I'm exporting data from a program into a .csv for RStudio, which will then go into ArcMap.
I haven't done this before and I've been given two projection options which are:
- WGS 84 [EPSG:4326]
- WGS 84 / UTM zone 37N [EPSG:32637]
What is the difference between the two of them and how do I know which one I need to use?
Best Answer
EPSG 4326 is a coordinate system of latitude and longitude based on an ellipsoidal (squashed sphere) model of the earth. Its not really a projection.
EPSG 32637 (and any of the "UTM Zone" projections) is a projection of the round earth onto a flat surface, and has coordinates in metres. Its only accurate within the area of the zone, which is a range of longitudes depending on the zone number. Calculation in EPSG 32637 such as distance and direction can be done using flat geometry like Pythagoras' theorem for distance and simple products for area. To truly compute distances or areas on the curved surface of the earth you would use EPSG 4326 and more complex formulae for distance and area. ArcMap can probably deal with either, as can the spatial packages for R.
Its impossible for us to say which one you need to use since it depends very much on how much precision you need and what you are going to do with the data anyway.