Lab #6 - Measuring Angles with a Total Station and Distances with a Tape Measure Prior to understanding the measurement of angles and distances in the field you must first have an understanding as to what it is you are measuring from. In surveying, a known location is referred to as a point. Although you might encounter a project which has many points laid out across the site, only a few of them are very precisely laid out with minimal error in their location. These points are known as control Eoints. All other locations or points are measured or set from control points. Control points are usually set utilizing other points from a network of survey locations and points previously set throughout the country. Try to imagine that an imaginary grid has been placed upon the globe. Each intersection of that grid is a known and measured location, and no matter where you are, you are able to measure from one of those grid intersections and provide yourself a new known location. This is a very simplied explanation of where your site measurements originate from. Ultimately, the key to this is to understand that when you start your measurements, you will need a minimum of two known locations to start from. The base Eoint, where you will ultimately measure from would be a known location; however, without another known point to reference from, you will not be able to accurately orient the direction of the points. The second point used for orientation is known as a reference Eoint. The base and reference points are control points