Atmospheric Refraction And Earth Curvature Correction - Pentax R-422VN Instruction Manual

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12.5 Atmospheric refraction and earth curvature correction

• Atmospheric refraction and earth curvature correction refers to correcting both the bending
of the light beam caused by atmospheric refraction and the effect on the height differential
and horizontal distance caused by the earth curvature.
• Correction called "atmospheric refraction and earth curvature correction" is initiated to
correct error when the slope distance and vertical angle are caused to determine the
horizontal distance and the height differential. With this instrument, the following formula
is used to correct these factors.
• Calculation formula when atmospheric refraction and earth curvature correction parameter
is set to "ON":
Corrected horizontal distance (H)
H = S ( cos
Corrected vertical distance (V)
V = S ( sin
• Calculation formula when atmospheric refraction and earth curvature correction parameter
is set to "OFF":
Horizontal distance H' = S
Vertical distance
S: Slope distance
: Vertical angle from horizontal
K: Atmospheric refraction coefficient (0.14 or 0.2)
Re: Diameter of earth (6,370 km)
62
9.0 4.9 3.2
K-2
+ sin 2Re S
2Re
1-K
+ cos 2Re S
2Re
cos
V' = S sin
Re=6378137
m
0.8 -3.3
cos )
cos )
V'
S
V
H
'
H
-7.4 -11.5