Creating Points from Polygons (Centroids tool)
Included in this tutorial:
Accessing the Centroids tool
Centroids tool parameters, with an example
Software version in examples: QGIS
Tutorial Data: The tutorial includes demonstration with sample data available here.
Credits: L. Meisterlin (2022)
This tutorial includes creating centroid points from input polygons using the Centroids tool in QGIS.
Accessing the Centroids tool
There are multiple ways to access the Centroids tool
Through the main menu (below left): click through Vector > Geometry Tools > Centroids.
In the Processing Toolbox: Search “centroids” in the Processing toolbox or browse through Vector geometry > Centroids (below right).
Centroids tool parameters, with Example
The parameters of the centroid tool are straightforward:
Input layer: The layer for which the tool will generate points at the centroid of each feature.
Options (as checkboxes) include only considering the selected features of the input layer as well as creating a centroid for each part will generate separate point for multipart features in the input layer.
Centroids (output): Choose where (and in what format) to save the output centroids feature class, or choose to generate a temporary layer.
Check Open output file after running algorithm to add the new centroid layer to the current project.
In the example below, we create a temporary layer, with a point at the centroid of each of the features in the input polygon layer. There are four polygon features in the input layer, and thus there are four features in the output layer. The resulting attribute also includes the attributes from the input features. (In this example, the input attribute table includes a field called BoroCD.)
using the Centroids tool