[postgis-users] WGS84 to meters

[David William Bitner]

Willy,

Yes it would be great if PostGIS natively dealt with Geodetic measurements.
This has been on many peoples wish lists for a long time.  Unfortunately,
just because something is desired does not mean that there is either a
developer "with the itch" or someone with funding.  As such a few of the
simple cases for dealing with spherical calculations have been knocked off
such as distance and length.  If this is somethat is very valuable too you,
perhaps you might want to look into funding some of the work involved.

David

On Tue, Sep 9, 2008 at 4:43 AM, Willy-Bas Loos <willybas at gmail.com> wrote:

>
> >A global equal-area projection would
>> >be better, in that you can use the same parameters regardless of where
>> >on the globe you're working.  I have a similar application, and use
>> >Cylindrical Equal Area.  I use something like (with an old version of
>> >PostGIS -- I think the function names all start with ST_ now):
>> >
>> >select sum(area(transform(glacier_polys,32767)))  FROM glacier_polygons
>> ...
>>
>>
> cool,thanks.
> distance sphere is also working great.
> I see that there is also an ST_length_spheroidI(nice, though .._sphere is
> missing).
>
> I know how to calculate distances now, but for area calculation or
> buffering i still have to transform to a different coordinate system.
> Using a single coordinate system for the whole globe is already a great
> improvement, but i still have to be cautious to use the right transformation
> for the calculation that i want to do.
>
> Wouldn't it be great if GEOS (i mean postgis really) could do calculations
> for WGS84 (which would store anything "lossless") in meters?
> We can already compute distances in meters, so why can't we do all
> calculations (area, buffer) in WGS84 ??
>
> As for buffers, it should be possible to make a buffer_sphere and a
> buffer_spheroid, because distance calculations is all it takes (afaik).
> If someone would invent a way to create an "area_sphere" and
> "area_spheroid", i would see no more need to store geometries in anything
> else than WGS84.
>
> Any thoughts on that?
>
> Cheers,
>
> WBL
>
>
>
>
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>


-- 
************************************
David William Bitner
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