Arcachon tutorial : Prepare your image
the AutoCAL process in 4SM now takes care of almost everything for you

back to Arcachon tutorial           next to Calibration 1


1 - Prepare Shapefiles
  • Download
  • and place it in a 4sm_tutorial_arcachon directory
  • unzip it : you get
    • ~/4SM_tutorials/4sm_tutorial_arcachon/data/....................................arcachon-full.tif
    • ~/4SM_tutorials/4sm_tutorial_arcachon/data/....................................arcachon-full.opf
    • ~/4SM_tutorials/4sm_tutorial_arcachon/4SM.4.08.............................uptodate 4SM executable code
    • ~/4SM_tutorials/4sm_tutorial_arcachon/ for various system calls
    • ~/4SM_tutorials/Caicos/FWTools-linux-2.0.6.tar.gz...........................OpenEV
    • ~/4SM_tutorials/4sm_tutorial_arcachon..............................................various_shapfiles
    • ~/4SM_tutorials/4sm_tutorial_arcachon/ line script?
  • NOTE: 4sm.calls is missing. Shall be copied from Tarawa tutorial
cp -r ~/4SM_tutorials/4sm_tutorial_tarawa/4sm.calls .
 Raw data is stored in Arcachon/data/arcachon-full.tif
Use OpenEV to
  • Export arcachon-full.tif into arcachon-full.pix in PCIDSK format
  • Georeferencing :
    • the image is 1200 rows and 2000 lines
    • it is UTM projected, but not georeferenced
    • pixel size is 20 m
    • therefore, the origin of this image is
      • Origin_XUM=0.0 km
      • Origin_YUTM=2000*.02=40.0 km
      • FalseNorthing=FalseEasting=0 km (i.e. un-known)
  • Display : use the arcachon-full.opf project to display a FCC of arcachon-full.pix
  • Import Shapefile
    • draw a rectangular polygon to specify your area of interest
    • and save it in your work directory as 4sm_tutorial_arcachon/import.shp 
 Now you need to draw several shapefiles inside your area of interest
and save them in the work directory,
ready for use in the AutoCAL process:
  • 4sm_tutorial_arcachon/Lsw.shp
  • 4sm_tutorial_arcachon/LsM.shp
  • 4sm_tutorial_arcachon/vegetation.shp (of no use as there is no blue band)
  • There is no obvious lumps of haze or swell-modulated sea-surface glint in the NIR band of the area of interest.
    • Therefore no deglinting shall be applied 

NIR                                            RED                                              GREEN
radiances are smoothed


2 - Run the AutoCAL script 

Database structure
Learn about the command line
The AutoCAL script

Prepare the AutoCAL script
run the AutoCAL commandline
nice -20  ./4SM.4.08 -Process/06_JUL_2011  -Origin/SPT @@
-DB/arcachon/27_1_0_0/3_1/500_630/0.01_22.61/1_1 @@
-Mis/Arcachon/France/Spot/XS/NA/UTM_1_008/0.02_0.02/01_AUG_1986 @@
-MakePIX @@
-Import/data*arcachon-full/dbnc_3_0_0_0/R1200_L2000/OriginOrigin_0.0_40.0_0_0/import.shp @@
-LsM/078.8/071.2/065.2_cLM=0.450 @@
For some reason (october 2017),
the AutoCALprocess in ./4SM.4.08 does not complete the LsM_Optimizer step.
Still, please check that 
  • arcachon.pix has been created and loaded with the raw data
  • the mask mSE has  been created in channel 4
  • the calibration data text file has been created:
    • open it: gedit
The textfile autoCAL.txt is incomplete
  • ?open it : gedit autoCAL.txt
Here is the command line that should have been written:

#Following is the simplified AutoCAL CommandLine=====mBPL=2====================
nice -20  ./4SM.4.08 -Process/14_Jul_2011/06_JUL_2011  -OriginSPT @@
-DB/arcachon/27_1_0_0/3_1/500_630/0.010_22.610/1_1 @@
-Mis/Arcachon/France/Spot/XS/NA/UTM_1_008/0.020_0.020/1_AUG_1986 @@
-LS/0255.0/255.0/255.0 @@
-M/0000001/00002/00003 @@
-LsM/139.7/140.8/099.2_AutoCAL @@
-Lsw/030.4/014.2/008.0 @@
-Lw/0001.5/000.0/000.0 @@
-Lm/0001.0/001.0/255.0 @@
-Lm/0004.0/002.0/005.0 @@
-Lm/0002.0/002.0/002.0 @@
-KK1_2_0.5595/Knir4.500/mask_1 @@
-Z/MSL0.00/cZ1.000 @@
-B/tclNe/LBref135_100/Bmin110/cLM1.00 @@
@B/tclNe/Bmin0/cLM0.45 @@
@deglint/vRbaD/GlintM25.0 @@
-extract/v/mBPL2 @@
-Calibrate/v/BdSNpZg/BDh_12_13 @@


3 - The output of the AutoCAL process

Notice the system of breaking waves
The water line is ill defined

BPL pixels for the pair 1_3
Too many BPL pixels are breaking waves

BPL pixels for the pair 1_2
Too many BPL pixels are breaking waves
AutoCalibration failed
  • Too many breaking waves
    • are picked up as BPL pixels
  • ?The AutoCalibration failed
  • In order to get a clean calibration, we shall
    • ?improve the present calibration
    • perform a first modeling
    • mask the breaking waves
    • then start all over again
Green vs Red
  • this sandy formation is present as clean sands over the whole depth range:
    • as evidenced by a strong mode in the bi-dimensional histogram 
  • LsMgreen~=65 and LsMred~=60
  • ?the slope of this mode Kgreen/Kred is  ~=0.50
Green-Red vs NIR
  • LsMNIR~=60
  • There are no clouds in this scene
  • Wave breakers are abundant
    • ?see that they display just like if they were clouds
    • they must be masked out


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