Where can I find a good resource that teaches me

1) about the difference between proj4, EPSG and ESRI *.prj? (Why do several coordinate system definitions exist? When should I use which? How are they defined?)

2) how the conversion between these systems works in detail.

I came across these questions while encountering a problem with EPSG 2056 which I defined using the proj4 string (I wrongly assumed that the EPSG is an ID for the proj4 string). When exporting this coordinate system to a shapefile using the function st_write from the R package sf I realized that the ESRI *.prj file did not translate correctly. I assume it has something to do with the towgs84 paramter which ESRI does not recognize.

closed as too broad by PolyGeo Jan 27 at 20:28

Please edit the question to limit it to a specific problem with enough detail to identify an adequate answer. Avoid asking multiple distinct questions at once. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.

  • If you have an EPSG authority code then you should use the EPSG registry to discover what it's properties are. That is the definitive reference. Similarly an ESRI:code is defined by ESRI. To be aware, though that sometimes codes are specified as being defined by EPSG, when they are not, for example you might see EPSG:102100 the code 102100 is not defined by the EPSG authority it's a code use by ESRI and should be referenced as ESRI:102100 – nmtoken Feb 7 at 17:00
  • You can learn a bit more by looking at the wiki for the epsg tag on this question – nmtoken Feb 7 at 17:02