Tarawa, Kiribati,  is a 30 km wide
in the eastern equatorial Pacific. 
SPOT XS image, 1986


We shall use a 650*600 subset 
inside the white polygon: 
please note that a heavy sky glint
is evidenced by the enhancement.

An introduction to 4SM modeling  
 return to 4SM tutorials                         Om symbol.svg                             continued  

1 - NO NEED for field data, nor for atmospheric correction
2 - this is demonstrated in this website, using a variety of hyper/multi spectral data
Requirements are
1 - homogeneous water body and atmosphere
2 - some coverage of optically deep water
3 - some coverage of dry land
Problems are
1 - the precision on estimated depth is found wanting, because the noise-equivalent change in radiance  of accessible data is too high for shallow water column correction work 
2 - radiance data should be preprocessed by the provider at level 1 in order to improve S/N ratio
3 - exponential decay: the deeper/darker the bottom, the poorer the performances
I keep digging
until suitable data
become available
The flow chart of this tutorial
  • Prepare your image                                               Line 1
    • Prepare shapefiles
    • Prepare your database
    • Prepare the AutoCAL script
    • Run the AutoCAL script
    • About the marine/land segmentation of the image
  • Investigate your image
    • About the PATH in OpenEV projects
    • Learn from your image, and segment it
    • Sample your image: the -DN... tool
    • Inspect the result of the AutoCAL process
Work on the full image   of Tarawa atoll.
Don't be mistaken:   it's really worth consolidating tour training
Install your workstation
Ubuntu 16 LTS 32 bitsUbuntu 18 LTS 64 bits
You choose

32 bits Ubuntu 16 LTS
Install your 32 bits Ubuntu Linux 4SM workstation

As of April 2018, my environment is:
ASUS ROG STRIX 17" laptop  with Windows 10
Oracle VirtualBox (4 cores, 4 GB RAM)
Ubuntu 14 LTS virtual 32 bits machine

I used  FWTools-linux-2.0.6.tar.gz 
to install OpenEV as directed in
Not any additional or proprietary driver.
No -h option to launch OpenEV.
Then I upgraded my virtual machine to Ubuntu 16 LTS,
which is supported until 2021.
64 bits Ubuntu 18 LTS

provides OpenEV on a 64 bits Linux install
see a tutorial using GuidosToolBox by Fabio Favoretto

My environment 


alias openev=" openev &"
alias dir="   ls -l    -k --color "
alias dirw="      ls -l    -k --color; pwd "
alias dira="      ls -l -a -k --color ; dir *sh"
alias dirs="      ls    -a -k --color "
alias cpr="       bzip2 "
alias ucp="       bunzip2 "
alias zip="        zip -r "
alias te="         gedit "
alias mv="        mv -i  "
alias cp="         cp -i  "
alias rm="        rm -i  "
alias gimp="    gimp &"

#home2: to mount my main disk shared file as home2
alias home2mount=" sudo mount -t vboxsf home2   ~/home2; dir ~/home2"

#sudo ln -s /media/sf_home2            home2

#sudo ln -s /media/sf_home2            home2
sudo ln -s /media/sf_Hoata1Drive    home2
please, launch "4SM.8.07", see what happens

or FWTools  ??
  • For launching OpenEV, 
    • 4SM now tests automatically the above two paths
    • whichever is installed/available shall be used
  • It requires FWTools or GUIDOS TB installed in /home directory
Please trash any previous 4SM executable and Tarawa tutorial material.
Please download the latest  
tarawa-tutorial zipfile
Unzip it as ~/4sm_tutorial_tarawa

Export data to PCIDSK image format  
 video LINE_1
  • cd ~/4sm_tutorial_tarawa/data
  • launch OpenEV
  • in OpenEV: File/Export tarawa-full.tif into tarawa-full.pix in PCIDSK format
  • in OpenEV: Image/Compose/LoadFile to display a false color composite of tarawa-full.pix 
4SM is a 32 bits binary: must be made executable 
Idem for system calls
4SM checks that they are all working fine
  • cd ~/4sm_tutorial_tarawa   
  • chmod a+x      ./4sm.calls/*     ./4SM.8.07  
  • launch    ./4SM.8.07
    • 4SM shall check that all are working fine             


Set your script tarawa-subset.sh
do as directed below
Reference script
for a reference, a full copy of my script is available:   tarawa-subset-tutorial-script-txt
update your command line script
Ensure you have one antislash 
at the end of each sub-line
If your script gets messed up, or you lost control
next get acquainted with your working database

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