[OSM-dev] Beginner questions about mod_tile

Jaume Figueras jaume.figueras at masafi.cat
Fri Aug 8 11:26:53 BST 2008


Hi,

I'm trying to set up a map server using mod_tile, when editing the 
render_config.h file to fit my directory hierarchy there are some 
parameters I don't success to understand:

1.- IMG_PATH: 'grep'-ing all mod_tile files lead that IMG_PATH is only 
defined in render_config.h and is never used. But in the definitions it 
says that must contain blank.png and other files. Advice please.

2.- In the readme.txt file it says that the file osm-jb-merc.xml define 
the Mapnik rules. This is 'my' osm.xml file? and defined in OSM_XML in 
render_config.h. The different names cause me a bit of confusion.

3.-I don't fully understant how PLANET_TIMESTAMP and PLANET_INTERVAL 
work. PLANET_TIMESTAMP is used in the render daemon, so if the file is 
missing the daemon will rerender when a tile is 3 days old of its expiry 
(line 68 render_list.c -> planet_timestamp = 3 * 24 * 60 * 60;) if the 
file exists only rerender when the date of the file changes. I 
understood it well?  For PLANET_TIMESTAMP used in mod_tiles.c is the 
same that in render_list.c and PLANET_INTERVAL is the interval added to 
calculate the expiry date of a tile. Correct?
3b.- I suppose the I don't understand it because rerender should happen 
only if the PLANET_TIMESTAMP file is touched or the render_all script is 
executed.
3c.- While writing, I think I do not understand nothing about when 
rerender happens.... :(


4.- The update script has to be called manually (or croned). The 
mod_tile nor the render daemon will try to update the planet file.

Thank you,

Jaume.




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