Spectra Precision Survey Pro v4.6 Recon and Nomad User Manual - Manual (Page 298)

User’s Manual – GPS Mode
288
Localization Parameters Explained
Before you accept a localization solution, you should evaluate the
parameters and the quality of the solution. This section describes the
meaning and the expected values for the six horizontal and five
vertical localization parameters. Guidelines for the quality and
geometry of control points plus the solution redundancy and residuals
are also described.
Horizontal
Ground - TDS Localization Mode:
Scale: is the scale difference between the intermediate mapping
plane and the local system. Scale should be very close to 1.0. A value
of 1.0 corresponds to ground level distances at the base reference
height.
Scale values are often reduced to parts per million in order to relate
the factor to a distance. One ppm (the sixth decimal place i.e.
1.000001 or 0.999999) is equal to 1mm in 1km. This is well below
RTK precision. Fifteen ppm (1.000015 or 0.0.999985) is equal to
15mm in 1km. This is a usual RTK precision, so anything in this
range is expected. A scale value significantly greater or smaller than
1.0 may indicate problems with the control point accuracy and/or the
control measurement precision. It might also indicate a base
reference height too high or low for the survey area, or a scale bias in
the control point local coordinates.
Rotation: is the rotation between the localization map projection
zone and the local system. The rotation represents the difference
between grid north and geodetic north at the meridian passing
through the origin of the localization transformation. Because most
local coordinate systems are not referenced to a geodetic azimuth, any
number could be a valid parameter here.
Origin: is the coordinate on the intermediate mapping plane of the
centroid of the control points. It is calculated by average of the
mapping plane (y,x) coordinates of all control points.
Translation: is the shift from the Origin to the centroid of the
control points in the local coordinate system.