DC Land Surveyor Exam key terms

The physical object, such as a pipe, pin, or stone, that was set and described in a recorded survey or deed, and whose position governs the boundary it marks even if it disagrees with the written distances.

The ordered hierarchy courts and surveyors apply when boundary evidence conflicts, generally prefering natural monuments, then artificial monuments, then courses and distances, then area, with intent controlling over strict measurement.

Boundary or use interests created without a recorded document, including prescriptive easements, boundary by acquiescence, and practical location, which can override the paper deed location of a line.

A statutory doctrine by which a person who openly, actually, exclusively, hostilely, and continuously occupies another's land for the required period may gain title, measured against the record owner's cause of action.

A written instrument that appears to convey title but is legally defective, such as a deed from a grantor with no interest; it can support constructive adverse possession and extend the claimed area to the instrument's boundaries.

A property line bounded by a non-tidal watercourse, which typically shifts with gradual accretion or reliction but stays fixed under avulsion, and follows the thread or ordinary high water mark depending on state law.

The gradual and imperceptible addition of land by water action, such as sediment deposition along a stream bank, which belongs to the riparian owner without any deed or payment.

A sudden, perceptible change in a watercourse channel, such as a flood cutting a new course, which does not move property boundaries; the old channel remains the legal line unless statute provides otherwise.

A survey line run along a water body to compute area and identify the general shore, not a boundary of the upland title; the actual water boundary controls unless the meander was intended as the true line.

The equipotential surface of Earth's gravity field that approximates mean sea level, extended through the continents; it is the reference surface for orthometric heights and is irregular relative to an ellipsoid.

The separation, usually denoted N, between the reference ellipsoid and the geoid at a point, so that ellipsoidal height equals orthometric height plus N; modern GNSS workflows use a geoid model to derive elevations.

A point's height above the geoid, measured along the plumb line and commonly called elevation; it differs from GNSS ellipsoidal height by the geoid undulation and is the value used in drainage and construction design.

A system of conformal map projections established per state so that grid coordinates can be used for surveying and mapping, with zones designed to limit scale distortion and defined on a published datum.

The difference between distances, angles, or areas measured on the curved Earth and their representation on a flat grid, quantified by scale factor and elevation factor and corrected when converting between grid and ground values.

The process of converting projected grid distances to horizontal ground distances by dividing by the combined scale factor, or the reverse, so that surveyed measurements match coordinates on a map projection.

The product of the projection scale factor at a point and the elevation factor, used to relate grid distance to ground distance; multiplying a ground distance by it gives the grid distance.

A reference surface and set of constants from which elevations are measured, such as the North American Vertical Datum of 1988, realized through a network of benchmarks and periodically updated by national agencies.

A stable, identifiable point with a known elevation or position, often a monumented disk or a published control station, used as a starting reference for leveling and construction vertical control.

The computed misclosure between a traverse's starting and ending known values, expressed as linear error, angular error, or a ratio such as 1:10,000, used to judge whether the survey meets accuracy standards.

A statistical method that distributes random errors among redundant observations by minimizing the sum of squared residuals, yielding adjusted coordinates and estimated precisions for each unknown.

The difference between an observed value and its adjusted or computed value after adjustment; residuals reveal error patterns and, with weights, drive the least squares solution.

A gross, non-random mistake such as a misread rod, wrong point number, or transposed digit; unlike random error it cannot be averaged out and must be detected and removed before adjustment.

An electronic instrument combining an electronic theodolite with an electronic distance meter and onboard computer, measuring horizontal and vertical angles plus slope distance to compute coordinates and elevations of observed points.

The offset between the physical center of a retroreflector and the point to which its stated constant refers, entered into the instrument so measured distances are corrected to the prism center or plumb line.

A correction applied to electronic distance measurements for air temperature, pressure, and humidity, because the speed of light in air varies from the instrument's reference conditions and changes the measured range.

Distance measurement using a laser returned from a target surface without a prism; accuracy depends on surface reflectivity and incidence angle, and the beam width can cause errors on edges or foliage.

A GNSS technique in which a base station or network sends corrections to a rover, resolving carrier-phase ambiguities so positions accurate to centimeters are available in the field in real time.

A GNSS positioning method using corrections modeled from a network of continuously operating reference stations, providing a virtual reference station or area correction to rovers over a wide region.

A permanently installed, continuously tracking GNSS receiver whose data are archived and distributed, often for post-processing, network corrections, and maintaining a national spatial reference frame.

Position dilution of precision, a unitless measure of how satellite geometry amplifies ranging error; lower values indicate stronger geometry, and high values warn of poor positioning conditions.

A map of a subdivision or land partition prepared for recording, showing lots, blocks, streets, easements, and dedications, and required by local subdivision regulations before lots may be conveyed.

Local ordinances governing how land is divided, including plat content, review and approval procedures, improvement standards, and dedications, which must be satisfied before a plat is recorded.

The intentional conveyance of private land to public use, such as streets or parks shown on a plat, which typically requires acceptance by the governing body to become effective.

A nonpossessory right to use another's land for a specific purpose, such as utilities or access, which burdens the servient parcel and may be shown on plats and described in deeds.

A detailed survey of real property prepared to a national standard for title insurance and lending purposes, depicting boundaries, improvements, easements, and specified optional table items.

A survey performed after construction to document the actual location of improvements, utilities, and grades relative to design, often required before acceptance or occupancy.

Earthwork in which soil is removed (cut) from high areas and placed (fill) in low areas to reach design grades; volumes are computed from cross sections or digital terrain models.

The ethical duty to undertake only work for which one is qualified by education and experience, or to associate with someone who is, and to keep skills current through continuing education.

The degree of care, skill, and diligence that a reasonably prudent surveyor would exercise under similar circumstances, used to judge negligence in professional liability claims.

A situation in which a surveyor's personal, financial, or other interest could bias professional judgment, which must be disclosed and avoided or managed to preserve objectivity and client trust.

A system for capturing, storing, analyzing, and displaying spatially referenced data, linking geometry to attribute tables and supporting overlay, network, and proximity analysis for land records and planning.

Documentation describing spatial data, including source, accuracy, projection, currency, and responsible party, which lets users judge whether a dataset suits a particular purpose.

A raster or triangulated representation of ground surface elevation, used for contours, drainage analysis, visibility, and earthwork volumes; its accuracy depends on source data and resolution.

Light detection and ranging, an active remote sensing method that fires laser pulses and times their return to produce dense point clouds of terrain, vegetation, and structures for mapping and elevation models.

The measurement of water body depths and bottom features, referenced to a stated vertical datum, to produce charts and models used for navigation, dredging, and engineering design.

A depth measurement below a reference surface, corrected for instrument draft, water level, and sound velocity; soundings are reduced to chart datum for navigation charts.

A reference elevation derived from tidal observations, such as mean lower low water or mean high water, used as the zero for charted depths and for defining coastal boundaries.