TutorialsUsing Natural Earth data

If you need an overview map of a certain region, you can make one using data from Natural Earth and the free GIS software QGIS. Specifically, in this tutorial, we show how to make a vector map in Ipe format containing just the shapes of the countries, that you can use for cartogram algorithms.

Here is how:

• Download the Natural Earth data. You can get the country borders from here (look under Admin 0 - Countries). You will get an archive containing several files. One of them is a so-called shapefile (with the extension .shp); unpack that file to somewhere.

  Of course, if you need more detail than just the countries, you can also download other shapefiles from Natural Earth.

• Open the shapefile in QGIS.

• Choose a map projection. In the lower-right corner, you will see the current projection, EPSG:4326. Click it to open a dialog for picking a projection. You should choose a projection that fits the area of the world you want to see on the map.

• Remove the fill color. If QGIS exports a map containing both borders and a fill color, it will create two identical areas for every region: one for the border and one for the fill. This makes the file unnecessarily large and duplicated regions are annoying for software, so it is better to turn off the fill color.

  To do this, right-click the current layer in the Layers panel (to the left of the map), and click Properties. In the dialog, choose the Style category, click Simple fill, and in the color dropdown on the right, choose Transparent fill.

• Make a print composer. Click File > New Print Composer. Choose an arbitrary title (it does not matter anyway). This can take a while, during which the GUI will be unresponsive.

• Add your map to the print composer. Click Layout > Add Map and drag on the sheet of paper shown in the print composer. Note that the visible part of the map is determined by what is visible in QGIS's main window, so you should move and zoom the map there to show the region you're interested in.

• Export to PDF. Click Composer > Export as PDF and save this somewhere. This can also take a while.

• Convert the PDF file to Ipe. You can now use the program pdftoipe to convert this PDF file. Open a command line (Windows) / terminal (Linux) and execute pdftoipe <path to the PDF file>.

• Done! You can now open the file using Ipe.