[OSM-dev] Do we need world boundaries for small areas?

M∡rtin Koppenhoefer dieterdreist at gmail.com
Mon Jun 20 18:01:09 BST 2011


2011/6/20 Parveen Arora <mail at parveenarora.in>:
> On Mon, Jun 20, 2011 at 9:54 PM, M∡rtin Koppenhoefer
> <dieterdreist at gmail.com> wrote:
> Hi Koppenhoefer
>> The shapefiles are used in this layer (in inc/ ):
>> http://svn.openstreetmap.org/applications/rendering/mapnik/inc/layer-shapefiles.xml.inc
>>
>> As you can see the simple boundaries are used only in z1-3 and the
>> populated areas in z3 and 4. There is also a shape called "built-up"
>> used in z8-10 which I am not sure what it is, but it might be also
>> populated areas. Above z10 there is only OSM-Data (and coastlines)
>> used.
> So means that all are required to generate the map below z10.
> There are files of populated places, admin boundary lines, processed,
> shoreline and world boundaries spherical.
>
> what is the meaning by spherical world boundaries.


I'd guess that "spherical" is a reference to spherical mercator, but I
don't actually see the word "spherical" in the style-sheet for the
shapefiles I linked above. Actually for rendering the world you only
"need" the coastlines (which are used to overlay land over the
ocean=canvas). There is 2 files of them for different detail. The
other files contain simplified data of what is (mostly) in higher
resolution / acuracy in OSM, so they only speed up rendering, but with
modified stylesheets you can also do without them.

cheers,
Martin



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