On 25. 09. 11 11:24, Francesco Sacchi wrote:
Hello,
I am evaluating Mapnik as an engine to draw maps in a standalone,
multi platform, desktop application.
I need to draw maps of a relatively small portion of land (about
300x300 km), the user should be able to zoom in/out and pan with the
mouse at a speed comparable to google earth but the application have
to work even with no internet connection at all.
I wouldn't have to install a database for this job and I saw Mapnik
can work even with OSM files directly. So I installed Mapnik and
python binding on my Ubuntu and started with some simple testing.
First of all,the OSM file of the portion of land I am interested in
(http://download.gfoss.it/osm/osm/regioni/toscana.osm.bz2) is large
when uncompressed (> 500 MB).
Is there a way for Mapnik to work directly with compressed data?
Secondly, I tried the simple tutorial, here:
http://trac.mapnik.org/wiki/GettingStarted
I changed the map soruces from the Shapefile to my OSM file and the
reendering of the whole region is quite slow (>10 seconds).
Rendering >500MB of data in about 10s is not slow, I'd say. To allow
faster rendering, the low zoom levels are usually pre-rendered and
cached to disk, only higher zoom levels (from 14 or more) are rendered
on the fly. You may want to set up such a strategy for your app.
See this page as a startup for various information on how maps can be
rendered: http://wiki.openstreetmap.org/wiki/Slippy_Map
Is Mapnik the right tool for this job? And if yes, do you have any
advice on mapping format/configurations I have to use in order to
lower disk space requirements and increase performance?
Setting up a spatial database (like postgresql + postgis) will likely
improve performance instead of reading the all file if you need to
render only a part of it.
Yves
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