How To Used Theodolite/EDM Equipment
Theodolite/EDM Topographic Survey
Description:
Using EDM instruments and optical or electronic theodolites, locate the
positions and elevations of all topographic detail and a sufficient number of
additional elevations to enable a representative contour drawing of the
selected areas. See sample field notes in Figure D.9.
Using EDM instruments and optical or electronic theodolites, locate the
positions and elevations of all topographic detail and a sufficient number of
additional elevations to enable a representative contour drawing of the
selected areas. See sample field notes in Figure D.9.
Equipment:
Theodolite, EDM, and one or more pole-mounted reflecting prisms.
Theodolite, EDM, and one or more pole-mounted reflecting prisms.
Procedure:
• Set the theodolite at a control
station (northing. easting, and elevation known), and backlight on another
known control station.
station (northing. easting, and elevation known), and backlight on another
known control station.
• Set an appropriate reference angle (or
azimuth) on the horizontal circle (e.g., 0°00’00” or some assigned
azimuth).
azimuth) on the horizontal circle (e.g., 0°00’00” or some assigned
azimuth).
• Set the height of the reflecting
prisms (HR) on the pole equal to the height of the optical center of the
theodolite/EDM (Hi).
prisms (HR) on the pole equal to the height of the optical center of the
theodolite/EDM (Hi).
• Prepare a sketch of the area to be
surveyed.
surveyed.
• Begin taking readings on the
appropriate points. Entering the data in the field notes (Figure D.9) and
entering the shot number in the appropriate spot on the accompanying field-note
sketch. Keep shot numbers sequential, perhaps beginning with 1,000. Work is
expedited if two prisms are employed. While one prism-holder is walking to the
next shot location. The instrument operators can be taking a reading on the
other prism-holder.
appropriate points. Entering the data in the field notes (Figure D.9) and
entering the shot number in the appropriate spot on the accompanying field-note
sketch. Keep shot numbers sequential, perhaps beginning with 1,000. Work is
expedited if two prisms are employed. While one prism-holder is walking to the
next shot location. The instrument operators can be taking a reading on the
other prism-holder.
• When all field shots (horizontal and
vertical angles and horizontal distances) have been taken, sight the reference
backsight control station again to verify the angle setting; also, verify that
the height of the prism is unchanged.
vertical angles and horizontal distances) have been taken, sight the reference
backsight control station again to verify the angle setting; also, verify that
the height of the prism is unchanged.
• Reduce the field notes to determine
station elevations and course distances, if required.
station elevations and course distances, if required.
• Plot the topographic features and
elevations at scales.
elevations at scales.
• Draw contours over the surveyed areas.
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