[GRASS5] Re: [GRASSLIST:386] Re: Legends

[Helena Mitasova]

H Bowman wrote:
> 
> Hi --
> 
> Due to popular request, I've modified the d.legend range= option to
> extend to the limits given in the colr file, if it exists.
> 
> This will allow a user to copy a standard colr file to many rasters and
> have the same legend display regardless of the actual data extent. Some
> remote sensing applications where this might be useful are for frames of
> a SST animation or display of 0-255 ranged color channel data.

I hope that I understand this option correctly, if yes then
another useful application is time series of data either from 
monitoring or simulations, where e.g. for water I use the same color
table
for all time steps although at the beginning of the simulation the range
of data 
is much smaller. It is even more useful when comparing results of
simulations
(e.g. erosion) for different scenarios, by using the same color table
and same legend for all results you quickly see which one produce much
less 
erosion than the maximum.

So I consider this option really useful and I hope that it does not
broke anything
and does not cause some unexpected problems.

thank you for working on legends - it has made a whole world of
difference for my work,

Helena
> 
> While this works pretty well, I'm still not 100% convinced it's a good
> idea. My main problem with it is conceptual: that d.legend isn't purely
> a child of the raster data anymore.
> 
> If somebody wants to mis-represent a what's in a plot, I think they
> should have to do it explicitly with the legend taken from a second
> raster, and not by oversight. I've put in a Warning message, but I'm
> still not totally happy about it.
> 
> My second problem is I'm not sure how it will interact with the
> still-not-committed use= option, which takes precedence. It requires
> some think, but probably will be ok.
> 
> anyway, here it is. The diff is versus today's CVS HEAD.
> 
> http://bambi.otago.ac.nz/hamish/main.c.withCOLR
> http://bambi.otago.ac.nz/hamish/d_legend_main_c.diff
> 
> and here's use= if you want to try it (without the colr change).
> http://bambi.otago.ac.nz/hamish/main.c.withUSE11
> 
> let me know what you think.
> 
> Hamish