Practical GIS

Using other projections

Leaflet can use some projections out of the box, of which two have cartographic significance--EPSG:3857 and EPSG:4326. The default projection is the Web Mercator, while the WGS 84 projection has to be specified in the map's crs property. The crs property's value must be a valid Leaflet projection object. This object contains methods to transform coordinates around and has predefined zoom levels fitting the given projection, among other things. Let's try out the WGS 84 projection on our road map first:

• Extend the maps object with a function corresponding to the ID of our fourth button. The function should be almost the same as the other road map function. The only difference is that the map should contain an additional ...