[OSM-dev] Cutting the planet into tiles

Frederik Ramm frederik at remote.org
Thu Dec 4 23:59:21 GMT 2008


Ben Supnik wrote:
> Number 9 was the main item I was concerned about...e.g. I can't _quite_ 
> be sure about data integrity if a node might not be present in all tiles 
> that contain ways that reference it. 

Just a memory efficiency consideration on my part; instead of having a 
variable-sized list of tiles for each node, I keep a little 3-element 
array for each node that needs to be present in more than one tile. You 
can easily increase this to, say, 100, and to have absolute integrity 
you would then simply refuse to process any way that touches more than 
100 tiles, or you can replace it with a dynamic list that will simply 
cover as many tiles as it takes.

But then again, at 1x1 degree, unless we're talking Santa Claus land, a 
way that spans more than 4 tiles would have to be tens of miles long. We 
don't want such ways anyway ;-)


Frederik Ramm  ##  eMail frederik at remote.org  ##  N49°00'09" E008°23'33"

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