Cogo Calculation - Shift, Rotate & Scale (Match Pts) Method - Leica GPS1200 Series Technical Reference Manual

COGO
37.10
Description
Computation of shift,
rotation and scale
values
COGO Calculation - Shift, Rotate & Scale (Match Pts) Method
The COGO calculation shift, rotate & scale (match pts) applies shifts and/or rotation and/or
scale to one or several known points. The shifts and/or rotation and/or scale are calculated
from selected points using a 2D Helmert tranformation.
Elements that must be known are
• the coordinates of at least two matching points for the calculation of the shifts and/or rota-
tion and/or scale.
• the coordinates of the points to be shifted, rotated and/or scaled. They must be stored in
the active job.
• the shift values. They can be defined as the direction of Easting, Northing and Height or
as an azimuth and a grid distance or as shift from one point to another.
• the rotation value. It can be defined by a point as rotation center plus a rotation or by an
existing and new azimuth.
• the scale. It is only applied to the position.
Points with full coordinate triplets, position only points and height only points can be used.
The number of pairs of points matched determines whether the shift, rotation and scale
values are computed.
Number of pairs of Shift East
points matched
1 x
> 1 x
GPS1200
Shift North
x
x
Shift Height Rotation
x -
x x
882
Scale
-
x