[Proj] Algorithms for geodesics

Charles Karney charles.karney at sri.com
Mon Jul 16 14:03:28 EST 2012

On 2012-07-16 13:47, Gerald I. Evenden wrote:
> On 07/16/2012 10:36 AM, Charles Karney wrote:
>> >On 2012-07-16 10:15, Alexander Holsteinson wrote:
>>> >>Did the guys from Google Earth ever address the problems you indicated
>>> >>to them regarding their model?
>>> >>
>> >No, I couldn't get any traction on my concerns.  Undoubtedly, they see
>> >their customers as ordinary consumers who are chiefly interested in a
>> >responsive GUI and pretty pictures and who are less interested in the
>> >precision of the data.
>> >
>> >     --Charles
>> >_______________________________________________
>> >Proj mailing list
>> >Proj at lists.maptools.org
>> >http://lists.maptools.org/mailman/listinfo/proj
> What a surprise.
> Seriously, I would be surprised if there was any other response. Google
> is not a Nat'l Geog. Society clone likely to spend hours on the technical
> minutia of cartography.

Not all of the issues are minutia...

(1) You might expect that a user should be able to draw a polygon that
encircles the north pole.  However you can't do this with Google Earth.
(Google isn't "wrapping" longitudes reasonably in this instance.)

(2) You might expect that if the documentation says that the edges of a
polygon have constant bearing that this property should hold.  It
doesn't.  (Constant bearing means straight lines on a Mercator
projection.  Instead Google Earth uses straight lines on a plate caree


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