[jillesvangurp]

I spent some time doing adapting some geometry algorithms to work with geospatial coordinates a few years ago. The problem with the poles is that latitude converges to 90 degrees whereas longitude degrees are all over the place if you move even slightly. This combined with precision issues with floating point math causes all sorts of issues.

A good example is a simple algorithm I did to draw circles on a map by turning them into polygons: https://github.com/jillesvangurp/geogeometry/blob/master/src...

This works perfectly fine if you stay away from the poles but if you get close enough the circles become a bit irregular. The algorithm tries to work around some of the issues but the results don't look pretty.

Other issues I encountered were several datasources with invalid degrees due to rounding errors. This is an issue along the dateline (180 degrees longitude). E.g. 180.0000001 degrees is invalid.

Another fun edgecase in geo is null Island, a fictional island of the coast of Africa at (0,0) that has become a fun little easter egg in many datasources. A friend of mine dedicated this website to it: https://www.vicchi.org/2014/04/05/welcome-to-the-republic-of...