[GRASS-dev] [GRASS GIS] #2714: wish: logarithmic legend for raster maps

#2714: wish: logarithmic legend for raster maps
--------------------------+---------------------------------------------
  Reporter: veroandreo | Owner: grass-dev@…
      Type: enhancement | Status: new
  Priority: normal | Milestone: 7.0.5
Component: Display | Version: svn-releasebranch70
Resolution: | Keywords: d.legend, gsoc2016, cartography
       CPU: x86-64 | Platform: All
--------------------------+---------------------------------------------

Comment (by lazaa):

Replying to [comment:13 veroandreo]:
> Replying to [comment:11 lazaa]:
> > Thanks for real data, it was much easier find the mistake. It gives
better results now.
>
> Yes, it is better indeed. But check how the scale for chlorophyll
proposed by NASA looks like (and how a logarithmic scale looks like in
general):
http://oceancolor.gsfc.nasa.gov/images/CHL_chlor_a_colorscale.png
>
> Values should be equally spaced, "graphically" speaking (for example:
0.01, 0.03, 0.1, 0.3, 1.0, 3.0, 10.0) and therefore more space in the
color palette is needed for lower values, i.e.: more space for "blues"
"cyans" and "greens" in your example (there's still a lot of red).

You're right, I used wrong formula to calculate the scale.

>
> > ...
> >
> > but maybe I should add new option so user can determine how many
digits display?
>
> This could be useful in general :slight_smile:

--
Ticket URL: <https://trac.osgeo.org/grass/ticket/2714#comment:14&gt;
GRASS GIS <https://grass.osgeo.org>