Optical calibration, bathymetry, water column correction and bottom typing of shallow marine areas, using passive remote sensing imageries
4SM
Things we know
Things we don't


 
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
 
So
I keep digging
until suitable data
become available
 

Your comments are invited                            See you on 4SM blog
 
 

 

Lsw The problem with Lsw in an 8 bits image


TrustWorthy

 
   BPL The Brightest Pixels Line assumption is mostly trustworthy    1  2   3
Jerlov Jerlov's table of diffuse attenuation coefficients for downwelling irradiance is applicable to two-ways shallow water RS radiance      1  
Deglint Deglinting does a good job indeed!
It does remove sun/sky glint - and/or some adjacency effect situations
 
Panchro The panchromatic band of SPOT XS+P may be used as an extra multispectral band
 (see BoraBora      Sanaa      4SM_panchro)
 
Smoothing Smart Smoothing does a good job!  
Soil Line The Soils Line is trustworthy,  to a limited extent though: the RLBgb trick can help a lot!   

 

 

Bandset: wavelengths in nanometers

 

SPOT XS

-WL650/750/850                                                                                                                           

 

Landsat TM

-WLM518.0/610.0/693.0/905.0
-WLm452.0/529.0/624.0/776.0
-cWL00.500/0.530/0.500/0.500
-WL00485.0/571.92/658.5/840.5

Landsat ETM

-WLM513.9/600.7/692.0/898.0
-WLm441.3/519.4/630.6/771.6
-cWL???
-WL???

IKONOS

-WLM515.9/595.5/697.7/852.7
-WLm444.5/506.4/31.8/757.3
-cWL???
-WL???

QUICKBIRD

-WLM??? -WLm??? -cWL???
-WL???

WV2

-WLM/453.0/508.0/581.0/627.0/689.0/744.0/890.0/954.0
-WLm/401.0/447.0/511.0/588.0/629.0/704.0/772.0/862.0
-cWL???
-WL???

CASI

Wavelengths at mid waveband are applicable,
with some caution though in the yellow-orange region of the solar spectrum.
Using the -CP argument is a must.