[OSM-dev] spatial reference

[Artem Pavlenko]

On 2 Jul 2007, at 22:17, Jon Burgess wrote:

> On Mon, 2007-07-02 at 18:44 +0200, Martijn van Oosterhout wrote:
>> On 7/2/07, Artem Pavlenko <artem at mapnik.org> wrote:
>>>
>>> Hello,
>>>
>>> I had a chance to go through tile.openstreetmap.org  
>>> implementation and I'd
>>> like to suggest some improvements.
>>>
>>> At the moment we store x,y,z and there is a key(x,y,z). I think  
>>> we can
>>> improve by introducing spatial reference (also known as quad key  
>>> etc) and
>>> this is exactly what MS VE, Oracle and others are using. There  
>>> are a few
>>> benefits but the main one is
>>> that standard b-tree index will  'cluster' tiles spatially,  
>>> resulting in
>>> better I/O.  It will also simplify and reduce table size a little  
>>> bit.
>>
>> Look in the wiki for quadtiles, I think it resembles your proposal  
>> a lot.
>>
>> As for speed inprovement, do think it will speed it up or have you  
>> tested it?
>>
>> Have a nice day,
>
> You may also be interested to take a look at a thread from last year
> where Nick Hill tried to extend this idea by interleaving each bit of
> x/y to achieve an even higher denser bit density / smaller index.
>
> Subject: [OSM-dev] Proposal: Database accelerator and dirty tile  
> marker
> based on simple algorithm.
>
> http://lists.openstreetmap.org/pipermail/dev/2006-September/ 
> 002059.html

Wow! It is a big thread indeed, thanks. But it doesn't really come to  
any conclusions/implementations, though....hmm
I wonder if you could help to test key(x,y,z) vs key(ref) concept (if  
you have *test* tile database setup already!!)? If not, not a problem  
I'll setup something myself.

Cheers,
Artem


>
> 	Jon
>
>
>
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>

Artem Pavlenko
http://mapnik.org



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