Module 5 - Projections Part I

This week in lab, we were learning about projected coordinate systems, which are map projections that use mathematical formulas to relate spherical coordinates to 2-dimensional planar coordinates. We were first provided with data showing a map of the counties of Florida in Albers equal-area conic projection, and we wanted to display this data in the Albers and two other coordinate systems. We used the project tool in ArcMap to do this. Found in ArcToolbox --> Data Management Tools --> Projections and Transformations, the "project" tool reprojects a starting data layer into a different coordinate system (the original layer is not lost). Using the project tool, we created the map of Florida counties in a total of 3 coordinate systems: the original Albers projection, a UTM projection, and a state plane coordinate system. Each of these was placed in its own data frame, so we could display all three at once on our map.
We created another data layer out of 4 selected counties within Florida, and created another value showing the geographic area of those counties (for each data frame). We then can see how the area for each county varies depending on which coordinate system is used. This is due to distortion that comes from projecting a three dimensional object into a two dimensional representation. We wanted to display this and "own our map", and mine is below.

First, I wanted to center and label the three coordinate system figures on my map. I made sure that the scale of my three figures were the same so that I could use the same scale bar for all three. In my legend, I show the 4 selected counties and the areas in square miles so one can see at a glance the difference in area between projections. We were asked to create a table showing the difference in area for different coordinate systems, so I created one in Excel and copied and pasted it to my map. I placed a caption to explain to the end user a little about what they were looking that, although I tried to make it clear with the title as well. After that, I placed my essential map elements.

The main thing I took from this assignment is the importance of choosing a proper projection based on the geographic location and the extent of the area that I'm interested in.