[Tilecache] TMS question

[Josh Livni]

Guillaume,

One point to note is that while Google Earth uses tiles in epsg:4326 (or
'degrees' as you call it), Google Maps uses an entirely different and
incompatible set of tiles.  If you want to display tiles in both GE and
GMaps, you need two different sets of tiles.  TileCache could potentially
create/serve both sets up.  Or Gdal2Tiles can also create each different set
for you. But they're not the same.

 -Josh


2010/1/12 Guillaume Sueur <no-reply at neogeo-online.net>

> Thanks for this enlightment Klokan. One main point which confused me is
> the ability of a gdal2tiles mercator cache to be displayed in
> GoogleEarth. But I guess the kml does all the job.
> For Tilecache superoverlays to be usable on a 900913 cache, would it be
> enough to transform the coordinates generated in the kml overlay in
> degrees ?
>
> Best regards.
>
> Guillaume
>
> Le mardi 12 janvier 2010 à 17:33 +0100, Klokan Petr Přidal a écrit :
> > Hi Guillaume,
> >
> > You are comparing address of the tiles in Mercator (EPSG:900913) and
> > in Geodetic (EPSG:4326) TMS profiles. I guess your maptiler tiles are
> > in "mercator" profile. To set up TileCache for mercator read this post
> > from Chris:
> >
> http://crschmidt.net/blog/archives/311/using-tilecache-with-google-maps-and-virtual-earth/
> >
> > Here are same examples (proving the url is the same for both MapTiler
> > and TileCache):
> >
> > TMS "geodetic" (EPSG:4326) profile - examples:
> >
> > - http://labs.metacarta.com/wms-c/tilecache.py/1.0.0/basic/4/16/12.png
> > from http://www.tilecache.org/ website.
> > - http://staremapy.mzk.cz/naturalearth/4/16/12.png
> > from http://staremapy.mzk.cz/naturalearth/openlayers.html
> >
> > TMS "mercator" (EPSG:900913 or EPSG:3857) profile - examples:
> >
> > - http://hypercube.telascience.org/tiles/1.0.0/google-tiles/8/40/167.png
> > from http://crschmidt.net/mapping/google-tilecache.html
> > - http://www.klokan.cz/projects/gdal2tiles/overlay/8/40/167.png
> > from http://www.klokan.cz/projects/gdal2tiles/overlay/openlayers.html
> >
> > This mashup shows different tile names for mercator tiles:
> > http://www.maptiler.org/google-maps-coordinates-tile-bounds-projection/
> > TMS Mercator is the default output of gdal2tiles/maptiler.
> >
> > Best regards,
> >
> > Klokan Petr Pridal
> >
> > >> You're comparing an EPSG:4326 to a EPSG:900913 map... and thinking
> they'll
> > >> have the same tile IDs? Is that what you're asking?
> > >
> > > Did I ? My confusion must invade my postings too then !
> > > Here's what I'm trying to do exactly :
> > > I have a huge gdal2tiles cache (EPSG:4326) over France, and I retrieve
> > > the tiles from it throught standard TMS requests.
> > > I have a TileCache of a WMS layer in EPSG:4326 and I want to overlay it
> > > to the previous.
> > > I thought, kindly, that using the same TMS request (i mean z/x/y.png)
> on
> > > TC would send me back the correct tile. But it doesn't. At all.
> > > Here is my Tc layer's definition :
> > > type=WMS
> > > url=some_url
> > > layers=my_layer
> > > extension=png
> > > srs=EPSG:4326
> > > extent_type=loose
> > >
> > > I can't guess where the problems comes from...
> > >
> > > Thanks for your help
> > >
> > > Guillaume
> > >
> > >>
> > >> -- Chris
> > >>
> > >> > Regards
> > >> >
> > >> > Guillaume
> > >> >
> > >> >
> > >> > Le lundi 11 janvier 2010 à 13:33 -0500, Christopher Schmidt a écrit
> :
> > >> > > On Mon, Jan 11, 2010 at 03:42:35PM +0100, Guillaume Sueur wrote:
> > >> > > > Hi,
> > >> > > >
> > >> > > > I'm wondering about the TMS grid used in TC. The request I see
> here
> > >> > > > (
> http://labs.metacarta.com/wms-c/tilecache.py/1.0.0/basic/5/32/23.png)
> > >> > > > doesn't match with what I see there
> > >> > > >
> http://www.maptiler.org/google-maps-coordinates-tile-bounds-projection/
> > >> > > > for that area (north-east spain).
> > >> > > >
> > >> > > > Actually, does TileCache follow a specific TMS grid ?
> > >> > >
> > >> > > Not sure why you'd expect TMS and Google to be the same; Google is
> indexed
> > >> > > from the top left corner, TMS from the bottom left.
> > >> > >
> > >> > > Regards,
> > >> >
> > >> >
> > >> > _______________________________________________
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> > >> > Tilecache at openlayers.org
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> > >>
> > >
> > >
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> > >
> >
>
>
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