[GRASS-user] Re: Values from multiple raster -

[Daniel Victoria]

It's not r.mapcalc fault. I imagine it's probably a limitation due to
the number of bits in your image.  For instance, 8 bit images can have
up to 256 values. 16 bit images can have 65,535. So, if you have too
many values, you will have problems. Not sure how to avoid this in
your case but, maybe you will need to work with categories after all.
Are you planing on doing any math operations in the concatenated
values or is it more for displaying pourposes?

Cheers
Daniel


http://en.wikipedia.org/wiki/Integer_(computer_science)

On Tue, Nov 23, 2010 at 4:34 PM, Gabriele N. <gis.gn at libero.it> wrote:
>
> I have a new problem, this time I would like to concatenate two maps A and B.
> A is with 8 digits, B is with 4 digits. So I do as usual:
>
> r.mapcalc "output" = "((" A "* 10000) (" B "))"
>
> But I get strange values with negative values. I did several tests but
> without resolve. Perhaps r.mapcalc may have problems with numbers greater
> than 10 digits
>
>
> Thanks
>
> Gabriele
> --
> View this message in context: http://osgeo-org.1803224.n2.nabble.com/Values-from-multiple-raster-to-link-together-tp5741032p5767794.html
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