Spectra Precision Survey Pro v5.4 - Manual (Page 44)

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Leveling Mode -
Getting Ready for
Leveling
Leveling can be performed using one of two techniques:
• Automatic leveling: An automatic level is used to take readings on a
graduated level rod. This is the traditional leveling technique for surveying.
It can be performed by manually reading the rod, or by using a digital
automatic level such as the DiNi to electronically read the rod.
• Trigonometric leveling: An optical total station is used to measure zenith
angle and slope distance to a prism on a pole. This alternative leveling can
be performed with a total station and a prism on a fixed height pole.
Depending on the technique you wish to use, you must configure your
instrument and possibly select a leveling method.
Auto/Manual Leveling Methods
Survey Pro supports the following leveling methods:
• Three Wire: An automatic level is used and the operator observes the
leveling rod at the upper, middle, and lower wire of the level stadia. This
method is used with the “Manual Mode” instrument profile.
• Single Wire: Same as three-wire leveling, except that only the middle wire
is read and entered using the “Manual Mode” instrument profile.
• Electronic: An electronic automatic level is used to digitally observe a bar-
coded level rod. This method is used with one of the supported electronic
level instrument profiles.
• Trigonometric: An optical total station is used to observe a prism on a prism
pole to measure vertical distance. This method is used with any electronic
total station instrument profile. It can also be used with the “Manual
Mode” instrument profile if you wish to hand enter zenith and slope
distance observations from a field book.
NOTE: Trigonometric leveling (trig leveling) is a different survey technique than
performing a 3D optical survey with a total station.
In trig leveling, you do not set up the optical total station on a known point, and you
do not measure the height of the instrument or the height of the rod at any time
during the survey.
Trig leveling is more like traditional leveling in that you set up the instrument in
between the points in each turn, you observe the rod at the backsight to establish
the height of the instrument, then you observe the rod at the foresight to establish
the foresight elevation. Because the foresight observation is subtracted from the
backsight observation, the height of the rod, which must be kept constant between
the backsight and foresight of each turn, cancels out. Therefore, in trig leveling, you
never need to enter the height of the rod. The height of the instrument above the
ground at each location is also not used in this procedure.