Although visual or qualitative analysis can often reveal many patterns and information, quantitative analysis allows us to communicate our analysis in more specific terms. What is steep to us may not be very steep to someone who lives in the Andes. The field of photogrammetry, i.e., measuring phenomenon on imagery, is a complex field and beyond the scope of this course. Nonetheless, some of the mathematical techniques are similar or relatively the same.
Maps define phenomena that have a spatial element.
These elements are labeled as primary or secondary. One may also create local grids to define location. We can define a feature in relation to another, e.g., travel on a 45 degree magnetic azimuth for 1.6 km. This type of description is known as a polar coordinate. You may remember a similar concept in physics, a vector.