[Tilesathome] Empty land tiles

[Martijn van Oosterhout]

On 8/8/07, spaetz <osm at sspaeth.de> wrote:
> While purging the blank tile database, I searched for small png files and found tons like this one:
> http://tah.dev.openstreetmap.org/Tiles/tile/7/71/63.png
> which is a real uploaded png file as can be seen from the info:
> http://tah.dev.openstreetmap.org/Tiles/info.php?x=71&y=63&z=7&layer=tile
>
> But it's simply empty land which should never have been uploaded. It was uploaded on 2007-06-02, so it's rather recent as well. Question:

There was also a more esoteric way to get this: when it detects a
blank tile t at h creates a hard link from the "reference" blank tile.
IIRC lowzoom did not used to check if a tile existed before creating
it, thus occasionally it would overwrite your "reference" blank tile
with a real blank tile, causing all blank tiles from then on to be
broken.

I had this happen to me once, at which point I added a check into the
source (and added an unlink), at which point at least one other person
noticed their reference blank tile was also corrupted.

Have a nice day,
-- 
Martijn van Oosterhout <kleptog at gmail.com> http://svana.org/kleptog/