I am trying to determine the formula necessary to calculate map resolution (change in lat,long per screen unit). I am interested in only WGS84 coordinate space.
Every formula I have found thus far seems dependent on a map that has predefined zoom levels, i.e. a tiled map. For example, the common formula I find is:
Map resolution = 156543.04 meters/pixel * cos(latitude) / (2 ^ zoomlevel)
How can I adjust this formula for a map without zoom levels?