[OSM-dev] road data in zoom levels

Shaun McDonald shaun at shaunmcdonald.me.uk
Wed Feb 11 12:42:38 GMT 2009


On 11 Feb 2009, at 12:14, 80n wrote:

> On Wed, Feb 11, 2009 at 11:39 AM, Patrik Sjöberg <patrik.sjoberg at bth.se 
> > wrote:
> Hi!
>
> What would be the best way to get data for ways at a specific zoom
> level? I would like all roads visible on zoom 5 for instance, possibly

There is currently no predefined method for this. Each style will have  
a different set of things at each zoom level, so you will need to  
manually work out what you want.

>
> with lower resolution (fewer nodes per way). I'm guessing something
> like http://www.informationfreeway.org/api/0.5/way[highway=*] but the
> API's only seem suitable for quite small boxes.

You will also need to do the reduction in resolution yourself.

>
>
> The extended API might be what you are looking for: http://wiki.openstreetmap.org/wiki/XAPI

This will be useful for you if you are looking for small amounts of  
data. You don't say what you are trying to do with the data.

>
>
>
> We're also trying to import the planet file to our own copy of the
> database with osmosis. We have some quite new 8-core Mac Pro's here
> for development but osmosis 0.30 is compiled with java version that
> does not seem to be available on osx yet so we are trying on some old
> server instead. Would osmosis benefit enough from multicores that it
> would be strongly recommended to dedicate a Mac Pro (by booting in
> windows) for the parsing? Do you have any feeling of how long the
> import will take? We experimented with some simple ruby and sqlite and
> calculated the time required to like 3 months ^^


You can't easily compile osmosis on Mac OS X, however you can run  
osmosis on Mac OS X without problems if you set the Java Preferences  
to use Java 6 instead of Java 5. (I'm assuming that you have the  
latest version of Mac OS X 10.5 installed, and you have all the  
updates.)

If you do decide to dual boot, I would dual boot to Ubuntu instead of  
windows.

As per some previous discussion,  it is recommended to not use sqlite  
for huge amounts of data. Sqlite will only cope with a small town or  
village. Try using postgres, or  MySQL instead.

Shaun

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