Google maps & Mapserver projection issue
joseolcese
jolcese at GMAIL.COM
Wed Jun 6 16:23:04 EDT 2007
Jan,
The problem was that I needed to specify PROJECTION both at the MAP and at
the LAYER level.
So, I had to specify PROJECTION "init=esri:54004" at the MAP level so it's
rendered with this projection and PROJECTION "init=epsg:4326" at the LAYER
level (because the data is in this projection).
Special thanks to Ei Fugioka who find the issue.
Thanks a lot!
Jose
Jan Hartmann wrote:
>
> Hi Jose,
>
> I think mapext must have two negative and two postive values (you
> specify four negative values):
>
> mapext=-7143498.91542+-3665050.56612+7142887.41919+3664442.05663
>
> Does this work?
>
> Jan
>
> joseolcese wrote:
>> 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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