What would be the simplest way to arrive at a value for UTM grid convergence for a point given in UTM coordinates?
All advice I can find requires that the point be given in latitude/longitude. For example, there's a good post on this forum here:
But that would first require conversion of point information from UTM to lat/lon. That's easy to do manually using any of the many online tools available. Coding an automated solution is also doable, though tedious. I managed to put together an Excel spreadsheet, benefiting from guidance offered here:
My particular application is in QGIS, where I'm trying to use the Expression String Builder to automatically set Print Layout > Main Properties > Map Rotation to orient the map so that up is true north. Ideally I'd like to be able to use x(@map_extent_center) and y(@map_extent_center) to get grid convergence at map center, then rotate the map by that amount. The ultimate goal there is to create maps similar to USGS 7.5-minute quadrangles, to be used for orienteering in the field.
Note that I did check out the QGIS plugin Lat Lon Tools. It includes functions for use in the Expression String Builder, but those functions convert lat/lon to UTM, not visa versa.