[OSM-talk] Geofabrik Download Server Update

Matthias Julius lists at julius-net.net
Wed May 4 08:43:54 BST 2011




Frederik Ramm <frederik at remote.org> schrieb:

>Hi,
>
>Matthias Julius wrote:
>> 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.
>
>Yes. I somewhat fear the number of "i am getting a strange error in my 
>program" emails that this would cause.

Yes, that is why there would need to be a tool that can trim incomplete ways.  Maybe as an osmosis task.

>
>Merging extracts is a niche operation and not the main purpose of what
>I 
>am doing. 

Is it that small of a niche?  There are probably plenty of reasons why someone might be interested in an area that crosses an extract boundary.

You might save a lot of bandwidth if people who for example want to produce a Garmin map for BeNeLux do not ha e to download the whole of Europe. ;-)

Of course, this all speculation.  Maybe I am the only one that cares for mergeable extracts.

>For someone who wants to mix and merge at will, it would be 
>much better to simply divide the world in lots of squares and select 
>from those. The expensive polygon cutting could be dropped completely. 
>It is possible that a process for doing that can be derived from those 
>who do regular Garmin maps. If done properly, it would even be possible
>
>to have a web interface where you can select your area of interest, and
>
>a matching extract is then merged live from pre-made squares...
>
>> 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.
>
>Yes but if you start looking at this closely then the only thing you 
>know is that the boundary must be somewhere between nodes X and Y so 
>that doesn't get you far.

It is more a cosmetic thing.  If for example someone wants to render a map for a certain extract they will have some long ways sticking out here and there, which is ugly.

Matthias




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