[mapserver-users] doubt about mapserver URL: coordinate system

Michael Smith michael.smith at usace.army.mil
Thu Oct 7 07:50:43 EDT 2010


Sebastian,

You can use either mapserver  or wms syntax with openlayers.

The coordinates you see are in the Google Mercator or Spherical Mercator
projection. The google coordinates are the tile references (z=19) and the x
and y should match the center point of your mapext/imgext.

To use mapserver with google mercator you¹d use the projection block at the
mapfile level of

PROJECTION
 "proj=merc lon_0=0 k=1 x_0=0 y_0=0 a=6378137 b=6378137
towgs84=0,0,0,0,0,0,0 units=m no_defs"
END

Mike


-- 
Michael Smith
US Army Corps of Engineers
Remote Sensing/GIS Center
Hanover, NH 




On 10/7/10 7:42 AM, "Sebastian E. Ovide" <sebastian.ovide at gmail.com> wrote:

> you are right. Thanks
> 
> On Wed, Oct 6, 2010 at 6:15 PM, Rahkonen Jukka <Jukka.Rahkonen at mmmtike.fi>
> wrote:
>> Hi,
>> 
>> It looks like your application is calling Mapserver with native CGI requests
>> and I believe you have defined some special Mapserver layer in your
>> application. Try to change it to standard WMS layer.
>> 
>> 
>> -Jukka Rahkonen-
>> 
>> 
>> Sebastian E. Ovide wrote:
>> 
>> Lähetetty: ke 6.10.2010 18:06
>> Vastaanottaja: mapserver-users at lists.osgeo.org
>> Aihe: [mapserver-users] doubt about mapserver URL: coordinate system
>> 
>> Hi List
>> 
>> I'm using OpenLayers + MapServer. With Firebug I see that OpenLayers calls
>> MapServer with ULRs like this:
>> 
>> http://mapserver/mapserver?layers=NAFRA_2008_final
>> map=/home/gis/conf/mapserver/uk.map
>> mode=map
>> map_imagetype=png
>> mapext=-374388.56527373+7296678.7179959+-374312.12824546+7296755.1550241
>> imgext=-374388.56527373+7296678.7179959+-374312.12824546+7296755.1550241
>> map_size=256+256
>> imgx=128
>> imgy=128
>> imgxy=256+256
>> 
>> Just trying to understand the coordinate system used by mapext and imgext. (
>> it is different from than that used to call Google servers:
>> http://mt0.google.com/vt/lyrs=m@133&hl=en&src=api&x=257246&y=166679&z=19&s=G
>> )
>> 
>> Is it possible to use a different coordinate system ? say for example the
>> same coordinate system specified in the LAYER (in my case epsg:27700)
>> 
>> thanks
>> 
>> --
>> Sebastian E. Ovide
>> 
> 
> 

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