1 EDM Calculations

ASM 215

EDM CALCULATIONS

2 EDM Calculations

HORIZONTAL DISTANCE MEASUREMENT

In plane surveying, the distance between two points means the horizontal distance.

If the points are at different elevations, then the distance is the horizontal length between plumb lines at the points.

When using an EDM device, corrections to a horizontal distance still need to be made.

3 EDM Calculations

REDUCTION OF EDM SLOPE DISTANCE TO HORIZONTAL

4 EDM Calculations

DIFFERENCE IN ELEVATION(MEASURING DOWN HILL)

Assume that the difference in instrument height is negligible

L

H

d

H L2 d2

5 EDM Calculations

DIFFERENCE IN ELEVATION(MEASURING UP HILL)

Assume that the difference in instrument height is negligible

L

H

d

H L2 d2

6 EDM Calculations

SLOPE ANGLE(MEASURING DOWN HILL)

L

H

H = L cos

Assume that the difference in instrument height is negligible

7 EDM Calculations

SLOPE ANGLE(MEASURING UP HILL)

L

H

H = L cos

Assume that the difference in instrument height is negligible

8 EDM Calculations

CORRECTION FORVERTICAL OFFSET

9 EDM Calculations

SLOPE ANGLE(MEASURING DOWN HILL)

L

H

H = L cos

Assume that the vertical offset between the theodolite and the EDMI is negligible

10 EDM Calculations

SLOPE ANGLE(MEASURING UP HILL)

L

H

H = L cos

Assume that the vertical offset between the theodolite and the EDMI is negligible