Leica TS13 User Manual page 76

Reduction to mean
sea level DD
2
Projection distortion
DD
3
Atmospheric
corrections °C
76
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 avail-
able. 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.
Atmospheric corrections in ppm with temperature [°C], air pressure [mb] and
height [m] at 60% relative humidity.
550 mb 600 650 700
50°C
40°C
30°C
20°C
10°C
0°C
-10°C
-20°C
550 mb 600 650 700
5000 m 4500 4000 3500 3000
TS_108
DD
Reduction to mean sea level [ppm]
2
H Height of EDM above sea level [m]
R
6.378 * 10
DD
Projection distortion [ppm]
3
X Easting, distance from projection
zero line with the scale factor 1
[km]
R
6.378 * 10
750 800 850 900 950
750 800 850 900 950
2500 2000 1500 1000 500
6
m
6
m
1000 1050 mb
50°C
40°C
30°C
20°C
10°C
0°C
-10°C
-20°C
1000 1050 mb
0 m
Technical Data