How to

Position of the map (Georeferencing)

Position of the map - Georeferencing

What is the difference between pictures and map is the information about its geographical position. Therefore, to create maps, it is necessary to define a coordinate system and its geographical position.

MapTiler automatically loads the geographical position system, in case it is known. If not, you will have to assign it manually. The dialog for assigning of a geograhphical position pops up right after setting of the Coordinate system. There are several ways, how to do it:

georeferencing

Assign Location Visually (Georeferencer)

For pictures that are missing Geographical information, the easiest way how to get it is to assign the control points. Click on the button “Assign Location Visually” and you will get to the screen with 2 maps. You you need to do is to assign control points on the same places on both maps. Minimum number of control points is 3, however, the more control points you assign, the more precise the result will be. The whole process is illustrated on this tutorial:

Load from external file

Many maps have their position saved in the the external files. Usually, these are with extensions .wld, .tfw, .jgw, .pgw, .gfw, or exported from GIS software such as OziExplorer or MapInfo (extensions .map, .tab). If you have such file, just click on the import button, choose the file, confirm, and the Georeference will be loaded.

georeferencing

Specify Bounding Box

For maps with orientation to North, it is possible to specify the Bounding Box, which is a rectangle, that creates a border of the map itself. The Bounding Box has to be specified in this order: West, South, East, North. In this case, the values -180 -90 180 90 cover the whole world. Assigning a position via bounding box is illustrated on the following tutorial:

Geotransformation

To assign affine transformation directly, you can specify a world file as 6 numbers.

Change

In case you are not sure about the Georeference, or you map is not positioned correctly, you can always come back and assign the geographical position again by clicking on the “change” button.

georeferencing