Leica Viva TS16 User Manual page 87

Formulas
Reduction to mean
sea level DD
2
Projection distortion
DD
3
Technical Data
The index n is calculated from the formula of the IAG Resolutions (1999), and
is valid for:
Air pressure p:
Air temperature t:
Relative air humidity h:
Formula for visible red laser
0.29535 · p
ΔD
= 286.338 -
1
002419_002
Atmospheric correction [ppm]
DD
1
p Air pressure [mbar]
t Air temperature [°C]
h Relative humidity [%]
a
1
273.15
x (7.5 * t/(237.3 + t)) + 0.7857
If the basic value of 60 % relative humidity as used by the EDM is retained, the
maximum possible error in the calculated atmospheric correction is 2 ppm,
2 mm/km.
The values for DD are always negative and are derived from the following for-
2
mula:
H
ΔD
6
= -
· 10
2
R
TS_106
The magnitude of the projection distortion is in accordance with the projection
system used in a particular country, for which official tables are generally
available. The following formula is valid for cylindrical projections such as that
of Gauss-Krüger:
2
X
ΔD 6
=
· 10
3
2
2R
TS_107
In countries where the scale factor is not unity, this formula cannot be directly
applied.
1013.25 mbar
12 °C
60%
-4
4.126 · 10 · h
x
-
· 10
Reduction to mean sea level [ppm]
DD
2
H Height of EDM above sea level [m]
R
6.378 * 10
Projection distortion [ppm]
DD
3
X Easting, distance from projection
zero line with the scale factor 1
[km]
R
6.378 * 10
6
m
6
m
87