On Fri, Jul 31, 2009 at 3:42 PM, Tels <nospam-abuse@bloodgate.com> wrote:

On Thursday 30 July 2009 09:13:37 Daniel Kinzler wrote:
> Hi all
>
> I'm wondering if any thought has been given to rendering maps to SVG.
> I'm asking that especially in the light of
> <http://techblog.wikimedia.org/2009/07/svg-for-all-with-flash/> which
> might give use in-browser display of SVG, and perhaps even
> interactive SVG. Using that with OSM would be really cool!
>
> Now, afaik Mapnik supports SVG rendering. But I suspect that
> interactive vector maps would work differently from interactive
> pixel-based maps: you could scale smoothly, could use much bigger
> tiles, and would use level-of-detail layers instead of pre-scaled
> tiles...
>
> Does somethign like that exist yet?

I toyed around with the idea, but I think SVG would not be able to
handle a few hundred thousand objects that you get on zooming to level
11 and lower. Someone prove me wrong please :)

The trick, surely, is to filter the data at that zoom level so that you don't try to render too much.

When used with tiles@home, Osmarender renders place names for low zoom levels by working with a filtered dataset[1]. The place names are then superimposed on top of a captionless tileset that is derived by a separate process.

This link shows tiles containing just place names (major cities and countries) at zoom 5: http://informationfreeway.org/?lat=46.392704527927286&lon=9.361316960562966&zoom=5&layers=00000F00BT

You can imagine that it would be just as easy to render major features like coastlines and motorways using the same technique.

80n

[1] Providing such filtered datasets are one of the primary purposes of XAPI