[OSM-dev] openstreet map and wms

Artem Pavlenko artem at mapnik.org
Mon Jun 18 19:45:50 BST 2007


On 18 Jun 2007, at 19:26, Frederik Ramm wrote:

> Hi,
>
>> Should be approximately trivial to make a WMS which just compiles
>> existing tiles together.
>
> If you want to offer a trivial minimum WMS compliant service of  
> limited
> value, yes. (You'd still have to do re-scaling of the bitmaps on  
> the fly
> as clients can specify a geo extent *and* image width/height with  
> their
> request and you have to comply.)
>
> The nontrivial part is that a WMS server will usually allow the caller
> to also specify the desired projection, and the server is expected to
> comply. You can cheat your way out of the projection issue by  
> announcing
> to the client that you only speak one specific projection (this will
> then lead to clients having to do re-projection based on bitmaps,
> uglifying all the fonts and so on).
>
> The proper way to do it would really be to set up something mapnik- 
> style
> that will render the desired area from an indexed database.
>
> The whole projection issue is often overlooked by us spoilt brats at
> medium latitudes and longitudes, we don't even see a lot of difference
> with various projections and seldom have a need to switch. But "one  
> size
> fits all" will not carry us forever as OSM crawls into remote areas.
> There is a reason why cartographers use tons of different projections.
>

Mapnik has got WMS 1.1.1/1.3.0 implemented in Python since 0.3. You  
can project vector data on fly, specify layers etc. Anyone can setup  
basic WMS using planet.osm/osm2pgsql/postgis/mapnik in no time. But  
why? Using 'tiles' is by far better (more scalable) way to deliver  
base maps on the web.

Cheers,
Artem


> Bye
> Frederik
>
> -- 
> Frederik Ramm  ##  eMail frederik at remote.org  ##  N49°00.09' E008° 
> 23.33'
>
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Artem Pavlenko
http://mapnik.org



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