[OSM-dev] Usual rendering time for Mapnik on World Db

[Mayeul Kauffmann]

Hi
It's maybe hard to compare without knowing which tile you render, at
which scale, etc.
I cannot answer for Mapnik but I can for QGIS (Mapserver): IMHO I think
it is possible to render in a faster way.
You can see yourself with on the fly rendering with QGIS Mapserver here:
http://gis.uster.ch/webgis/
(Front end is QGIS js client).
On the first of the 4 applications, on the fly rendering is generally
done in 1 to 4 seconds (1900x1200px).

I do not know the technical specs of the above server. But I can speak
for my (old) home OSM server. The last of the tiles (very dense urban)
shown on the following link took about 80 seconds; the one just before
it is bigger but took 10 seconds only:
http://www.qgis.org/wiki/OpenStreetMap_data_rendered_with_QGIS

80 seconds:
http://www.qgis.org/qgiswiki/images/b/bc/QGIS_OSM_Grenoble.png

10 seconds:
http://www.qgis.org/qgiswiki/images/2/2f/QGIS_OSM_f148.png

Above time is for a quite old computer (CPU is 9 years old: AMD Athlon
XP 1600+ ; RAM was not an issue). A significant part of the rendering
time was for labelling and contour lines. My QGIS_OSM_Grenoble.png tile
is so dense that some parts are barely readable, the same area on mapnik
has less graphic content, so similar rendering should be faster.
Typically, except for very dense urban area (e.g. Milano, Italy), my old
machine can serve on the fly with a good user experience: see video
here:
http://www.youtube.com/watch?v=NBBYtH2svw0
(speed was doubled after recording).

Technical details on the above:
QuantumGIS mapserver can do the exact rendering as QuantumGIS desktop
(it is the same engine); I believe the mapserver is faster for this (but
I preferred a homemade python script running in QGIS desktop to generate
my tiles). For my OSM tiles, I used methodology described below (with
some tricks to improve performance):
http://wiki.openstreetmap.org/wiki/Osm2postgresql
http://www.qgis.org/wiki/Using_OpenStreetMap_data#Optimization_tips

Hope this shed some light on on-the-fly OSM rendering for the web.

Regards,
Mayeul

Le vendredi 10 juin 2011 à 17:44 +0200, Stefan Menzel a écrit :
> Hello, 
> 
> as you might have noticed on my former questions I’m setting up a
> tileserver. This tileserver is part of my diploma thesis for
> loadbalancing in p2p Networks. Its running on an VM at my university.
> So I’m not aware of the HDD specs. But it has a  CPU 8 Core an 8GB
> Ram. I’m surprised by the rendering time.  Rendering tiles on low toom
> levels  takes a long time. Up to 600 sec so I get a timeout on tirex.
> Is This normal. Could a single pc handle rendering on demand without
> any caching?
> 
>  
> 
>  
> 
> Best regards
> 
> Stefan 
> 
> 
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