[GRASS5] [bug #939] (grass) d.barscale ignores PROJ_UNITS

[Eric G. Miller]

On Sun, Mar 03, 2002 at 11:58:11PM +0000, Glynn Clements wrote:
> 
> Helena wrote:
> 
> > I believe that the error was only in the untis that it has written
> > out - so everything should have stayed the same except it should
> > have written ft insted of m. So I had a barscale showing 5000m but
> > its length was in fact 5000ft. So looking into PROJ_UNITS and
> > choosing whether to write ft or m should be the fix.
> 
> So, if the "meters" setting in PROJ_UNITS is approximately equal to
> 0.3048, d.barscale should use multiples of feet, otherwise use metres? 

Ideally, d.barscale should generate scale bars in a number of units,
which the user may specify.  That is, my map units may be meters, but
folks in the U.S. often want feet/yard/mile scales.  Or, I might want a
barscale showing both kilometers and miles.  It might be nice to
allow the user to specify the number of divisions, and the division
sizes (e.g. divisions=4 divsize=10 units=miles).  Gives the user a bit
more flexibility...

> While we're on the subject of units, I note that GRASS' "foot"
> (according to src/libes/gis/proj3.c) is the international foot
> (0.3048m) rather than the US survey foot (0.3048006096m). Is this
> correct? It isn't likely to be a problem for measurements (the
> difference being 2 ppm), but it could be a significant problem for
> coordinates.

Yea, I think that's incorrect.  It should be using the "old" survey
foot.

-- 
Eric G. Miller <egm2 at jps.net>