Considerations that influence a coordinate system

Question

Hello Everyone!

What spatial factors and analysis and display considerations influence the choice of a coordinate system (and perhaps a map projection) to map or store data for a project area?

I am a beginning ArcPro user and I am creating my first map. This is a question my professor asked us in a lab class but I really don't understand what it means. Any interpretation would be much appreciated. Hoping to have a discussion!

Thank you very much,

Addison

Tim Ormsby · Answer

Hi, another good resource for you might be https://learn.arcgis.com/en/projects/choose-the-right-projection/ It's a hands-on tutorial at an introductory level. It includes concepts and practical applications of the concepts--like visualizing the distortion caused by different types of projections.

Bnewell · Answer

I would also have a look at the below blogs to better understand coordinate systems and why they matter. It is important to grasp the difference between geographic coordinate systems and projected coordinate systems

* https://www.esri.com/arcgis-blog/products/arcgis-pro/mapping/coordinate-systems-difference/
* https://www.esri.com/arcgis-blog/products/arcgis-pro/mapping/gcs_vs_pcs/

danretired · Answer

longitude/latitude coordinates are referred to a "geographic coordinates"

As an example of the "have the influence of a datum"

Pre 1927 if you recorded a location -75, 45  (long, lat) it would have used a 1927 datum (eg description of Earth's shape).

in the year 2000, if you went to that exact location (-75, 45)  you wouldn't have been in the same spot as before because the "datum" used to describe Earth had changed.  You would have been a couple of hundred meters away from where you think you should be.

Conversely,  If you stood still for all those years in that location (work with me, pretend), you wouldn't have moved at all, but "where" you appeared to be based on the coordinates would change. 😉