CA Surveying key terms

A physical object such as an iron pipe, brass cap, or concrete post placed or accepted to mark a property corner or boundary line, serving as physical evidence of a boundary location.

A method of describing land by following directions and distances, often along physical features, from a defined point of beginning around the parcel until the description closes back on that point.

A map filed with the county surveyor under California law when a licensed surveyor sets corners, finds conflicting evidence, or performs certain boundary surveys, showing monumentation, measurements, and the survey procedures used.

A right held by one party to use another person's land for a specific limited purpose, such as access, utilities, or drainage, without owning the underlying fee title to that land.

A doctrine allowing a person to gain title to another's land through possession that is open, notorious, hostile, exclusive, and continuous for the statutory period, generally five years with tax payment in California.

The principle that when two deeds, patents, or descriptions conflict, the conveyance with the earlier effective date generally prevails over the later one to the extent of the overlap.

A fractional division of a U.S. Public Land Survey section created by repeated halving, such as a half-section, quarter-section, or quarter-quarter-section, normally containing 320, 160, or 40 acres respectively.

A method of restoring lost Public Land Survey subdivision corners by dividing the record distances of section lines in proportion to the difference between the record and measured total distances.

A doctrine under which adjoining owners may fix an uncertain or disputed boundary by mutual agreement and later acquiescence, making the agreed line binding on them and on their successors.

The chronological sequence of recorded documents, including deeds, patents, liens, and easements, that traces ownership of a parcel from its original grant to the present owner.

A boundary along a watercourse or lake that can shift gradually with accretion or erosion, but generally remains fixed where the water changes course suddenly by avulsion.

A durable, identified point of known elevation, often tied to a geodetic datum, used as a reference for leveling and for vertical control in surveying and construction work.

Earthwork operations in which soil is excavated from high ground and placed in low areas to bring a site to design grade, ideally with balanced volumes on the project.

A point on a survey baseline or alignment expressed as a distance from a starting point, commonly in 100-foot units where station 1+00 equals 100 feet.

The central angle subtended by a 100-foot arc (arc definition) or a 100-foot chord (chord definition) of a circular highway curve, expressing the sharpness of the curve and its radius.

A parabolic curve joining two intersecting grade lines on a roadway or pipeline to provide a gradual change in slope, defined by its length, tangent grades, and K value.

A marker set at the catch point where the design slope meets existing ground, showing the amount of cut or fill and the offset distance so grading crews know where to work.

A survey performed after construction that records the actual location, elevation, and dimensions of improvements, used to verify compliance with design and to update record drawings.

A procedure that determines elevation differences by reading a graduated rod at successive instrument setups, using backsights, foresights, and turning points between points of known elevation.

The longitudinal slope of a surface such as a road, pipe, or drainage channel, usually expressed as a percentage of rise over run or as a ratio.

A reference framework that defines positions on the Earth, including a reference ellipsoid and an origin; the North American Datum of 1983 is the horizontal datum used in California.

A mathematically defined surface formed by rotating an ellipse about its minor axis, used to approximate the size and shape of the Earth for geodetic computations and coordinate systems.

The equipotential surface of the Earth's gravity field that best matches mean sea level; it serves as the reference surface for orthometric, or mean sea level, heights.

A system of planar coordinates defined for each state on a conformal map projection; California has six zones, all based on the Lambert conformal conic projection.

The product of a grid scale factor and an elevation factor, used to convert between horizontal ground distances measured in the field and distances on a projected coordinate grid.

A survey in which a connected series of courses with measured directions and distances is used to establish new positions or to extend horizontal control across an area.

A horizontal direction measured clockwise from a chosen reference meridian, usually true or grid north, running from 0 through 360 degrees around the horizon.

A direction expressed as an acute angle east or west of north or south, such as N 45 degrees E, rather than as a continuous angle measured around the full horizon.

The angle between magnetic north and true geographic north at a given place and time; it must be applied to convert magnetic bearings into true directions.

Real-time kinematic surveying in which a GPS or GNSS rover receives corrections from a known base station or network, producing centimeter-level positions while working in the field.

The amount by which a traverse or level loop fails to return to its starting value, computed as error in latitude and departure or in elevation and compared with allowable tolerance.

The constant vertical distance between adjacent contour lines on a topographic map, chosen to suit the map scale and the relief of the terrain being mapped.

A raster dataset of terrain elevations at regularly spaced grid points, used for terrain analysis, volume computations, and generation of contours or shaded relief.

Light detection and ranging: a remote sensing method that fires laser pulses and measures return times to build dense, accurate three-dimensional point clouds of terrain and surface features.

Aerial imagery geometrically corrected for camera tilt, terrain relief, and lens distortion so that it has a uniform scale and can serve as a map base.

The science of deriving measurements and three-dimensional positions of objects from overlapping photographs or other imagery, widely used for topographic mapping and large-area mapping.

A computer system for storing, managing, analyzing, and displaying spatially referenced data as layers of features and attributes tied to locations on the Earth.

A surveyed point of known coordinates or elevation, often marked with a photo-identifiable target, used to orient, scale, and check aerial, photogrammetric, or LiDAR mapping data.

How close a measured or computed value is to the true or accepted value; systematic errors degrade accuracy and are often detected by comparison with higher-order control.

The degree of consistency or repeatability among repeated measurements of the same quantity, independent of how close those measurements happen to be to the true value.