[GRASS-user] RE:How to find shortest distances from the investigation point to the shoreline

[SGW00412 at nifty.com]

Dear Hamish and Milton:

Thank you good advice and kind message.

I intend to install (compile) a new version, 6.3 or more.

Best

Yasuo shimada
------
Hamish <hamish_b at yahoo.com>さん：
> 
> sgw00412 wrote:
> > I tested by two kinds of geographical coordinate systems by
> > using the same data.
> > 
> > One of the geographical coordinate systems is UTM54, and
> > the remainder is wgs84. 
> > 
> > data :point vector data (10 points) and a line vector data
> > OS: grass 6.2.3 on Cygwin.
> > 
> > As a result, the case of UTM54 obtained the distance of meter.
> > On the other hand, wgs84 obtained the distance of decimal value.
> > 
> > So, I guess that the decimal value of wgs84 is a degree of
> > latitude longitude.
> >  
> > 
> > Grass manual wrote that "...In lat-long locations v.distance gives
> > distances (dist and to_along) in meters not in degrees calculated as
> > geodesic distances on a sphere.."
> > http://www.ces.iisc.ernet.in/grass/grass64/manuals/html64_user/v.distance.html
> > 
> > Though this manual is version 6.4, the manual of version
> > 6.2 is not written it.
> > 
> > Is this interpretation correct?
> > 
> > If it is so, please teach me the method of converting the
> > decimal value into the meter. 
> 
> 
> Yes, version 6.2.3 is giving distances in (useless) degree units. This
> was fixed in Jan 2008 by Martin to use geodesic distance in meters, so
> GRASS 6.3.0 and the upcoming 6.4 do return meters. But 6.2.3 was
> released in Nov 2007 and so is too old to have that fix.
> 
> 
> Hamish
> 
> 
> 
>