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Localization
What is
Localization?
distributed across the surface of the geoid. For each point,
the file provides the horizontal geographic coordinates and
the separation (geoidal separation) between the reference
ellipsoid and the geoid. The extent of the geoid file may be
worldwide or limited to a particular area.
Providing an accurate modelling of the undulations of the
geoid surface, the geoid file is used by the GNSS system to
interpolate the separation between this surface and the
surface of the reference ellipsoid for the point surveyed.
Geoid
[1]: Elevation (above geoid)
[2]: Interpolated geoidal separation
From this interpolation the system can derive elevation from
ellipsoidal height using the following formula:
Elevation [1] = Ellipsoidal Height - Interpolated geoidal separation
Localization, also known as "calibration" or "determining the
local grid", consists of accurately determining a local grid
that fits in with the job you want to perform. The localization
process performs a rotation and translation of the plane
defined by the projection system chosen for the job.
After localization has been run, your equipment provides the
coordinates of every point, including new surveyed points, on
this local grid.
Typically through localization, your equipment determines
the new local grid (a plane) by comparing the known local
coordinates of one or more reference points with the
corresponding geographic coordinates entered or measured
for these points.
Precise Surveying - Field Applications & Concepts
Surveyed Point
[1]
[2]
To center of ellipsoid
Reference
Ellipsoid
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