[OpenLayers-Users] SphericalMercator and SRS aliases
epsg:900913, epsg:3857, epsg:3785, epsg:102113
christopher.schmidt at nokia.com
christopher.schmidt at nokia.com
Mon Jul 19 10:15:45 EDT 2010
On Jul 19, 2010, at 8:51 AM, ext Anne Blankert wrote:
>
> Hello Bart,
>
> My 2 cents:
> In my opinion it is quite difficult for users to discover:
> - OpenStreetMap, Google, Bing, Yahoo etc. use a projection called
> 'SphericalMercator'
> - 'SphericalMercator' in OpenLayers uses code 'epsg:900913'
I think this is reasonably well documented in
http://docs.openlayers.org/library/spherical_mercator.html
and if you search for:
http://docs.openlayers.org/search.html?q=google+projection
You get that as one of the results. (Not as highly ranked as I would
like, I'll admit, but it is there.)
> - there exist multiple aliases for 'epsg:900913' and some services
> prefer alias epsg:3857 or epsg:102113 over epsg:900913
> - how to override the default openlayers sphericalmercator epsg code
> with an other epsg code
This being supported is something I'd question ;) Until very recently,
I'm pretty sure it was not at all possible to do this, so it's not really
a surprised that it isn't well documented, in my opinion.
> - discover that the override produces side effects in measurement and
> mouseposition (and other functions, such as click-events...?)
> - how to solve the side effects, by adding code:
> OpenLayers.Projection.addTransform("EPSG:4326", "EPSG:3857",
> OpenLayers.Layer.SphericalMercator.projectForward);
> OpenLayers.Projection.addTransform("EPSG:3857", "EPSG:4326",
> OpenLayers.Layer.SphericalMercator.projectInverse);
>
> But instead of solving this in the library, this can also be part of the
> documentation. Maybe that documentation already exists and I've
> overlooked it?
No documentation like this exists at this time that I'm aware of.
-- Chris
>
> Cheers,
>
> Anne
>
> On 7/19/2010 1:15 PM, Bart van den Eijnden (OSGIS) wrote:
>> Hi Anne,
>>
>> check the example (first couple of lines in comments):
>>
>> http://trac.openlayers.org/browser/trunk/openlayers/examples/web-mercator.js?rev=10384
>>
>> So that's up to the application to provide (at least for now). But I can
>> also see that's not really easy for end-users.
>>
>> What do other people think about providing the EPSG aliases by default in
>> the OL library?
>
>
> _______________________________________________
> Users mailing list
> Users at openlayers.org
> http://openlayers.org/mailman/listinfo/users
Regards,
--
Christopher Schmidt
Nokia
More information about the Users
mailing list