Each map, that should be properly overlaid needs to have defined a coordinate system (or Spatial reference system, which is just another name). There are thousands of coordinate systems, from which the most commonly used is WGS84. The geodata from national geospatial agencies usually come in the local coordinate system, like for example Ordnance Survey from the United Kingdom, where the system is EPSG:27700.
The dialog for choosing of a coordinate system pops up right after the upload of the source file. MapTiler automatically loads the coordinate system, unfortunately, in some geodata, it is not included. Then, you have to load it from an external file or specify it manually.
Load SRS from file
To load the SRS from a file, click on the appropriate button and assign the file. Typically used extensions are: .prj, .srs, .txt. Then, click on the “set” button and continue with adding the Georeference.
Search for SRS manually
You can search for a country, code of the coordinate system, or its name. For instance, write the UK to get the coordinate systems used in the area of the United Kingdom. Also, other keywords such as Britain or the Ordnance survey will guide you to choose the right coordinate system for your map.
For each coordinate system, there is also a list of accuracies, which you find after clicking on the little arrow next to the coordinate system name.
After you find the right coordinate system of your map, click on the set button.
If you are not sure, which coordinate system to use, skip this step and find more information at the provider of your map data. By clicking on the “change” button you can always come back and do a change.
MapTiler supports over 6 thousand coordinate systems from all over the world and loads the EPSG.io database.
Define own Coordinate system
1) Go to epsg-registry.org
2) Search for Clarke 1880
3) Choose the suitable result and click on WKT
4) Paste the definition into MapTiler as a custom projection
Setting the coordinate system in command-line is described in MapTiler manual.