terminology
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terminology [2018/10/09 17:12] – allchin09 | terminology [2018/10/09 17:29] (current) – allchin09 | ||
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|Coordinate transformation| Change of coordinates from one CRS to another, where the CRSs datums differ| | |Coordinate transformation| Change of coordinates from one CRS to another, where the CRSs datums differ| | ||
|Datum| Defines the position of the origin, the scale and the orientation of the axis of a coordinate system with respect to an object| | |Datum| Defines the position of the origin, the scale and the orientation of the axis of a coordinate system with respect to an object| | ||
- | |Easting| Distance in a CRS eastwards | + | |Easting| Distance in a CRS eastwards from a north-south reference |
|Ellipsoid| A closed surface formed by the rotation of an ellipse about a main axis. The figure of the Earth is usually modelled as an ellipsoid which is slightly squished from the shape of a sphere at the poles. Shape usually described by terms //a// and //b// (semi-major and semi-minor axis lengths) or //a// and // | |Ellipsoid| A closed surface formed by the rotation of an ellipse about a main axis. The figure of the Earth is usually modelled as an ellipsoid which is slightly squished from the shape of a sphere at the poles. Shape usually described by terms //a// and //b// (semi-major and semi-minor axis lengths) or //a// and // | ||
|Ellipsoidal height (// | |Ellipsoidal height (// | ||
- | |Geodetic | + | |Geodetic |
|Geodetic latitude| Angle from the equatorial plane to the perpendicular to the ellipsoid through a given point, positive northwards| | |Geodetic latitude| Angle from the equatorial plane to the perpendicular to the ellipsoid through a given point, positive northwards| | ||
|Geodetic longitude| Angle from the prime meridian plane to the meridian plane of a given point, positive eastwards| | |Geodetic longitude| Angle from the prime meridian plane to the meridian plane of a given point, positive eastwards| | ||
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|Gravity-related height (// | |Gravity-related height (// | ||
|Height| Either ellipsoidal or gravity-related height| | |Height| Either ellipsoidal or gravity-related height| | ||
- | + | |Map projection| Coordinate conversion from an ellipsoidal coordinate system to a plane| | |
- | + | |Mean sea level (//MSL//)| Averal level of the surface of the sea over all stages of tide and seasonal variations. Usually defined for a local region from observations of one or more points over a period of time| | |
+ | |Meridian| Intersection of an ellipsoid by a plane containing the shortest axis of the ellipsoid| | ||
+ | |Northing| Distance in a CRS from an east-west reference line, positive northwards| | ||
+ | |Prime meridian| Meridian from which the longitudes of other meridians are quantified| | ||
+ | |Projected CRS| A CRS derived from a 2D geodetic CRS by applying a map projection| | ||
+ | |Vertical CRS| A 1D CRS based on a vertical datum| | ||
+ | |Vertical datum| A datum describing the relation of gravity-related heights or depths to the Earth, usually related to //MSL//. Ellipsoidal heights are instead treated as being related to a 3D ellipsoidal CRS| |
terminology.txt · Last modified: 2018/10/09 17:29 by allchin09