I have 8 terabytes of imagery that is in either lon/lat or UTM projection that I will be using for the basis of large scale topographic maps.
I have been studying the differences between Mercator and Web Mercator, but I am still not sure what projection is more suitable for large scale (scales between 1:24k – 1:63k) topographic maps. I do understand that Mercator is conformal unlike Web Mercator which seems like an advantage.
I would like to project these datasets in UTM as I understand that is the recommended projection by United Nations Cartography Committee for topographic maps because it minimizes angular distortion at large scales (and at detail greater than 1:24k) – and because about half of my data is already in UTM.
At the same time I would like the ability to seamlessly zoom from a large geographic area (~1:250k up to 1:24k. That makes the UTM zones problematic as I will not have the capability of reprojecting adjacent UTM zones into a common UTM zone on-the-fly.
Best Answer
Web Mercator is rarely the right answer, unless you want pictures that line up with other stuff in Web Mercator.
An extract from the NGA's Implementation Practice Web Mercator Map Projection, which is worth a read in full: