Centroid

Replace each feature's geometry with a single point at its geometric center.

basic

A centroid step replaces each feature's geometry with a single point at the feature's geometric center (ST_Centroid). Attributes are kept; only the geometry changes from polygon (or line) to point.

Use when a downstream step or rendering wants point geometry: labeling at a single anchor, clustering, point-symbol rendering of a polygon layer, or input to a join that expects points.

Inputs

  • Source layer. Any geometry type. Points stay points at the same location; lines become midpoints; polygons become geometric centroids (which can fall outside a concave shape).

Output

A new layer with point geometry. Attributes copied verbatim.

How to use it on its own

From Analyze (guided)

  1. Open a data layer and switch to the Analyze tab.
  2. Click Centroids for this layer.
  3. Optionally edit the title.
  4. Click Create derived layer.

The portal creates a private derived layer and opens it. Expect a short server job, not an instant browser result. The in-browser SQL starter still offers ST_Centroid for ad-hoc queries; the guided control is the honest path when you want a saved layer.

Share a direct link with ?tool=centroid (and &layer=<sublayerId> on multi-layer items) plus #data. From a map layer kebab, choose Centroids… for the same path in a new tab.

From the new-item wizard

  1. New-item wizard → Derived layer.
  2. Pick a Source.
  3. Add a Centroid step.
  4. Save.

Example

You have a parcel polygon layer and want a "parcel centroids" point layer as the click target on a basemap-style map (polygons as decoration, points as the interactive layer). Use the Analyze shortcut or a Centroid step on a derived layer.

Notes

  • Geometric centroid only. The portal runs PostGIS ST_Centroid. Pole of inaccessibility and bounding-box center are not separate options on this path.
  • Centroid of a multipart geometry is one point: the centroid of the combined geometry. Not one per part.
  • Linestrings have centroids too. The midpoint of the line.
  • NULL geometry features produce NULL output points and drop from rendering.