[OSM-talk] Vector rendering on the client?

[Frederik Ramm]

Hi,

Greg wrote:
> I think I'm on safe ground with my presumption that maps are recorded and 
> stored in vector format. 

True, but they are also automatically processed into bitmaps, which then 
get delivered to the browser.

> I observe that whan I try to _use_ the map (on 
> Firefox 3 on SuSE 10.3/Linux) it takes a looooong time to render and does so 
> in a bitmap format. 

It doesn't render the map from vectors at the time of viewing (unless 
you're talking Potlatch or the "data" layers which do, and they take a 
negligible amount of time to render compared with the time used to 
retrieve the data).

> Since my browser is able to render SVG natively (albeit a subset of the full 
> SVG spec), is there a way to offload some of the processing burden from the 
> server and retrieve maps in vector format. 

Theoretically yes, the original Osmarender is XSLT based and so runs in 
a browser. See 
http://wiki.openstreetmap.org/index.php/Osmarender_Frontend for a cool 
render-in-browser application.

However this will not make things faster because it will increase the 
strain on the database to deliver the data to be rendered, a database 
which is already under some strain. Again, there's some work done to 
improve that by tiling the existing data into parcels for quick access, 
see http://wiki.openstreetmap.org/index.php/OJW%27s_tile_data_server, 
but that's not in productive use as far as I know.

Bye
Frederik

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