Multipath (Multipath Error): The error that results when a reflected GNSS signal is received. Includes any data that is used as basemap data in planning and design, any data in which contours are generated, any data that is used for survey and design purposes, and any imagery where point clouds are derived and used for planning and design, including the generation of models, in which the surface of the ground is being modeled. Mapping Survey: The collection of points to define a physical surface’s features (natural, manufactured, or both). LiDAR (Light Detection and Ranging): A remote sensing method that uses light as a pulsed laser to measure variable distances to the Earth’s surface. Examples may include Aerial Mapping Surveys, Mobile Mapping Surveys, UAS-based photogrammetry, etc. The INS-based mapping survey collection equipment relies on positioning based on INS solutions and/or mapping control points. INS-Based Mapping Surveys: The collection of points to define the features (natural, manufactured, or both) of a physical surface that is carried out without the direct observation of geodetic/primary control points. These systems are often paired with cameras and LiDAR (Light Detection and Ranging) for mapping surveys. Internal Navigation System (INS): A collection of sensors (typically a GNSS receiver and Internal Measurement Unit (IMU) or some combination thereof) that provide the positional information of a data collecting device (position and attitude) without direct observation of project control. Hydrographic Survey: A survey having for its principal purpose the determination of data relating to bodies of water, and which may consist of the determination of one or several of the following classes of data depth of water and configuration of bottom directions and force of current heights, times and water stages and location of fixed objects for survey and navigation purposes. The European Space Agency system is known as GALILEO. The Russian system is known as the Global'naya Navigatsionnaya Sputnikovaya Sistema or GLONASS. The US system is known as NAVSTAR Global Positioning System (GPS). Global Navigation Satellite System (GNSS): Any satellite system which can be used to determine a precise location on the surface of the Earth. “The datum, as defined in (1), together with the coordinate system and the set of all points and lines whose coordinates, lengths, and directions have been determined by measurement or calculation.”.“A set of constants specifying the coordinate system used for geodetic control, i.e., for calculating the coordinates of points on the Earth.”.The number of areas and the DTM accuracy class for each area is set by the District Survey Operations Manager.ĭz: Mathematical difference between elevations of check points and elevations produced from the TIN (created from the Survey Points) at the exact horizontal location.ĭifferential Leveling: Determining the difference in elevation between two points by the sum of incremental vertical displacements of a graduated rod.Įlevation Scale Factor: A multiplier used to change horizontal ground distances to geodetic (ellipsoid) distances. (Vegetation and other objects/artifacts are removed digitally from the surface)ĭTM Accuracy Class: A specific area within the mapping limits with an assigned maximum allowable Dz and RMSE. Check points are used to verify the accuracy of the TIN.Ĭombined Scale Factor: A conversion factor that uses the combination of the Grid Scale factor and the Elevation Scale Factor of a point to reduce horizontal ground distances to grid distances.Ĭonventional Mapping Survey: A Conventional mapping survey is the collection of points to define the features (natural, manufactured, or both) of a physical surface that is collected directly from ground control, using conventional survey equipment, and is physically measured using a total station, Terrestrial Scanner, or GNSS equipment.ĭepartment: The Department of Transportation, State of Ohio.ĭigital Terrain Model (DTM): A bare earth model of the earth that can be used in CADD programs. Janu| Agency Published: JanuGlossary of Terms View TermsĪzimuth Mark: A Type ‘A’ or Type ‘B’ project control monument set at the end points of the project for use as a ‘backsight’ point.īenchmark: A relatively permanent object, natural or artificial, bearing a marked point whose elevation is above or below a referenced datum with a known published elevation.Ĭheck points: 3-dimensional positions obtained independently of survey points by traditional ground surveying, Real Time Kinematic GNSS surveying or Static GNSS.
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