• Atmospheric correction.
• Reduction to mean sea level.
• Projection distortion.
Atmospheric correction D1: The slope distance displayed is correct if the scale correction in ppm, mm/km, which has been entered corresponds to the atmospheric conditions prevailing at the time of the measurement.
The atmospheric correction includes:
• Adjustments for air pressure
• Air temperature
• Relative humidity
For highest precision distance measurements, the atmospheric correction
should be determined with an accuracy of 1 ppm. The following parameters
must be redetermined:
• Air temperature to 1 °C
• Air pressure to 3 mbar
• Relative humidity to 20%
Air humidity
The air humidity influences the distance measurement if the climate is
extremely hot and damp. For high precision measurements, the relative humidity must be measured and entered along with the air pressure and the temperature.
Air humidity correction
Index n
Formulas
Reduction to mean sea level D2
Projection distortion D3
Atmospheric corrections °C
Atmospheric corrections °F
