Finding the Geographic Center of a Bunch of Points

December 7, 2018 10:33 AM

Is there a tool that lets you find a geographic center from a bunch of points on a google map?

I have a map I made in mymaps.google.com that I want to find the center of. http://www.geomidpoint.com/ used to do this but they (understandably) find the price of the new google map API access too damn high.

Is there another online tool that does this?

posted by Dr. Twist to Computers & Internet (6 answers total)

It looks like the points you mark on custom maps (you're talking about the spatial average of a bunch of points of interest, right?) show latitude and longitude. Looks like they're copy-and-pasteable. Just stick em in a spreadsheet and average all the lats and all the longs, then search the lat/long and create a new point. Not one-step but not the worst if the input number of points is on order 10 or lower.

If there are a whole lot you can export to KML which is XML-like and parse that (it's the kml.Document.Placemark.Point.coordinates field)
posted by supercres at 10:41 AM on December 7, 2018

Response by poster: I should add that it's like to use an online tool for this because I'd like to be able to have non-technical people be able to follow in my foot steps.

stick em in a spreadsheet and average all the lats and all the longs this would probably work well at neighborhood or city scale. but at high latitudes or far distances it would need to be converted to Cartesian coordinates and computed from there. plus using external tools like excel is something I'd like to avoid for the reason above.
posted by Dr. Twist at 10:52 AM on December 7, 2018

I don't think you can import your own map, but I've used http://www.whatshalfway.com/ to find a meeting point suitable for a group.
posted by madajb at 4:11 PM on December 7, 2018

Best answer: This is a very simple calculation in any GIS tool, but I don't know of a good simple consumer web service to do it. Try http://dropchop.io/? I can't test it right now but it might do the trick.

A couple of search terms that might help you find this... you want to calculate what's called "the centroid" of your points, you geometry. And you might find it easiest to export your data as KML and then do the calculation there; many GIS tools can input KML.
posted by Nelson at 12:19 AM on December 9, 2018 [1 favorite]

Yeah, DropChop should do it. It looks like it wants to import your geodata in GeoJSON format. If you can't get that directly as an export from wherever your data is now, but can get KML, you can easily convert KML to GeoJSON using various online tools like this one. Then select the features, press the button to calculate the centroid, and you're done.
posted by Nelson at 8:41 AM on December 9, 2018

Response by poster: Thanks for your help everybody! Dropchop.io did exactly what I wanted
posted by Dr. Twist at 9:10 AM on December 10, 2018