depths for refraction and to compute accurate reduced depths.

A hydrographic sonar that transmits a fan of acoustic beams across the vessel track to measure depth and produce dense swath coverage of the seabed.

The low-water reference surface to which depths and drying heights on a nautical chart are reduced, chosen so that the tide seldom falls below it.

A height or depth expressed relative to a stated reference surface, after correction for instrument, tide, sound velocity, and other systematic effects in the survey.

A reference level derived from analysis of tide observations, such as lowest astronomical tide or mean high water, used as the zero for heights and depths in a defined area.

The process of transferring designed positions, levels, and alignments from plans onto the ground by survey methods so that construction can proceed to the specified geometry and tolerance.

A survey of completed or partially completed works that records actual positions and levels, used to verify compliance with design and to update record information.

A specified height or grade shown on engineering drawings that a constructed surface or structure must achieve, referenced to a stated datum and checked during setting out.

The longitudinal profile of a road or pipeline defined by grades and vertical curves, controlling crest and sag geometry and drainage for the constructed facility.

The plan geometry of a road or corridor, comprising straights, circular curves, and transition spirals, which determines the horizontal position of the centreline for setting out.

The division of a parcel of land into two or more new lots or allotments, typically requiring a survey plan, statutory approval, and provision of access and services.

The shaping of the physical form, layout, and public realm of towns and neighbourhoods, integrating buildings, streets, open space, and infrastructure at a scale between planning and architecture.

The process of converting land to a new or more intensive use, including feasibility, planning consent, subdivision, infrastructure, and construction, coordinated with survey information.

A digital, spatially enabled cadastre that models parcels and interests in a geographic information system, supporting query, analysis, and integration with other land information.

Geographic Information System, software and data for capturing, storing, analysing, and displaying information referenced to geographic location, used to manage and query survey and land data.

A mathematical transformation that maps positions on the curved Earth onto a flat plane, introducing distortion in distance, area, or direction that must be understood when using map coordinates.

Descriptive information about data, such as its source, accuracy, datum, currency, and intended use, which enables users to judge whether the data is fit for purpose.