[Tilesathome] lowzoom empty caption problem

[Johan Thelmén]

måndagen den 14 april 2008 skrev jag:
> Hi
> 
> http://wiki.openstreetmap.org/index.php/Tiles%40home/lowzoom
> 
> I have finished updating captions but tiles that do not have any caption just get a blank white tile instead of a transparant one. I guess there is a small serversetting needed or exchage of the emptytile.png file for the caption layer. Another option is to make lowzom_compostite.pl client detect this non transparent tile and replace it with a transparant one. But it should be fixed att the server I think, also to be able to use it also as slippymap overlay I guess.
> 
> What should we do?  Who can fix this?

Here is a patch to svn.openstreetmap.org/sites/other/tilesAtHome/Tiles/db.php line 41

// If no tile on transparent layer, return a blank transparent
if (layerIsTransparent($Layer)) { BlankTile("blank_transparent", TRUE); }

We are a bit unsure if we should use TRUE or FALSE to cache the result for 14days or not.
I would say TRUE (no cache) because it is so easy to serve. Maybe FALSE at a later time when we are more complete.
Untested code, please comment and check before applying.

It is probably possible to optimize this using .htaccess like this.
http://wiki.openstreetmap.org/index.php/Talk:Tiles%40home/The_blank_tile_problem
But that is probably an overkill in this case.

Attached what should be a transparent tile, taken from the coastline-error-checker.

-- 
Johan Thelmén  TeLLuS
Falun Sweden
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