This was the command line used in the process: "i.atcorr -o
iimg=L5181040_04020111020_B30_TOA@bug_2 icnd=input_grass_6.txt
oimg=L5181040_04020111020_B30_TOA_iatcorr".
i.atcor produces NULLs and strange output also for other sensors:
I can confirm this for RapidEye data:
Input Data: L3A RapidEye data without notable clouds and no blackfill.
Bands used: bed / green / blue
As RapidEye data comes in 16bit, the input data was initially rescaled to
8bit [0-255]. The results were unexpected: Only three category values:
Many zeroes and a few "1" and "2" values. This applied for all three
bands.
In a next attempt, the original 16bit data was fed into i.atcorr. The
results are described below. This was compared with a shifting (r.rescale)
of the 16 bit value ranges of all bands to start with the value "0"
[Example: original range: [4068-56975] (range: 52907) -> new range: [0 -
52907]]. The results from both kinds of input are similar:
**For the red band, a reasonable result was produced.**
Statistics of red band (digital numbers) [r.univar]:
n=49000000
null_cells=25249370
cells=74249370
min=1286
max=58603
range=57317
mean=4733.57011167347
mean_of_abs=4733.57011167347
stddev=1226.24474903503
variance=1503676.18453598
coeff_var=25.905283329616
sum=231944935472
** For the green band, a NULL layer was produced. **
Statistics of green band (digital numbers) [r.univar]:
n=49000000
null_cells=25249370
cells=74249370
min=2464
max=54248
range=51784
mean=5646.62104434694
mean_of_abs=5646.62104434694
stddev=986.535495533873
variance=973252.283948265
coeff_var=17.471253831024
sum=276684431173
** For the blue band, faulty values (looked like a binary image of the
original scene) were produced. **
Statistics of blue band (digital numbers) [r.univar]:
n=49000000
null_cells=25249370
cells=74249370
min=4068
max=56975
range=52907
mean=6479.12217332653
mean_of_abs=6479.12217332653
stddev=859.459951841108
variance=738671.408818719
coeff_var=13.2650678417419
sum=317476986493
The same data sets as described in my previous comment were used
(Spearfish AOI, 2 L3A tiles, no blackfill).
The three bands red,green,blue were all processed by the controll files
applicable for RapidEye-red/green/blue (i.e. each band was processed three
times times, once with the control file intended for it, and also with the
to other control files).
Output: Reasonable results for red and green band, blue band produces
stark black and white image.
--------------------------------------
Control File "Green":