[OSM-dev] Geofabrik downloads to change multipolygon handling

[Éric Gillet]

This seems like the best way to go about this, thank you for providing and
updating such an useful tool !

2017-01-16 23:35 GMT+01:00 Frederik Ramm <frederik at remote.org>:

> Hi,
>
>   this is just a small heads-up. The Geofabrik downloads (regional
> .osm.pbf extracts for various continents, countries etc) will switch to
> a different software stack later this month. We currently use
> osm-history-splitter which is based on an older version of Osmium, and
> will in the future use a new feature offered by the osmium command line
> tool and the newest Osmium version instead.
>
> This will enable us to change the handling of relations in the extracts.
>
> Currently, relations are included in the extracts if one of their
> members lies (partially) inside the area; but members of the relation
> that lie fully outside the area are not considered.
>
> This has adverse effects when large multipolygons cross the border, for
> example Lake Constance not be fully contained in any of the Germany,
> Austria, or Switzerland extracts.
>
> In the future we will be able to include all members of multipolygon
> relations that have at least one member (partially) inside the area.
> This will only be done for multipolygons and not for other relations
> (like boundaries or routes). Therefore, water bodies, forests etc. that
> cross the boundary should in the future be fully contained in the extracts.
>
> This comes at a price of a slightly larger extract but the difference is
> negligible. On the day we make the switch, all regional .osc files will
> have a slight size bump becasue all the missing bits and pieces required
> to complete the multipolygons will be contained in them.
>
> Bye
> Frederik
>
> --
> Frederik Ramm  ##  eMail frederik at remote.org  ##  N49°00'09" E008°23'33"
>
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