From an instrument set up at point A, the angle of elevation of point B is +16°77' while point C is +7°47'. Furthermore, it was found out that the difference in elevation between points B and C considering the effect of earth's curvature and refraction is 117.873 m. Point A is in between B and C.

Q: The elevation of point A is at 1200' above sea level. What is the elevation of point B if the flying…

A: Scale (s) = 1200/12000                 = 1/10

Q: The observed altitude of B-ursae Minoris at lower and upper culminations are 29°58′15" and 60°453"…

A:

Control Survey and Geodetic reductions

Control surveys or survey controls are used to establish reference points as a basis for various construction activities. Vertical and horizontal control points are to be established in a control survey to increase accuracy. After establishing the control points, all other types of surveys such as topographic, right-of-way, aerial mapping, construction layout, boundary surveys, and utility mapping can be worked upon so that control networks can be formed. The place from which the observations are made is called a survey station.