Is there a way to force mapnik not to generate empty tiles? And create instead a symbolic link for that??? Update Sorry for DUMM question. So how to do that generate_tiles.py will not save empty tiles? This question is marked "community wiki". asked 06 Nov '11, 07:54  Gevork wikified 23 Nov '11, 12:49 |
3 Answers:
I don't have a direct answer, but in practice I add a command at the end of the generation for removing these empty tiles: find tiles/ -size 116c | xargs rm answered 06 Nov '11, 21:48  NicolasDumoulin showing 5 of 7 show 2 more comments |
Mapnik doesn't generate tiles; Mapnik is a library only. It is the program that calls Mapnik - e.g. generate_tiles.py or renderd or tirex or something else - that generates tiles, or maybe metatiles. Mapnik has no way of signalling to these calling programs that it has just generated an "empty" tile (anyway, in our standard OSM style, only sea tiles are really "empty", everything else has at least a land polygon drawn). Read the thread Not saving empty Mapnik tiles on the osm-dev mailing list for more information. answered 06 Nov '11, 10:06  Frederik Ramm ♦ |
I don't think that "only sea tiles are really empty" - in some cases it depends of network connection when Mapnik receives "empty" blue tiles. answered 07 Jun '13, 13:41  nedol |
@NicolasDumoulin do you add this line in the end of generate_tiles.py ????
Well, no, it is a bash command (linux). But I think you can achieve the same in pure python as follow:
@NicolasDumoulin when I make find tiles/ -size 116c | xargs rm I get rm: missing operand
here is the output marmur@marmur-Extensa-5635ZG:~/tiles$ find yerevanMap/ -size 116c | xargs rm rm: missing operand Try `rm --help' for more information. marmur@marmur-Extensa-5635ZG:~/tiles$
Any idea why???
I think it is because the result of the command find is empty, you can check it by removing "| xargs rm" from the command. Maybe the size value isn't correct. I've found the "116" by looking at the printed size of my empty tiles with the "ls -l" command.
@NicolasDumoulin -rw-rw-r-- 1 marmur marmur 139 2011-11-23 00:51 0.png I get this... so should it be -size 139c???
@NicolasDumoulin thanks! it worked, found out that empty tiles was not 139 but 103 by me.... deleted like a charm! once again, thank you very much
be aware that empty sea tile, empty land tile, or any other "empty" tile that has only one color in it, may all have exactly the same size.