[Qgis-user] how to find center of polygons and/or major and minor diameters

Brent Wood Brent.Wood at niwa.co.nz
Tue Jan 12 11:13:27 PST 2021

This may be a suitable approach, not specifically the ellipse axis approach, but:

Vector -> Geometry tools -> Centroid

may do what you want, depending on exactly how QGIS calculates the centroid...

Brent Wood

Principal Technician, Fisheries
DDI:  +64 (4) 3860529

From: Qgis-user <qgis-user-bounces at lists.osgeo.org> on behalf of Azzurra Lentini <azzurralentini at gmail.com>
Sent: Wednesday, January 13, 2021 08:04
To: qgis-user <qgis-user at lists.osgeo.org>
Subject: [Qgis-user] how to find center of polygons and/or major and minor diameters

Hi to all, any suggestion on how to quickly draw the minor and major diameters of different polygons? I have a shapefile of polygons: some of the polygons are ellipses and others are similar to ellipses but not regular.

My aim is to find the center of these polygons (In this aim I was thinking to draw the 2 diameters and to use the intersection of these diameters as a center point of the polygon)

Thanks, Azzurra

Lecturer GIS University "Roma Tre"
Consultant Environmental Risk Prevention and Hydrogeology
Italy Mobile Tel.: **(39) 338 24 40 676
SKYPE azzurrahydro

azzurralentini at gmail.com<mailto:azzurralentini at gmail.com>

azzurra.lentini at uniroma3.it<mailto:azzurra.lentini at uniroma3.it>

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Brent Wood
Principal Technician - GIS and Spatial Data Management
Programme Leader - Environmental Information Delivery
+64-4-386-0529 |
National Institute of Water & Atmospheric Research Ltd (NIWA)
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