[FWTools] Re: FWTools Digest, Vol 18, Issue 11

[Frank Warmerdam]

Sujoy Chaudhuri wrote:
> Hi
> 
> I'm also using 1.0.0a9 - but I found that geom.GetArea and 
> geom.GetEnvelope work really well! I dug out a post by Frank on another 
> list where he mentions that the GEOS support for distance was not 
> enabled for Windows. I wrote a simpleroutine that does the same thing 
> using great-arcs, but depending on the formula used, am producing very 
> different results - has anyone worked this one out?

Sujoy,

I am quite certain that the Distance() method in OGR (calling GEOS) does
not attempt to take great-arc distance into account.  It is a simple euclidean
distance in the coordinate system of the geometries.

If you wanted something to compare against you might look at the geod program
from the PROJ.4 distribution though I haven't used it much myself.

Best regards,
-- 
---------------------------------------+--------------------------------------
I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush    | President OSGF, http://osgeo.org