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When determining height differences by using trigonometric levelling method, some affecting values are present. Besides measuring imperfection due to instrumental imperfection and surveyorпїЅs errors, quality of the trigonometric levelling results also depends on following external affecting values: height difference between observed points, distance between observed points and temperature gradient (change of temperature with height) between observed points. Therefore, if the height difference is bigger, the influ...

The determination of heights using the me thod of geometric levelling belongs to the most precise geodetic measurements. The majo rity of errors in geometric levelling can be eliminated in the most part by testing and rectification of instruments, by selecting an appropriate measuring method and the most convenient external conditions and the time of the day and the year. The errors that canno t be eliminated in f iled conditions are the error of staff scale, the error of irregula rly attached staff scale and the ...