1 EDM Calculations ASM 215 EDM CALCULATIONS
2 EDM Calculations HORIZONTAL DISTANCE MEASUREMENT n In plane surveying, the distance between two points means the horizontal distance. n If the points are at different elevations, then the distance is the horizontal length between plumb lines at the points. n 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) n Assume that the difference in instrument height is negligible
5 EDM Calculations DIFFERENCE IN ELEVATION (MEASURING UP HILL) n Assume that the difference in instrument height is negligible
6 EDM Calculations SLOPE ANGLE (MEASURING DOWN HILL) H = L cos n Assume that the difference in instrument height is negligible
7 EDM Calculations SLOPE ANGLE (MEASURING UP HILL) H = L cos n Assume that the difference in instrument height is negligible
8 EDM Calculations CORRECTION FOR VERTICAL OFFSET
9 EDM Calculations SLOPE ANGLE (MEASURING DOWN HILL) H = L cos n Assume that the vertical offset between the theodolite and the EDMI is negligible
10 EDM Calculations SLOPE ANGLE (MEASURING UP HILL) H = L cos n Assume that the vertical offset between the theodolite and the EDMI is negligible