[gdal-dev] OGRGeometry Distance

[Yilmaz Arslanoglu]

Hi Even;

Thank you very much for your help.

Regards,
Yilmaz

On Mon, Sep 21, 2009 at 9:37 PM, Even Rouault
<even.rouault at mines-paris.org> wrote:
> Selon Christopher Barker <Chris.Barker at noaa.gov>:
>
> I'd note that in the OGR XPlane driver, a function is available to compute the
> distance on the spheroid. You could use it if you don't need much accuracy :
> http://trac.osgeo.org/gdal/browser/trunk/gdal/ogr/ogrsf_frmts/xplane/ogr_xplane_geo_utils.cpp
>
> (It's an internal function to OGR, so you'd have to copy&paste it in your code,
> or add a CPL_DLL decoration in the corresponding .h and rebuild GDAL)
>
>> Yilmaz Arslanoglu wrote:
>> > I wanted to compute the distance between two points,
>>
>> you need to be clear by what you mean here: I suspect you mean:
>>
>> "The shortest distance between two points following the surface of the
>> earth"
>>
>> In which case, what you are looking for is referred to as the geodesic
>> distance:
>>
>> http://www.vterrain.org/Misc/distance.html
>>
>> To do this accurately (and you may not need much accuracy!) on an
>> ellipsoid requires a fair bit of math. I don't know if it's built in to
>> OGR or PROJ at this point, but there are a few libraries out that that
>> do it, including Gerald I. Evenden's "geodesic" lib, which can be found
>> here:
>>
>> http://home.comcast.net/~gevenden56/geodesy/project/
>>
>> -Chris
>>
>>
>>
>> --
>> Christopher Barker, Ph.D.
>> Oceanographer
>>
>> Emergency Response Division
>> NOAA/NOS/OR&R            (206) 526-6959   voice
>> 7600 Sand Point Way NE   (206) 526-6329   fax
>> Seattle, WA  98115       (206) 526-6317   main reception
>>
>> Chris.Barker at noaa.gov
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>>
>
>
>