Spectra Precision Survey Pro v4.6 Ranger User Manual User Manual

Page 275

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GPS Module

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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.

Mapping Plane Mode:
Scale
: is the scale difference between the intermediate mapping

plane using the autonomous GPS position and the actual mapping
plane control coordinates. Scale should be very close to 1.0. A value of

1.0 corresponds to grid distances on the selected conformal mapping
plane.
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 scale bias in the

control point plane coordinates, which you may want to correct by

solving a fixed scale transformation.

Rotation: is the rotation between intermediate mapping plane using

the autonomous GPS position and the actual mapping plane. The

rotation should be very close to 0.0. A rotation value significantly
greater or smaller than 0.0 may indicate problems with the control

point accuracy and/or control measurement precision. It might also be
an orientation bias of the mapping plane control system that you wish

to solve for.
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. This value represents

the shift introduced by the inaccurate autonomous GPS starting
position, and is usually less than 10m, the accuracy of an autonomous

GPS position.

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