[OSM-dev] Mapnik output resolution

Graham Jones grahamjones139 at googlemail.com
Sat Feb 6 19:48:13 GMT 2010

My apologies - this is probably more of a Mapnik question than an OSM one,
but I am using the OSM stylesheet, so I hope someone knows the answer!

I am working on a little application to generate PDF map output with points
of interest highlighted (ie to produce a 'restaurant guide' or 'tourist
attractions guide' for an area) (http://www.townguide.webhop.net).

If I select my map size to give 100 dpi resolution, the text size looks ok,
but the output is a bit fuzzy (because it is only 100dpi).  If I increase
the resolution to 300dpi by increasing the number of pixels I tell mapnik to
use the text size reduces (or maybe it stays the same in pixels, but is
smaller because I am printing at higher resolution) and it is no easier to
read - it looks like mapnik uses a different zoom level because extra detail
appears that I do not really want.
For examples please see
http://www.townguide.webhop.net/output/73/townguide_poster.pdf and
http://townguide.webhop.net/output/72/townguide_poster.pdf for the 100 and
300 dpi versions respectively.

Is there a way to tell mapnik what output resolution I want so that the font
sizes, road widths etc. come out correct at different resolutions, or will I
have to re-process the style sheet for different resolutions?.
Any pointers would be appreciated please!



Dr. Graham Jones
Hartlepool, UK
email: grahamjones139 at gmail.com
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