[OSM-dev] WMS-C implementation on the way (was: Status of the WMS interface?)

Immanuel Scholz immanuel.scholz at gmx.de
Fri Mar 31 08:46:49 BST 2006


Hi,

> Connected to this is an attempt to solidify the scheme for a
> distributed WMS tile cache that's been floating in the geosphere for a
> year: http://wiki.osgeo.org/index.php/WMS_Tile_Caching

Cool. Without knowing this, I came up with almost the same idea. Currently
I try to implement almost exactly this but:

- Mercator instead of EPSG:4326. This is because the OSM-Applet is using
Mercator. The disadvantage is, that I have to handle some problems with
rounding because of the translation. Oh, and that the poles cannot be
rendered of course ;-)

- The highest zoom=0 is 360 degree in east-west and about 180 degree in
south north. Projected, this is the earth squared in Mercator ;)

- Tile size is fixed to 256x256 (maybe I should change this to 512x512 to
match Mikels landsat code a bit more?)

- Because of the rounding issue, you can either get the tile by specifying
a bounding box or (better) by specifying the tile-id, while I use the
id-algorithm presented some weeks ago (except that the id became a 32-bit
integer instead of a string). This way, I think the url can be made really
static. :-)


Comments?

Ciao, Imi.






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