[OSM-talk] Mapnik: strange prioritisation/appearance of place names

[Woll Newall]

In the OSM Mapnik slippy map, the rendering of place names seems to be  
rather "random" at different zoom levels. Cities seem to appear and  
disappear as I zoom in, and 'large' cities don't appear but 'tiny'  
ones do.

I can see the "city" nodes in the database (in Potlatch) but the  
rendering of them is inconsistent at different zoom levels.  It's  
difficult to guess what is happening from the visual appearance - does  
Mapnik also get city names from some other database at different zoom  
levels that could be complicating things?

Examples, (with a comparison with Google, for those that don't know  
this area of Japan):
1) Zoom level 8: Maebaru appears, but Fukuoka doesn't. Maebaru is a  
small city, Fukuoka is very large.
http://tools.geofabrik.de/mc/?mt0=mapnik&mt1=googlemap&lon=130.36277&lat=33.56957&zoom=8

2) Zoom 9: Fukuoka appears (so maybe Mapnik was not rendering Fukuoka  
because it clashed with Maebaru at zoom 8?)
http://tools.geofabrik.de/mc/?mt0=mapnik&mt1=googlemap&lon=130.36277&lat=33.56957&zoom=9

3) Zoom 10: Fukuoka disappears again! (Although it shouldn't be  
clashing with Maebaru at this zoom level)
http://tools.geofabrik.de/mc/?mt0=mapnik&mt1=googlemap&lon=130.36277&lat=33.56957&zoom=10

4) Zoom 13: Fukuoka still not there (and it never seems to appear at  
any higher zoom levels)
http://tools.geofabrik.de/mc/?mt0=mapnik&mt1=googlemap&lon=130.38423&lat=33.57744&zoom=13

Any ideas? Have the city nodes been added in a way that means Mapnik  
can't rendered them correctly? Does it need more info?

PS: Is there a more appropriate place for question about the OSM  
Mapnik slippy map appearance to be posted, or is the appropriate list?

Cheers,
Woll