One of the most common routines in the use of Geographic Information Systems is the construction of spatial layers from information from the field. Whether this represents coordinates, parcel vertices, or elevation grid, the information usually comes in comma separated files or Excel spreadsheets.
1. The geographic coordinates file in Excel.
In this case, I am trying to import the human settlements of the Republic of Cuba, which I have Diva-GIS, which by the way is one of the best sites to download geographic data from any country. As you can see, columns B and C contain the information regarding latitude and longitude in the form of Geographical coordinates.
2. Import the file into QGIS
To import the coordinates of the Excel file, it is done:
Vector> XY tools> OpenExcele file as attribute table or Point layer
In case the file is saved with an .xlsx extension, the browser will not show it, as it only filters files with an .xls extension. It is not a problem, we can apply old DOS techniques and write in the name change, the filter: *. * (asterisk dot asterisk) and we do Enter; this will allow all the files in that location to be seen. We could have just written * .xls and it would have filtered only files with the .xls extension.
Then we have a panel in which we must indicate which column corresponds to the coordinate in X, in this case we choose the column of length, the column of latitude for the coordinate Y.
And there we have it. The query shows that the layer has been saved with the data contained in the Cuban human settlements file, which includes the name, latitude, longitude, classification, and administrative province.
3. Create polygons from coordinates
In case, we want not only to import the vertices but also to create a polygon in the order of these coordinates, we can use the plugin Points2One. This plugin allows you to identify how the destination layer will be called, if what we will import will be built as lines or as a polygon.