On 01/08/13 13:43, Nikos Alexandris wrote:
Michael:
What about just using r.rescale to rescale this?
Nikos:
Already tried (in the past) and I don't think it works from DCELL>
8-bit. It seems to chew-up (silently, as Moritz mentioned I think among
the lines in ticket #2^11) values.
It seems that "integerising" manually, in this case, is the best
approach. With the essential question remaining on "how many fine digits
should be preserved?".
Moritz:
r.rescale is just a frontend to r.reclass. and as such is meant for CELL
maps. It should'nt make a difference whether it is 8-bit or more, though.
For DCELL you can try to use r.recode.
Nikos:
Didn't work also (tried the previous days) -- I can try again.
Moritz:
Please be more precise than "didn't work"...
Right, "be more precise" is the key to "freedom" :D. Indeed, I used to say
(either in a "rules" file, or directly using "...<< EOF"
0.0:1.0:0:255
This did not work. Both stats and histogram of the recoded raster map, e.g. a
Red-Reflectance image ranging in
r.info Red_ToAR -r
min=0
max=0.774115699104528
were kinda flattened out
r.stats Red_ToAR_recoded_255
100%
0
255
Looking at the image I want to recode
r.stats Red_ToAR | head
100%
0-0.003036
0.02125-0.024286
0.024286-0.027322
0.027322-0.030357
0.030357-0.033393
0.033393-0.036429
0.036429-0.039465
0.039465-0.0425
0.0425-0.045536
0.045536-0.048572
I altered the rules file like
0.001:1.0:0:255
This works-out! Now, the recoded image is
r.recode in=Red_ToAR out=Red_ToAR_recoded_255 rules=recode_rules --o
r.stats Red_ToAR_recoded_255
100%
5
6
7
.
..
... \
....> Many values in-between
... /
..
.
195
196
197
*
And the histogram looks "nice" as well. I didn't grasp that -- from where
should I? In the manual there is only an example from int to float (however,
indeed, instructing 0.1 as the "target" min value).
There does seem to be a bug in r.recode. Your first rule set should work
if you set the -d flag. Maybe you can file a ticket ?
Moritz
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