Module 3: Measurement by Stadia

This module focuses on using Stadia Method in determining distances and differences of elevation. It starts with a discussion of curvature and refraction which has to be considered in light of expected stadia accuracy. (This topic was not discussed further but I have such ideas to support the thought)

In this topic, we have a subtopic regarding curvature and refraction, to expound, For long sights and accurate levelling work, the effects of curvature of the earth and refraction of the line of sight shall have to be taken into consideration. Due to curvature, the points appear to be lower than they actually are; while due to refraction, they appear to be higher than they actually are. The effect of curvature being greater than that of refraction, the combined effect causes the points to appear to be lower than they actually are.

Another striking point that I can still ponder would be The level line falls away from the horizontal line of sight and the vertical distance between the horizontal line and the level line denotes the effect of curvature of the earth.

To differentiate the two ideologies, refraction is when the light being observed is bent via one of the many ways light can be refracted, while curvature means that the measurement is not made in a flat surface. For instance, measuring the distance between two points a far distance apart requires correction for the curvature of the earth. The beam of light will travel in a straight line but the distance along the curve will be longer.

Upon learning the basics, I learned that surveying doesn't only be applied in a short basis but for a longer one since it is applied in such industries like engineering, etc. As for this topic, I learned that the ideology regarding curvature and refraction can be applied in different ways.