Simple Surveying Tasks - Extrapolating a Straight Line - Polar Stake-out of a Point

Surveying Made Easy

Simple Surveying Tasks | 23 Extrapolating a Straight Line 1. Position the instrument at point B. 2. Target point A, transit the telescope (i.e. reverse it) and mark point C1. 3. Turn the instrument 200 gon (180°) and target point A again. 4. Transit the telescope again and mark the point C2. Point C, the mid-point between C1 and C2, corresponds exactly to the extrapolation of the line AB. A line-of-sight error is responsible for the discrepancy between C1 and C2. Where the line of sight is inclined, the influence of the errors is a combination of target error, tilting-axis error and vertical-axis error. Polar Stake-out of a Point The setting-out elements (angle and distance) here relate to a known point A and to a known starting direction from A to B. 1. Set up the instrument at point A and target point B. 2. Set the horizontal circle to zero (refer to the user manual). 3. Rotate the instrument until a appears in the display. 4. Guide the reflector carrier (person) into and along the line of sight of the telescope, continually measuring the horizontal distance until point P is reached. A B C1 C C2


Surveying Made Easy
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