[OSM-dev] Simplified street-network

[Andy Deakin]

>> Hello everyone,
>>
>> did anyone else ever work on simplifying the polylines for
>> low zoom -rendering or similar purposes?
>> Any algorithms, websites or books that may help me?
>>     
>
> There's been a small amount of work on this in mapnik-rendering
> circles, but mainly using postgis' simplify(linestring, integer)
> function. I don't have info from anyone who's looked into it further
> from an algorithm point of view.
>   

Check out the google maps encoded polylines or vertex reduction algorithms.
I (and many others) have written algorithms to say which levels a 
polyline point should be visible at on google maps.

e.g. (not mine!)
http://facstaff.unca.edu/mcmcclur/GoogleMaps/EncodePolyline/algorithm.html