Update!

As of July 25 – joto did the manual override! So the problem is resolved, at least for now. We still need to deal with the “but MY bay isn’t really a coastline” recurring problems, but now we can deal with them individually, rather than trying to address a six month backlog.

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So, I accidentally wrote a wall of text yesterday in the IRC channel, and rory asked me to copy it here.

It was prompted by this question:

15:28 what is the rio plata thing about?

I responded:

johan_: So, the coastline rendering process used for openstreetmap.org is complex. and involves multiple semi-independent groups.

One group produces the planet.osm file, containing all the OSM data.

A different group (well, it seems to mainly just be joto), runs an independent server at https://osmdata.openstreetmap.de that processes the planet.osm data into a set of shapefiles defining the world coastlines.

Then a third group (back within osm.org) uses that data to render the map displayed by default on openstreetmap.org, known as Carto.

The osmdata script that does the processing includes an automatic cut-off that marks the produced shapefiles as invalid if the maganitude of changes since the last valid results is beyond a certain amount specifically, 0.0000015 (I’m not sure in what units, exactly). https://github.com/fossgis/osmdata/blob/master/scripts/coastline/compare-coastline-polygons.sh#L13

And the third group independently choses to obey this marking, and only apply shapefiles that have been blessed by this script.

There is an option to manually override the cutoff (by simply deleting the data it is comparing to), but joto, reasonably enough, will only do that with a clear, well-documented demonstration of a consensus among mappers that such a larger change is needed.

This mostly works.

Recently, specifically on January 10, 2020 – it didn’t.

… See full entry