title: OpenLayers: Get resolution of map in a given projection (4326)
body: <p>I'm using OpenLayers to display OpenStreetMap maps. (Though, I'd assume this should be general enough to work for any map product...)</p>
  
  <p>I'm displaying some very sophisticated vector overlays, and the amount and resolution of the features I'm returning from the server via GeoJSON to overlay has proven too much for many computers.</p>
  
  <p>What I'd like to do now instead is to only send data befitting the resolution of the current zoom. This should be relatively easy to do using the <code>getResolution</code> and <code>calculateBounds</code> methods on the <code>Map</code> object. <code>calculateBounds</code> returns a Bounds object that then can be transformed between the map projection and display projection.</p>
  
  <p><strong>How do I transform the resolution into my desired projection (4326 in this case)? Is there a built in way of doing this or do I have to run the resolution against a known formula?</strong></p>