Calculating a centroid in GCS vs PCS

StephenKing3 — Fri, 09 May 2025 14:26:24 GMT

Hello,

I'm using ArcGIS Pro to calculate the centroid of a polygon in both geographic (WGS 1984) and projected (WGS 1984 UTM Zone 30 North) coordinate systems. I understand that the actual location of the centroid will be slightly different between the two, even though the lat and long are almost identical. However, when comparing the output for two different polygons (one located further south than the other), the distance between the point locations for the more southerly polygon is greater than for the more northerly one. Can someone explain why that is?

Thanks.

Re: Calculating a centroid in GCS vs PCS

DavidPike — Fri, 09 May 2025 17:09:37 GMT

I'd avoid any centroid calculations of GCS features as it seems to calculate the centroid as if the lat/lon coords were transcribed onto a cartesian plane i.e. Plate Carree.

https://community.esri.com/t5/arcgis-pro-questions/centroid-of-polygon-stored-in-a-geographic/m-p/1609069#M95279

topic Re: Calculating a centroid in GCS vs PCS in Coordinate Reference Systems Questions

Calculating a centroid in GCS vs PCS

Re: Calculating a centroid in GCS vs PCS