Geographic Maps

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09-09-2018 11:08 AM
ChuckTurlington
Occasional Contributor II

Hello,

I am using ArcMap 10.4.1.

I have a base map that has the "GCS_WGS_1984" geographic coordinate reference system, it is my understanding that this reference system is referring to a 3d coordinate system.  However, if I export the map, I assume the map is actually projected to a flat image, especially since it appears on a flat computer screen?  If it is projected, what projection is used because it is not referred to as a projected coordinate but as a geographic type, which is somewhat confusing how the exported map is meant to be interpreted. 

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MelitaKennedy
Esri Notable Contributor

Chuck wrote: Is the flat imagery, treated with any particular projection? 

No. Some tools/functions now know to handle distances and areas differently if the coordinate system is a geographic one. If the data's using a projected coordinate system, the tools/functions normally do 2D/planar calculations. Web Mercator is projected, but online apps / web maps will usually not do planar distance calculations because there's so much distortion in a Mercator map projection.

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SimonKettle
Occasional Contributor III

A bit late to the game but I'm not sure if this blog might of help to you: https://community.esri.com/groups/coordinate-reference-systems/blog/2014/08/14/mean-sealevel 

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