[GRASS-dev] Scale display in GRASS Monitor

[Hamish]

Markus Neteler wrote:
> the GRASS monitor does not show the approx. scale of the map.
> In the past I introduced that one or two times but it was
> reverted. Since every GIS shows a scale on screen, it is
> hard to explain why GRASS doesn't do it.
> 
> So I launch a new attempt to get the scale (back) on top
> of the GRASS monitor... I know about dpi and all this stuff
> but we really don't need centimeter precision :-)
> 
> Opinions?

why not a checkbox in the GUI which will overlay:
  d.barscale -l at=0,0

?  [easy]


or do you want "1:50000" in the window title. [hard]


For reasons outlined by Glynn, I am against adding "1:50000" which
would be a guess and will often be wrong. Let's not introduce known
mistakes. GpsDrive was written using such a thing and it is a horrible
hack (I worked the "magic" constant backwards, and figured the original
calculation was done on a 17" 800x600 monitor, and has been "wrong"
ever since monitors improved from those).


Also this doesn't work for lat/lon locations.

Another point worth mentioning: "ps.map scale=" (1:50000) is badly
broken for lat/lon scales, as has been for a long time.
  http://intevation.de/rt/webrt?serial_num=3096

I know Arc lets you put bogus scale bars on lat/lon maps (customers
"asked for it"..), but IMO this borders on legal liability for the
resultant fuc ups.


Martin:
> maybe a wrong idea, should be this feature part of d.barscale module?
> I wanted to rewrite this module some time ago, I would have new
> motivation to do it now...:-)

why? what do you find wrong with it?



Hamish