[osmosis-dev] Geometries for the relations table of pgsnapshot

[Кирилл Бестужев]

What's the use of converting ALL relations into geometries? Much of them
have no relation to geometry - they are collections, routes and so on!!!

Kirill

2012/10/25 Paweł Paprota <ppawel at fastmail.fm>

> Hi Paul,
>
> I've been doing some similar work on aggregating way/node geometries and
> there are some questions that need to be answered when considering
> something like this:
>
> 1. What spatial type to store? OSM relations obviously can contain both
> ways and nodes so when you do a simple ST_Union/ST_Collect you will get a
> GEOMETRYCOLLECTION of LINESTRINGs and POINTs; GEOMETRYCOLLECTION is a bit
> problematic as it is not supported by many PostGIS ST_* functions.
>
> What I've done myself is I convert node points into closed linestrings
> with two points (X, X) thus when I aggregate node and way geometries I get
> a MULTILINESTRING which is much more useful than GEOMETRYCOLLECTION.
>
> 2. What to do about hierarchical relations (that is, relations that have
> other relations as members)? Should they be resolved down to nodes/ways?
>
> Paweł
>
>
> On 10/25/2012 02:37 AM, Paul Norman wrote:
>
>> I keep a pgsnapshot database up to date on my home server for a local
>> jxapi
>> server and also for analysis.
>>
>> I have a linestring column built for the ways table, but there's no
>> geometry
>> for relations.
>>
>> I am wondering what would be involved with getting a geometry column built
>> for the relations table.
>>
>> I expect this would slow down updates, but it would be invaluable to for
>> analysis.
>>
>> I believe Ian Dees mentioned to me something about some work that had been
>> done on this.
>>
>> Is there anything that I could do to help? I have minimal java knowledge
>> and
>> some postgis knowledge.
>>
>>
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>>
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