Template:Location map/Creating a new map definition

This guides explains how to create map definitions for the family of templates.

Map definition data
The templates utilize any one of a set of map definitions. These are not forks but rather auxiliary pages and must have names following the pattern "Module:Location map/data/location" or "Template:Location map location", where location is the name of the area covered by the map. The template space is supported only for backward compatibility; all new map definitions should be created as modules. Important: If a new map has the same projection and boundaries as the old map (such as File:Iraq location map.svg and File:Iraq location map2.svg), a new definition should not be created; instead, the old definition should be used with the AlternativeMap parameter. To create a simple map definition module using an image of a map with an equirectangular projection having the equator as its standard parallel (aka plate carrée, “unprojected”, lat/lon projection):


 * 1) Create a new map image and upload it to Wikimedia commons or find an existing map on the same site.
 * 2) Create a module named Module:Location map/data/location, copy the content below into it and substitute the appropriate values.
 * 3) Create a page named Module:Location map/data/location/doc and follow the instructions under.

As an example of a map that uses an equirectangular projection, we use Module:Location map/data/Belgium. Please do not experiment using active templates.

Maps of this type will work for small to mid sized areas. Module:Location map/data/USA Alabama is another example of a map description that uses an equirectangular projection. Notice that the image of the country is not what most would expect.

Advanced projections
Maps that use other projections, such as Module:Location map/data/USA, which uses an equidistant conic projection. require formulas which are used to calculate the  and   coordinates for the location mark. Understanding these formulas requires a familiarity with the subject, so you are more than welcome to skip this section.

The input $1 is the latitude and $2 is the longitude, both in decimal form. The expression follows the syntax of ParserFunction "#expr". The two output coordinates are defined such that the formula for  evaluates to 0 for the left edge of the image and 100 for the right edge; the formula for   evaluates to 0 for the top edge and 100 for the bottom edge.

Documentation
It is easiest to use the de facto template at Template:Location map data documentation to generate the documentation page. Here is another example of what the documentation might look like:

{{#tag:pre|

{{Location map data documentation|image=
 * examples=

Location map, using default map (image)


Location map many, using relief map (image1)


Location map+, using AlternativeMap


}}

}}