[OSM-talk] rendering some large maps, e.g. whole world

[Matt Amos]

On Sat, Apr 18, 2009 at 9:34 AM, D Tucny <d at tucny.com> wrote:
> 2009/4/18 Torsten Mohr <tmohr at s.netic.de>
>> Has anybody got any experience with changing osm.xml to create maps
>> that look fine when printed (readable text, ...)?
>>
>> Or do i worry too much and printing PNGs looks just all right?
>
> The maps are typically rendered for viewing on a screen, so, text and
> symbols may appear too small when printed, you would likely need to adjust
> their size for print, but, how much you adjust it can be a taste thing...
>
> I haven't done it with a map myself, but others have and hopefully they will
> be able to contribute here with their experiences...

i've seen two approaches:

1. render to PDF/PS and rasterise/print that at whatever scale you
want. this means no mucking about with the style file, but some
features (e.g: transparency, text halo-ing) sometimes don't come
across the same as they do on the rendered tiles.

2. alter the style file so that everything is ~3 times bigger. this
means everything will render right, but is a pain to do by hand.

both approaches give comparable results. for the best results, replace
the icons with a scalable icon set rendered at 3 times their normal
size.

>> 2.
>> When rendering the whole world with coordinates like this:
>>
>> # unused:   ll = (4.5, 46, 16, 56) # Germany
>>    ll = (-180.0, -90.0, 180.0, 90.0) # World
>>
>> Then i just get an empty file (just background).
>>
>> Is this related to the scale denominators in osm.xml?
>
> It likely is a combination of the scale and potentially a lack of the coast
> shapefiles... The lowest level of detail just has the coast line rendered
> from the shapefiles...

i think its more likely to be that -90/+90 lat project to infinity in
the mercartor projection. if you want a square image, use
-85.0511/+85.0511 lat. see also
http://wiki.openstreetmap.org/wiki/Slippy_map_tilenames#X_and_Y

cheers,

matt