Google maps & Mapserver projection issue

[Jan Hartmann]

Hi Jose

Epsg 54004 is the classic Mercator projection. The units it uses are not 
degrees but meters (only at the equator these are real meters). Using 
proj I get the following boundary values (note that -180W/-90S and 
180E/90N cannot be represented in a Mercator projection):

proj +init=epsg:54004
-170 -80
-18924313.43    -15496570.74
170 80
18924313.43     15496570.74

Hope this helps,

Jan

Dr. J. Hartmann
Department of Geography
University of Amsterdam

joseolcese wrote:
> Hi 
> 
> I'm trying to use Google maps & Mapserver with partial success...
> I have a .shp configured in mapserver and I can get a transparent tile from
> an html page where it load google satellite view and my tiles.
> The problem is that I wasn't using any projection on my .map so every tile
> was a little distorted.
> I added the epsg:54004 project to the .map but now the tiles are empty.
> 
> Do you have any idea why this my be happening?
> 
> Thanks
> Jose Olcese
> 
> .map:
>  IMAGETYPE      PNG
>  EXTENT           -64.20 -31.41 -64.19 -31.40
>  SIZE               256 256
>  SHAPEPATH      '/ms4w/apps/tutorial/data_jose'
>  FONTSET         '/ms4w/apps/tutorial/fonts/fonts.list'
>  TRANSPARENT  ON
>  CONFIG PROJ_LIB '/var/www/html/share/proj/'
>  PROJECTION
>  "init=esri:54004"
>  END
>   LAYER
> ...
> ...
> 
> 
> .html:
> ...
> ...
>         tileCountry.getTileUrl=function(xy,zoom)
>         {
>             var lng = (-180+((xy.x+0.5)*(360/Math.pow(2,zoom)))); // -180
> +180
> 
>             var merclat_extent = 360/Math.pow(2,zoom);
>             var l = 180 - ((xy.y+0.5) * merclat_extent);
>             var e = Math.exp(2 * ( l * Math.PI) /180);
>             e = (e - 1)/(e + 1);
>             var lat = (Math.atan2(e, Math.sqrt(1 - (e * e))) *180 /
> Math.PI);
> 
>             return
> 'http://127.0.0.1/cgi-bin/mapserv?map=/ms4w/apps/tutorial/htdocs/map_test5.map&mode=map&mapxy='
> + lng + '+' + lat + '&buffer=' + ((360/Math.pow(2,zoom))/2);
>     }
> ...
> 
> 
>