Mastering QGIS - Second Edition

Converting vector geometries

Sometimes, it is necessary to make conversions among point, line, and polygon vector geometries. For example, you may need to generate point centroids from ZIP code polygons or a town boundary polygon from a line layer. Such conversions may be necessary to put the data into the most appropriate geometry for analysis. For example, if you need to determine the acreage of parcels, but they are provided in a line format, you will need to convert them to polygons to calculate their areas. Sometimes, you may want to convert geometries for cartographic reasons, such as converting polygons to points to create label points. The following tools can be found on the Geometry Tools menu under Vector:

Creating polygon centroids