[Geoprisma-users] 900913 to 4326

[Julien-Samuel Lacroix]

Hi,

I didn't test it, but I would assume that since you set your OL layer to 
4326, then it's OL that reprojction everything to 900913.

It's always better to reproject everything in the coord system you will 
use on the web.

Julien

Yves Moisan wrote:
> Hi List,
> 
> This is more of an openlayers question, but I gather OL can transform
> from/to 900913 to 4326.  I know there is 'projection' and
> 'displayProjection' and I also saw functions forwardMercator and
> inverseMercator in the OL API, but I wonder how it all fits in the
> context of geoprisma.
> 
> Say I have a mapfile that points to a 4326 dataset :
> 
> LAYER
>   NAME         aeropuertos
>   TYPE         POINT
>   DEBUG 5
> # My data's native projection
>   PROJECTION
>       "init=epsg:4326"
>   END
> ...
> 
> In the MAP section of the mapfile, I set :
> 
> WEB
>     ...                   
>     METADATA
>       ...
>       "wms_srs"  "EPSG:4326 EPSG:900913"
> ...
>     END  # Metadata
> 
> which means the two projections are dealt with in the context of the
> mapfile, from what I gather.
> 
> In the GeoPrisma config :
> 
> <map>
> <name>DefaultMap</name>
> <options>
>     <units>m</units>
>     <projection>EPSG:900913</projection>
>     <maxextent>-20037508,-20037508,20037508,20037508.34</maxextent>
>     <displayprojection>EPSG:4326</displayprojection>
> 	...
> 
> <layer>
>     ...
>     <servicetype>wms</servicetype>
>     <options>
>         ...
>         <projection>EPSG:4326</projection>
>         ...
>     </options>
> </layer>
> 
> The question is : by virtue of my mentioning the two coordinate systems
> in the WEB section of the mapfile and on the geoprisma side by setting
> the projection of the map to 900913 and that of the layer to 4326, does
> my vector layer data get automagically reprojected to 900913 by OL ?  
> 
> Or am I better off to set a projection object for the MAP to 900913 (and
> change the EXTENT and UNITS accordingly) and use EPSG:900913 in my
> <layer> object ?
> 
> TIA,
> 
> Yves
> 
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> 

-- 
Julien-Samuel Lacroix
Mapgears
http://www.mapgears.com/