[GRASS-user] (kein Betreff)

[Nikos Alexandris]

Just another piece of information (although don't remember where I read
it): In general every 0.0001° of latitude equals ~ 11m. Longitude I
think is the tough one... ;-)

On Thu, 2007-12-13 at 14:12 -0500, Patton, Eric wrote:
> The width of a degree of longitude varies by latitude; meridians of longitude converge to
> a single point at the poles. Latitude varies as well, although considerably less so, due to 
> the rotation of the earth slightly squashing the poles, and bulging the Equator.
> 
> ~ Eric.
> 
> 
> -----Original Message-----
> From: grass-user-bounces at lists.osgeo.org on behalf of Gerald Nelson
> Sent: Thu 12/13/2007 3:06 PM
> To: 'Nikos Alexandris'; 'Michael Misun'
> Cc: grass-user at lists.osgeo.org
> Subject: RE: [GRASS-user] (kein Betreff)
>  
> I'm curious about the statement that "Lat-Long is not good to do distance
> measurements" Someone else made a similar observation in a different
> conversation recently too. I'm not a geographer so I'm probably missing
> something but doesn't lat long just give you a point on the surface of the
> earth and if you have two of these don't you more or less automatically know
> the distance between them?
> 
> Regards, Jerry
> 
> -----Original Message-----
> From: grass-user-bounces at lists.osgeo.org
> [mailto:grass-user-bounces at lists.osgeo.org] On Behalf Of Nikos Alexandris
> Sent: Thursday, December 13, 2007 10:55 AM
> To: Michael Misun
> Cc: grass-user at lists.osgeo.org
> Subject: Re: [GRASS-user] (kein Betreff)
> 
> Lat-Long is not good to do distance measurements!
> 
> Why don't you reproject your lines in a "metric" projection system and
> check the distances again.
> 
> On Thu, 2007-12-13 at 14:03 +0100, Michael Misun wrote:
> > hello everybody!
> > i have a little problem:
> > i want to set vertices on lines in a specified space (e.g. 2 km) in a lat
> long coordinate system.
> > i tried it with "v.to.points -vi .... dmax=0.03" and it works. the problem
> is, that in the equatorial zone the space between the new added points is
> about 1,7 km but up to the polzones the spacing is rather smaller and about
> 600 m!
> > can anybody help me with this problem? a want to have an equal space for
> all vertices on my polylines
> > 
> > michael
-- 
Nikos Alexandris
.
Department of Remote Sensing & Landscape Information Systems
Faculty of Forestry & Environmental Sciences, Albert-Ludwigs-University Freiburg
.
Tel.  +49 (0) 761 203 3697 / Fax.  +49 (0) 761 203 3701 / Skype: Nikos.Alexandris
.
Address: Tennenbacher str. 4, D-79106 Freiburg i. Br., Germany
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