[postgis-users] [postgis-devel] Sphere or Spheroid

[Paul Ramsey]

My feeling as well, particularly when comparing the spheroid distance
to the sphere distance to the distance on a properly projected plane.
The spheroid and projected plane distances are very very close, the
sphere is as much as 0.5% off them, depending on how long a distance
you measure.

P.

On Fri, Oct 30, 2009 at 5:17 PM, Richard Greenwood
<richard.greenwood at gmail.com> wrote:
> On Fri, Oct 30, 2009 at 5:48 PM, Paragon Corporation <lr at pcorp.us> wrote:
>>
>> The choice of default sphere vs. spheroid is probably something we should
>> ask the general PostGIS users group so cc'ing them since more people
>> frequent that list that would have strong opinions on this subject.
>>
>> So question folks -- is which do you prefer as default behavior for new
>> geography data type
>>
>> faster sphere calculation (with 0.05% - 1% margin error) (I vaguely recall
>> that's what my studies suggested around the globe compared to UTM)
>>
>> or
>> slower more accurate spheroid calculation
>
> I think that the default should be to "do it right" and that "doing it
> fast" should be optional.
>
> --
> Richard Greenwood
> richard.greenwood at gmail.com
> www.greenwoodmap.com
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