The maps are generated using the worldmap package. The resulting set of vectors is converted to PNG and annotated with LUG positions using the PNG library GD.pm.
Distances from the clickpoint to LUGs are calculated as a great circle distance.
This is in part a demonstration for geotags, though currently the LUG entry form does not actually fetch Web pages and parse geo tags, but relies on submitted values. It does, however, use the same elements, and is expected to be updated to monitor Web pages on a regular basis.
After a new LUG is added, the cached PNGs are currently not automatically updated. However, a subsequent map query (zoom, center, info) will update the server cached image. A reload (shift-reload) may then be necessary to update browser and public cache before the new LUG is visible on the screen.
If there is demand, links specifically for bookmarking may be added to the views.