EPSG:4326 was chosen as the "only mandatory projection" for OGC web services around 2000, five years before Google decided that not-quite-Mercator should be the new standard.
It is also "unprojected", that is the units are latitude/longitude, so projecting it only requires a forward projection, while projecting not-quite-Mercator requires both an inverse projection into latitude/longitude and then a forward projection into your desired destination. As the units are latitude/longitude on WGS84, folks can easily match them to their handy GPS unit outputs. Whether 4326 is more or less f***ed up at the poles is a matter of debate, I suppose, but at a minimum it wastes fewer pixels on the north and can be used at slightly higher latitudes. (Though storing northerly imagery in *either* 4326 or 3857 seems like a bad idea, IMO, given the distortions introduced and damage the resampling process therefore will do to the data.) So, I'd guess an answer would be: history; simplicity. All arbitrary decisions are arbitrary, but some are more arbitrary than others. P. On Mon, Nov 7, 2011 at 4:40 AM, Josh Doe <[email protected]> wrote: > I've been trying to find the discussion or rationale for why EPSG:4326 > is the projection of choice (or only supported projection?), but > haven't had any luck. It seems to me that most imagery will eventually > be consumed in EPSG:3857/900913, though of course not exclusively, so > it seems that would be a better choice. Is there any technical reasons > why EPSG:4326 is preferred, or any statistics on it being more > prevalent? I think the answer to this belongs in the docs. > > Thanks, > -Josh > > _______________________________________________ > talk mailing list > [email protected] > http://host134.hostmonster.com/mailman/listinfo/talk_openaerialmap.org > _______________________________________________ talk mailing list [email protected] http://host134.hostmonster.com/mailman/listinfo/talk_openaerialmap.org
