[OSM-dev] Filled oceans in tiles at home - request for development work

Frederik Ramm frederik at remote.org
Mon Jan 22 14:21:26 GMT 2007

Hi Martin,

> I'm doing some stuff with this. I'll update the Wiki as appropriate.

On the Wiki you say:

> Initial estimates indicate that around 200,000 zoom-12 tiles will  
> have to be indidivually drawn, whereas the remainder of the 16  
> million will be constant colour.

I have done a bit of work with the tiles at home stuff during the last  
few days myself.

* There are 16777216 (16m) theoretical level-12 tiles.
* tiles at home has 1725217 (1.7m) level-12 tiles.
* Of those, only 28237 tiles are larger than 1000 bytes; the others  
are probably empty.
* 41852 level-12 tiles should theoretically exist, judging from OSM  
data we have.

I cannot quite explain the gap between the last two numbers, as I've  
used the distributed tile generation during the last few days to re- 
generate about 30.000 tiles which were either outdated or missing,  
and I had hoped to close that gap. I guess that many of the 41852  
tiles that have OSM data might contain data that is not rendered, so  
that a request for rendering one of these tiles results in an empty  

I'll have to investigate this because otherwise I'll continue to  
request rendering of tiles that I think must be missing, only to find  
that rendering them has no effect!

 From the work done in the previous days I can say that with the  
current participants, about 10k level-12 tiles can be rendered on  
tiles at home in one day.


Frederik Ramm  ##  eMail frederik at remote.org  ##  N49°00.09' E008°23.33'

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