[OSM-talk] Naga City in OSM Re: GML to OSM

Lester Caine lester at lsces.co.uk
Thu Apr 10 11:13:39 BST 2008


Andy Allan wrote:
>>  Something that has already been discussed is an information box for the corner
>>  of a map with reference data, but without information accessible quickly from
>>  the data how do you populate that box? Cached data on a tile by tile basis may
>>  be possible, but it still requires access to the raw data in the first place
>>  and having to search a large adjacent area just to find a country name is
>>  silly when a properly managed is_in would return it in the one database query?
> 
> I'm guessing you don't have any experience with spatial databases?
> bool ST_Contains(geometry_of_polygon, geometry_of_point) and so on?

It's because of my experience that I'm looking to reduce the number of such 
queries when - for example - you are trying to find all of the properties in 
Worcestershire. I have access to a number of LLPG databases, and while it is 
not yet possible to upload them - because of OS and other licences - I can see 
a point in the future when the NLPG database WILLl be available at which time 
we will have a step change in volume data available for the UK including every 
alley-way, public footpath and piece of land. At that point I don't think I 
want to even consider processing 10's of millions of polygons simple to 
establish which ones are in a certain area.

-- 
Lester Caine - G8HFL
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