[Tilecache] Seeding map images

[Evandro Dugnani]

Hi Christopher,

  I'll try to explain better...
  I have a system running here using Postgres (my map database),
Geoserver (my map image generator), Tilecache (map image caching) and
Openlayers (on my web pages). Everything works fine, and I use
projection 4326 for all images generated.
  Based in this system, I must do following: build an image cache
directory tree to use it in a standalone application. But this
standalone application will use some functions to transform a lon/lat
coordinate in a x,y refering a map image. And these functions
transform a lon,lat in a x,y the same way Google do this
transformation.
  So, I adjusted my system to generate images using projection 900913,
and changed the seeding scripts to build image cache directory as
"layer/zoom/y/x.png" (I did the change on Cache.py file), eliminating
intermediate directory levels generated by scripts by default (I
generate the images using the command "python Client.py
'http://My_tilecache.py_location?' layer zoom_level_from zoom_level_to
 bottom_left_lon,bottom_left_lat,top_right_lon,top_right_lat").
  Now, if I compare images generated (tiles) in my modified system
(scripts python) they are same as Google tiles (using Google maps to
compare images, for example). But the "y" coordinate generated by
Tilecache is not equal to Google "y" coordinate (the "x" coordinate is
the same), and I didn't find the transformation do make "y" generated
equals to Google "y" coordinate. And that is my question now, if
anybody knows how to transform "y" Tilecache coordinate to make it
equals to Google's one.
  (I don't know if I could clarify the situation or not... :-P )

  Regards,

Evandro

On Nov 7, 2007 5:16 PM, Christopher Schmidt <crschmidt at metacarta.com> wrote:
> On Wed, Nov 07, 2007 at 03:37:00PM -0300, Evandro Dugnani wrote:
> > Hi Christopher,
> >
> > > 1. TMS is bottom to top, Google is top to bottom.
> > >    tms_type=google in your TileCache config will change TileCache's
> > >    order but....
> >
> >   I'm using WMS... doesn't "tms_type=google" to be used only with TMS ?
> I must be conused. The first thing you said was:
>
> > > >   One more question... I changed Tilecache's seeding scripts to save
> > > > images in form "zoomlevel/y/x.png", as Google do.
>
> Can you explain what you mean? The TileCache seeding code doesn't save
> the tiles at all, but TileCache can be used directly as an endpoint to
> access Google like tiles. I realize now this is probably what you are
> doing. If this is the case, then you should probably read the TileCache
> code to figure out how to do what you want.
>
> Regards,
> --
> Christopher Schmidt
> MetaCarta
>