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13 APPENDIX
13-5
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)
Corrected vertical distance (V)
● Calculation formula when atmospheric refraction and earth curvature
correction parameter is set to “OFF”:
S: Slope distance
α: Vertical angle from horizontal
K: Atmospheric refraction coefficient (0.14 or 0.2)
Re:Diameter of earth (6,370 km)
Horizontal distance H' = S · Cosα
Vertical distance V' = S · Sinα
V= S (Sinα + Cosα ·
1–K
· S · Cosα)
2Re
H= S (Cosα + Sinα ·
K–2
· S · Cosα)
2Re
PENTAX R-300 (p65-88) 10/30/02 11:11 AM Page 83