How to Georeference a Map

You scanned a drawing of one map found in a newspaper and now would you like to georeference it? Have you downloaded a map image from the Internet and would like to convert it into a map for your satellite navigator? Maybe I have the solution for you.

I refer to Okmap, a free program for Windows that allows you to georeference maps and, if necessary, to transform them into files for satellite navigators. It is not exactly within everyone's reach (at least at first glance) but if you are knowledgeable on the subject, you will surely find everything you need. So if you want to know how to georeference a map using it, all you have to do is continue reading.

Be vuoi scoprire how to georeference a map, the first step you need to take is to connect to the OkMap website and click on the item OkMap – GPS Mapping software to download the program to your PC. When the download is complete, double click on it to open the archive you just downloaded (okmap_10_7_2.zip) and start the program okmap_10_7_2.exe to start the OkMap installation process.

In the window that opens, first click on Yes and then OK e forward. Then accept the conditions of use of the program, putting the check mark next to the item I accept the terms of the license agreement, and click on first forward for four consecutive times and then on Install e end to complete the installation process and start Okmap.

At its first start, OkMap will be in English. To translate the program interface into Italian, you have to click on Close, go to the menu Utility > Preferences, select the item Italian give menu to tendin Language and click on the button OK to restart the software in its Italian version.

Now you can start georeference a map selecting it through the menu File> New> Raster Map. With the image loaded, click on the button Configure map and follow the guided procedure that is proposed to you to indicate first a name and a description for the map (optional) and then its technical characteristics (by clicking on Success.).

On the screen Choice of predefined projections and datums, you need to set the filter Country, type the name of the country referenced by the map in the adjacent text field (in English) and select Projection / datum of the map from the appropriate drop-down menu. When the operation is completed, click on OK to complete the wizard.

At this point, you have to calibrate the map by inserting at least three georeferencing points in it. Then select the item UTM from the box at the bottom right, click on the pencil icon located in the OkMap toolbar (New georeferencing point) and click on the map position where you want to insert the first marker.

After doing this, enter the values ​​for the point you marked in the fields of the box UTM and click on the button Add to add a new georeferencing point to the map. Repeat the operation for all the indicators to be inserted and click on the Confirm button to complete the map georeferencing procedure.

Unfortunately, the operation is not very immediate and those who are not very familiar with maps may encounter some difficulties in using a complex program such as OkMap, fortunately, however, there is a user manual in Italian that is very clear and full of images that you can consult to solve them all your doubts about the functions and methods of using the software.