[Mapnik-users] Regarding Japanese map rendering time

[Jin Kang]

Hi Jon,

Thanks much for your comments!

We are currently using zoom level 16. We tested up to zoom level 8 before and we were getting 1 or 2 sec for 1 tile rendering. If you could take a look at our feedbacks below, we would appreciate it.


> The rendering of the OSM data in Japan was significantly slowed down by
> the recent addition of a relation (id=1337942) describing a very large
> natural=wood polygon. This has about 100,000 nodes in the outer ways and
> another 100,000 nodes for the inner ways. This covers a large area and
> Mapnik needs to process this relation for every tile inside this area.
> 
> You might want to try temporarily removing this polygon from your
> database to see what effect it has on the rendering speed:
> 
> $ psql gis
> ...
> =>  delete from planet_osm_polygon where osm_id=-1337942;

The osm we are currently using is the one we downloaded in December last year. In our environment, we don't have osm_id=-1337942 record in planet_osm_polygon. Maybe we are using osm file that osm_id=-1337942 is not added.

Regards,

-Jin


On Jan 29, 2011, at 7:07 AM, Jon Burgess wrote:

> On Thu, 2011-01-27 at 11:26 +0900, Jin Kang wrote:
>> Hello,
>> 
>> 
>> This is Jin from Rainbow Japan and our engineer is trying to render
>> Japanese map as below but looks like it took quite time. Our engineer
>> tried to render using "generate_tiles.py" bbox = (112.73, 20.2,
>> 154.19, 45.71) area in mapnik but it took more than 1 hour to render
>> this 1 tile alone. We would like to know whether this is normal. Your
>> comments will be appreciated as usual.
>> 
> 
> The 'generate_tiles.py' script does not just create a single tile but
> lots of tiles across multiple zoom levels. It is hard to say how long
> this is expected to take unless you also say what range of zoom levels
> you are rendering.
> 
> I just tried the following parameters on the main OSM tile server and it
> rendered 955 tiles in 8 minutes using 4 threads.
> 
>    bbox = (112.73, 20.2, 154.19, 45.71)
>    render_tiles(bbox, mapfile, tile_dir, 0, 8, "Japan")
> 
> 
> The rendering of the OSM data in Japan was significantly slowed down by
> the recent addition of a relation (id=1337942) describing a very large
> natural=wood polygon. This has about 100,000 nodes in the outer ways and
> another 100,000 nodes for the inner ways. This covers a large area and
> Mapnik needs to process this relation for every tile inside this area. 
> 
> You might want to try temporarily removing this polygon from your
> database to see what effect it has on the rendering speed: 
> 
> $ psql gis
> ...
> => delete from planet_osm_polygon where osm_id=-1337942;
> 
> 
>    Jon
> 
> 
> 
>