[OSM-dev] How is the tile-index implemented/used?

Daniel Gilbert osmmaillst at danielgilbert.de
Thu May 14 13:54:09 BST 2009

Hi Tom, Hi Frederik,
> Basically you can ignore the complicated stuff on that wiki page - the 
> only part we did is the first bit of dividing each line of lat/lon 
> into 65536 equal parts to get to 16 bit numbers which are then 
> interleaved to get a single 32 bit tile ID value. 
Thanks for pointing this out. ;)

I plan to do the following:

 From http://download.geofabrik.de/osm/ you can download "pre-cut" 
OSM-files for a single country (at least this applies to europe). Now I 
wrote a SAX-parser for the OSM-data, which works quite well (it's 
written in Delphi, maybe one day I'll port this to Delphi Prism).  So 
it's native Win32-code. The parser writes the data into an embedded 
firebird db...

To speed up rendering and displaying, I thought about splitting the 
world into tiles, like all the well-known web-renderer do. And now it 
would be interesting to know, how the renderer determines wether a node 
or a way belongs into a tile or not.

I guess the Lat/Lon conversion you described above allows me to 
determine all the nodes which are in a special area and then create a 
tile from it. I checked out the svn and came across the quad_tiles.h. 
Seems to me as if it contains the functions I would need to do the 
conversion, doesn't it?

My goal is an easy-to-use Windows application, which requires no 
additional knowledge. Simply download the country you want, import it by 
clicking a button and be happy. Then you can search for streets, towns 
or POI in general. Might maybe help to spread the word of OSM into the 


P.S.: Hopefully this message gets posted to the mailinglist... 
Thunderbird is somehow "strange" in terms of mailinglist-usage, which 
unfortunately multiplies with the user's ignorance..

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