GeoMax Zoom10 - Reduction Formulas

14.7 Reduction Formulas
c
a
b
SD
VD
HD
a Mean Sea Level
b Instrument
c Reflector
SD Slope distance
HD Horizontal distance
VD Height difference
The instrument calculates the slope distance, horizontal distance, and height difference in
accordance with the following formulas. Earth curvature (1/R) and mean refraction coefficient (k
= 0.13) are automatically taken into account when calculating the horizontal distance and height
difference. The calculated horizontal distance relates to the station height and not to the reflec-
tor height.
Slope distance
SD
= D
0
· ( 1 + ppm · 10
-6
) + p
SD Displayed slope distance [m]
D0 Uncorrected distance [m]
ppm Atmospheric scale correction [mm/km]
p prism constant [m]
Horizontal distance
HD
= Y - A · X ·
Y
HD Horizontal distance [m]
Y SD * |sinζ|
X SD * cosζ
A
(1 - k/2)/R = 1.47 * 10
-7
[m
-1
]
ζ = Vertical circle reading
k = 0.13 (mean refraction coefficient)
R = 6.378 * 10
6
m (radius of the earth)
Height difference
VD
= X + B · Y
2
VD Height difference [m]
Y SD * |sinζ|
Formulas
Technical Data 99