[OSM-talk] Geofabrik Download Server Update

[Matthias Julius]

Frederik Ramm <frederik at remote.org> writes:

> Matthias,
>
> Matthias Julius wrote:
>> But, I need to point out again that theese extracts are not quite as
>> useful as they could be, IMHO. Unless something has been changed,
>> ways that cross the bounding polygon are trunkated at the last node
>> inside the polygon.
>
> I have started to slowly introduce extracts built with the
> --complete-ways option, but not all extracts have that yet. In Europe,
> all sub-country extracts have it but countries don't, so you should be
> able to join two German Laender or two French regions, but you will
> encounter problems when joining a part of Germany with a part of
> France. I'm working on that but even a box with 90 GB of RAM disk has
> a hard time splitting Europe into countries with --complete-ways.

One option would be to run osmosis with clipIncompleteEntities=false
(the default).  That would not increase the burden on your box and still
allow the extracts to be merged.  Of course, this would leave it up to
the data consumer to deal with the incomplete ways and relations.

In some ways this is even preferable because it would preserve the
boundary of the extract.  Otherewise you get a fuzzy boundary and the
consuming tools have no way of knowing the original boundary.
Alternatively, the boundary polygon could be stored in the file.
Unfortunately, so far the file formats only support rectangular bounding
boxes.

>
> Note that two other preconditions exist for a successful join of
> neighbouring regions. First, the polygons I use for cutting must
> actually overlap. They usually do but every now and then I encounter a
> little bit of no man's land due to polygon simplification. Second, you
> have to use software that properly eliminates the double elements; I'm
> not sure if Osmosis does that.

If it doesn't than this is the chance to fix it.

Do your polygons really overlap?  I think it would be ideal if the
shared the nodes.

Matthias