Google maps & Mapserver projection issue

[joseolcese]

Jan,

Thanks a lot for your responses!

I still have no success getting the right tile with mapscript or even
mapserv.
I implemented a code that Ei Fujioka sent me and this is the result:

I guess I've nailed down the problem to this:

**** .map with no PROJECTION and latlon coordinates:
http://127.0.0.1/cgi-bin/mapserv?map=/mapear/map/mapNoProjection.map&mode=map&mapext=-64.171142578125+-31.419288124288343+-64.1656494140625+-31.41460027631321
This gives me an image with some data printed -> OK

**** .map with PROJECTION and latlon coordinates:
http://127.0.0.1/cgi-bin/mapserv?map=/mapear/map/mapProjection.map&mode=map&mapext=-64.171142578125+-31.419288124288343+-64.1656494140625+-31.41460027631321
This gives me an image with NO data printed -> WRONG

Only difference between mapNoProjection.map and mapProjection.map is that
the second one has:
CONFIG PROJ_LIB '/usr/local/share/proj/'
 PROJECTION
 "init=esri:54004"
 END

Now, using the code to convert coordinates to mercator meters, I got
-64.171142578125+-31.419288124288343+-64.1656494140625+-31.41460027631321
equal to:
-7143498.91542,-3665050.56612,-7142887.41919,-3664442.05663

But if I request
**** .map with PROJECTION and mercator meters coordinates:
http://127.0.0.1/cgi-bin/mapserv?map=/mapear/map/mapProjection.map&mode=map&mapext=-7143498.91542+-3665050.56612+-7142887.41919+-3664442.05663
This gives me an image with NO data printed -> WRONG

Any ideas??

Jose




Jan Hartmann wrote:
> 
> With Mapscript it's easy:
> 
> function ll2merc($lon,$lat) {
> 	$projIn = ms_newprojectionobj("proj=latlong");
> 	$projOut = ms_newprojectionobj("proj=merc");
> 	$p = ms_newpointobj();
> 	$p->setXY($lon,$lat);
> 	$p->project($projIn, $projOut);
> 	return($p);
> }
> 
> If you don't use Mapscript, you have to do the computations in 
> Javascript. There is a project to implement the Proj package in
> Javascript:
> 
> http://lists.maptools.org/pipermail/proj/2006-February/002125.html
> 
> but I have never worked with it
> 
> Jan
> 
> Jose Olcese wrote:
>> Hi Jan,
>> 
>> I really appreciate your help!. It seems that it might be the problem!.
>> I'll try sending Mercator Coordinates in meters as the mapexp parameter 
>> of mapserv.
>> 
>> Do you have the algorithm for converting it?
>> 
>> Thanks again
>> Jose
>> 
>> 
>> 
>> 
>> On 6/4/07, *Jan Hartmann* < j.l.h.hartmann at uva.nl 
>> <mailto:j.l.h.hartmann at uva.nl>> wrote:
>> 
>>     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=
>>    
>> <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);
>>      >     }
>>      > ...
>>      >
>>      >
>>      >
>> 
>> 
> 
> 

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