[OSM-dev] [Tilesathome] t at h Lowzoom implemented :-) (nearly)
80n80n at gmail.com
Tue Aug 14 09:49:11 BST 2007
On 8/14/07, spaetz <osm at sspaeth.de> wrote:
> Crossposting, as that may interest more people that jsut tiles at home.
> Using deelkar's holiday as he can't hit me with a stick now :-), I hacked
> away at the t at h client.
> - I removed hardcoded assumptions that z12 is the lowest zoom level we
> ever use in the t at h client.
> - I modified the t at h render client to fetch data from 80n's zappy API at
> low zoom levels.
> - I added initial stylesheets that can be used on z6-z11
> All that is in SVN now. As a consequence, we are able to directly render
> lowzoom tiles in osmarender with corresponding stylesheets (please don't use
> and upload with it yet, though). This implies all kind of potential
> goodness, like readable city names at low zoom levels, emphasized motorways
> and railways, County and Country names etc... Exciting, isn't it?
> Of course this is still not mature, there are 2 areas which need
> - Rather than mercator coordinates we use lat/lon. High low zooms this
> will skew things (I don't know by how much). Somebody will have to write a
> preprocessor to fix this. (not me)
I *think* it should be possible for the zappy API to provide projected
coordinates, probably like this:
<node lat='x' lon='y' mercator:lat='m' mercator:lon='n'>
Then it should be possible for Osmarender to use the projected coordinates
if they are present, or use it's own method if it isn't.
- Sea tiles are not rendered as such. (neither are coastlines it seems). I
> have no clue about that sea lookup works during the render phase, so I can't
> promise a quick fix here. Deelkar, or Frederik might know that stuff better.
> OK here are the pretty pictures :-):
> I rendered z10 and z11 of the Dover/Calais area:
> I am also currently rendering a z6 (up to z11) in the Zurich area as a
> test, which will be available here:
This looks great :D
(keep in mind that the low zoom stylesheets are not yet adapted to provide
> usefull sizes, so town names will still be tiny here...)
> my next steps:
> -Develop stylesheets further to be useful.
> -Look into sea tiles
> -Make request queueing be smart enough to see if a low-zoom renderer or a
> high-zoom renderer asks for work and enable low zoom requests.
> -Once mature enough, probably start rendering z10 and z11 directly and
> stitch lower zoom levels together from z10 for now.
> Tilesathome mailing list
> Tilesathome at openstreetmap.org
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