Surveyor's Dictionary
D
Datum
A reference surface or point used as a basis for elevation or position measurements.
Declination
The angle between true north and magnetic north at a given location.
Deed
A legal document describing property boundaries and ownership.
Deflection Angle
The angle between the prolongation of the previous line and the forward line.
Digital Level
An electronic instrument that provides automatic reading of height differences.
Distance
The length or interval between two points or objects.
Diurnal
Daily variations in measurements due to earth's rotation and atmospheric conditions.
Drafting
The process of creating technical drawings from survey data.
Drainage
Natural or artificial removal of surface and subsurface water from an area.
DTM
Digital Terrain Model - a 3D representation of terrain surface.
E
Easement
A right to use another's land for a specific purpose.
Easting
The eastward-measured distance in a coordinate system.
EDM
Electronic Distance Measurement - technology used to measure distances.
Elevation
Height above or below a reference datum.
Encroachment
Unauthorized extension of a structure onto adjacent property.
Endpoint
The terminal point of a survey line or traverse.
Engineering Survey
Survey for design and construction of engineering projects.
Equipment Height
Height of survey instrument above ground point.
Error Analysis
Study of measurement uncertainties and their propagation.
Established Monument
A permanent marker of known position and elevation.
F
Field Book
Notebook for recording survey measurements and notes.
Field Work
Survey activities performed on site.
Fill
Material added to raise ground elevation.
First Order Survey
Highest precision survey classification.
Fixed Point
A survey point with known coordinates.
Foresight
A sight taken on a new point to be established.
Foundation Survey
Survey to establish building foundation location.
Frontage
The width of a property along a street or road.
Full Station
A survey station at 100-foot intervals.
Floodplain Survey
Survey to determine flood-prone areas.
G
Geodesy
Science of earth measurement and mapping.
Geographic Coordinates
Location expressed in latitude and longitude.
Geoid
Earth's theoretical sea-level surface.
GIS
Geographic Information System - system for managing spatial data.
GNSS
Global Navigation Satellite System.
Grade
Slope of a line or surface.
Grid
Network of lines forming squares or rectangles.
Ground Control
Survey points of known position used as reference.
GPS
Global Positioning System - satellite-based positioning system.
Geometric Leveling
Determination of elevation differences using horizontal line of sight.
H
Hand Level
Simple leveling device held in hand.
Height of Instrument
Elevation of telescope axis above datum.
Horizontal Angle
Angle measured in a horizontal plane.
Horizontal Control
Network of points with known horizontal positions.
Horizontal Distance
Distance measured in a horizontal plane.
Hub
Wooden stake used as temporary survey marker.
Highway Survey
Survey for road construction and maintenance.
Hydrographic Survey
Survey of bodies of water and underwater features.
Hypsography
Study and mapping of earth's elevation variations.
Horizontal Curve
Curve in a horizontal plane connecting two lines.
I
IMU
Inertial Measurement Unit - device for measuring orientation.
Index Error
Systematic error in angle measurement.
Indirect Measurement
Measurement computed from other measurements.
Intersection
Method of locating point by observing from two known positions.
Invar
Metal alloy with low thermal expansion used in precise measurement.
Iron Pin
Metal rod used as survey marker.
Isogonic Line
Line of equal magnetic declination.
Instrument Station
Point where survey instrument is set up.
Interior Angle
Angle inside a polygon at a vertex.
Inverse
Calculation of bearing and distance between two points.