[GRASS-user] (kein Betreff)

[Patton, Eric]

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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