Centroid Question

[bplus]

yeah I thought you @TerryRitchie were that far already???

Google: How to calculate the Centroid:

How do I compute the centroid in a polygon?
Write down the coordinates of each polygon vertex.
Count the vertices and denote their number by n .
Add all the x values from the vertices and divide the sum by n .
Add all the y values from the vertices and divide the sum by n .
That's it!

thats why I said compare that to your idea of mid(x, y) (xmax-xmin)/2, (ymax-ymin)/2
They might be kinda close, the same in certain cases like a circle but not always correct.