I have put together a cities database from MaxMind and it includes the lat/lng values for each city in the database. I have also put together a map of North/America and I would like to have a icon appear on the x/y coordinates of the map which are derived from the lat/lng coordinates of the city database record.
From my understanding I need to find the left/top bounds of the map first (lat/lng -> x/y) and then use that as a difference for the linear relationship between any of the north american city x/y coords. Finally, depending on the size of the map, its just a few simple division and subtraction operations to figure out where to place the point.
However I can't seem to figure out how todo the following:
- I'm not sure what the lat/lng mapping system is. How do I find this out?
- Using a JavaScript library, how do I convert the lat/lng to pixels for the 0,0 coord and each of the city coords. I've tried Proj4js, but they require that you specify your coordinate map types and so on. Here is another question that asked something similar.
Convert long/lat to pixel x/y on a given picture
Any ideas?
-- EDIT --
The output map (of North America) is a continuous cylinder: Miller cylindrical projection. http://en.wikipedia.org/wiki/Miller_cylindrical_projection
