[postgis-users] degree vs. metric projection performance?

Pedro Doria Meunier pdoria at netmadeira.com
Wed Nov 26 06:11:01 PST 2008


Hi Regina :)

Could you please provide the entry for the spatial_ref_sys table for 
this SRID ?

Best regards,
Pedro Doria Meunier

Obe, Regina wrote:
>>  By the way, are the Google Mercator and WGS84 systems equivalent
>>     
>
> No they aren't.  I think Google is a mercator meter projection (not good
> for measurement though but more or less good for presentation) and they
> use WGS84 datum when accepting data.  I think it actually has an
> official SRID (could be wrong)
> that is EPSG:900913
>
> and proj4 looks like this
>
> +proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0 +y_0=0
> +k=1.0 +units=m +nadgrids=@null +no_defs
>
> People usually plot WGS84 longlat (4326) on Google Maps, thus the
> confusion.
>
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