Syntax_B
Specify the coding for average Bottom Reflectance

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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
 
 
Syntax_B 
Specify the coding for Bottom Reflectance
-B/tclNe/cNorm5.00/LBref200_100/Bmin0/cLM1.00


-B/TCLne_2.5/............BSflag=1 Write a spectral TOA water-column corrected low tide view chequered
-B/TcLne_2.5/.............BSflag=2 Write a spectral TOA water-column corrected low tide view full
-B/tCLne_2.5/............ BSflag=3 Write a spectral BOA ranged 0-250 low tide view chequered
-B/tcLne_2.5/..............BSflag=4 Write a spectral BOA ranged 0-250 low tide view full
-B/tclne_2.5/...............BSflag=5 Land areas are coded 0 in spectral low tide view full 
T(t)...................write a TOA(BOA) spectral image
C(c).............Write a Chequered spectral image
L(l)...............Lands are set at Black=0
N(n).............NORMflag to "normalize" LBS
E(e).............EXTBflag to extrapolate LBS : only if SIGflag>0 in -Z... argument
            obsolete since RLBgb was introduced
_2.5 ............CoefNORM Normalization Coefficient

LBref[1]=200 max bottom brightness in imageB for the 1-band case
LBref[2]=100 max bottom brightness in imageB for the 1-band case for areas masked at 236 -like outer reef slopes

BMin =10 if B<BjMin, the pixel shall
  • either be coded DeepWater
  • or processed as the one-band case using LBref[1]
  • default is Bmin=0
cLM =1.15 coefficient applied to LM values:
  • LsM=La+(LsM-La) *CoefLM
  • default is CoefLM=1.000
  • run the -Calibrate/...
  • do not forget to
    • change for new -LsM... in the command line
    • return CoefLM to1: this is the default
      • .../cLM 1.10 is allright: this is the default

bot[1]_bot[2]_bot[3]_bot[4] is optional:
the following values are provided in 4SM_DEFAULTS anyway: 0_200_254_253