How do I convert (latitude,longitude) into (x,y) coordinates?

What is the formula for real world (开发者_Go百科latitude,longitude) conversion into (x,y) coordinates?

Latitudes and longitudes exist on a spherical globe. Map X and Y coordinates exist on a (theoretically) flat map.

To convert between them, you need to "project" the spherical coordinates onto the flat map.

There are many different ways to do projections. Some are optimised for particular regions. An earlier poster mentioned the Mercator projection. This is a popular one, but has its limitations (as all of them do).

Stage one is probably to better understand your needs. What sort of latitude/longitude data do you have? What do you plan to do with it? Is your data confined to particular regions? What level of accuracy is needed? Is conversion speed important? (You may need to trade speed against accuracy).

Wikipedia has a reasonable article on UTM (Mercator) projections.