[GRASS-user] i.atcorr: Returns empty raster

Abhishek Manandhar abhishek.adams at gmail.com
Wed Mar 16 09:09:14 PDT 2016


Hello all,
I am using i.atcorr module of GRASS 7.0.4 release. I compiled the release,
as I wanted to add the Sentinel-2 sensor. So far, I was successful in
compiling the release. However, when I run atcorr, I get an empty raster
file. I have included the reports from r.info, i.atcorr and the parameters
below:

*r.info <http://r.info> output of the image*

(Wed Mar 16 16:38:39 2016)

r.info
map=S2A_OPER_MSI_L1C_TL_EPA__20160315T065417_A000920_T32TPS_B02 at PERMANENT
 +----------------------------------------------------------------------------+
 | Map:      S2A_OPER_MSI_L1C_TL_EPA__2016  Date: Wed Mar 16 16:29:33 2016
   |
 | Mapset:   PERMANENT                      Login of Creator: abheeman
   |
 | Location: munich
  |
 | DataBase: /media/abheeman/data/grassdata
  |
 | Title:     ( S2A_OPER_MSI_L1C_TL_EPA__20160315T065417_A000920_T32TPS_B02
) |
 | Timestamp: none
   |
 |----------------------------------------------------------------------------|
 |
   |
 |   Type of Map:  raster               Number of Categories: 0
  |
 |   Data Type:    CELL
  |
 |   Rows:         10980
   |
 |   Columns:      10980
   |
 |   Total Cells:  120560400
   |
 |        Projection: UTM (zone 32)
  |
 |            N:    5200020    S:    5090220   Res:    10
  |
 |            E:     709800    W:     600000   Res:    10
  |
 |   Range of data:    min = 0  max = *23562*
    |
 |
   |
 |   Data Description:
   |
 |    generated by r.in.gdal
   |
 |
   |
 |   Comments:
   |
 |    r.in.gdal -e input="/media/abheeman/data/grassdata/S2A_OPER_PRD_MSIL\
  |
 |    1C_PDMC_20160315T115050_R065_V20150826T102655_20150826T102655.SAFE/G\
  |
 |    RANULE/S2A_OPER_MSI_L1C_TL_EPA__20160315T065417_A000920_T32TPS_N02.0\
  |
 |    1/IMG_DATA/S2A_OPER_MSI_L1C_TL_EPA__20160315T065417_A000920_T32TPS_B\
  |
 |    02.jp2" output="S2A_OPER_MSI_L1C_TL_EPA__20160315T065417_A000920_T32\
  |
 |    TPS_B02" memory=300 offset=0
   |
 |
   |
 +----------------------------------------------------------------------------+
(Wed Mar 16 16:38:39 2016) Command finished (0 sec)


*i.atcorr verbose return*

(Wed Mar 16 16:39:48 2016)

i.atcorr -i -r --overwrite --verbose
input=S2A_OPER_MSI_L1C_TL_EPA__20160315T065417_A000920_T32TPS_B02 at PERMANENT
range=0,10000 parameters=/media/abheeman/data/grassdata/conf
output=munich_test_atcorr
* ****************************** 6s version 4.2b
****************************** *
*                        geometrical conditions identity
*
*                        -------------------------------
*
*                        Sentinel 2  observation
*
*
*
*    month: 8 day: 26
*
*    solar zenith angle:   39.16 deg  solar azimuthal angle: 161.21 deg
*
*    view zenith angle:     0.00 deg  view azimuthal angle:0.00 deg
*
*    scattering angle:    140.84 deg  azimuthal angle difference: 161.21
deg
*
*
*
*                        atmospheric model description
*
*                        -----------------------------
*
*            atmospheric model identity :
*
*                tropical            (uh2o=4.12g/cm2,uo3=.247cm-atm)

*
*
*
*            aerosols type identity :
*
*                    Continental aerosols model
*
*
*
*            optical condition identity :
*
*                 visibility :   13.00 km  opt. thick. 550nm:   0.3516

*
*
*
*                        spectral condition
*
*                        ------------------
*
*            sentinel_2 band1
*
*                value of filter function :
*
*                 wl inf=    0.300 mic   wl sup=    2.600mic

*
*
*
*                        target type
*
*                        -----------
*
*            homogeneous ground
*
*              constant reflectance over the spectra 0.000
*
*
*
*                        target elevation description
*
*                        ----------------------------
*
*            ground pressure  [mb]        954.77
*
*            ground altitude  [km]        0.520
*
*                 gaseous content at target level:
*
*                 uh2o=    3.227 g/cm2        uo3=    0.246 cm-atm

*
*
*
*                         atmospheric correction activated
*
*                         --------------------------------
*
Atmospheric correction...
Atmospheric correction complete.
(Wed Mar 16 16:39:59 2016) Command finished (10 sec)


*Parameters used*

20                            - geometrical conditions=Sentinel-2
08 26 10.48 11.353693 48.200905 - month day hh.ddd longitude latitude
("hh.ddd" is in decimal hours GMT)
1                            - atmospheric mode=tropical
1                            - aerosols model=continental
13                           - visibility [km] (aerosol model concentration)
-0.520                       - mean target elevation above sea level [km]
(here 600m asl)
-786                        - sensor height (here, sensor on board a
satellite)
129                           - 1nd band of Sentinel-2A


*Note*
Before I invest more time in finding process to derive correct AOT and
chose appropriate atmospheric model, I wanted to give it a try with fake
parameters. As far as I understand, with fake parameter there should be
some short of false atmospheric correction. Therefore, there are false
values for atmospheric mode, aerosol model and visibility just for test
purpose.
*From r.info <http://r.info>, maximum value seems to be 23562. But the
value in sentinel bands can range only between 0-10000 currently, which
brings to the assumption that it probably could be noise. Will it affect
the result?*

*Some general questions:*

   1. *For 6s parameter, it take geographic coordinate (I guess EPSG:4326)
   as input. So, I was wondering if we also have transform the coordinate
   system of the image to the same?*
   2. *In my system, it took 10 seconds to process one image. But, I am not
   sure if the processing time will remain same when the process outputs
   non-empty file. My image size is 10980x10980 pixels. What is general
   processing time it generally takes, for may be single Landsat-8 image ?*
   3. *Regarding the raster with empty output, does anybody have
   experienced such behavior recently? The discussions I searched mostly date
   back to the time when Landsat-8 was not supported.*


If it helps, I am running grass in the computer with Ubuntu 14.04 system,
with 8 cores,16 gb ram and Intel Core i7-4790.

Regards,
Abhishek
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