Spectra Precision ProMark 800 Reference Manual - Manual (Page 81)

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Precise Surveying - Field Applications & Concepts
accuracy about 68% of the time. This percentage
corresponds to the 1-sigma width on the Gaussian curve.
2. Some manufacturers use the “2drms” measure, which is
derived from the rms measure on the horizontal plane,
using the following formula:
3. CEP (Circular Error Probable): accuracy is equal to the
circle's radius, centered at the true position, containing
50% of the points in the horizontal scatter plot (see chart
below). This means the computed position will be within
the announced accuracy 50% of the time.
Localization
What is
Localization?
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.
1sigma
68%
1sigma
Accuracy 2drms ( ) 2 Accuracy rms ( ) × =
X0
CEP
Y0