Syntax_Lm
Specify the Minimum Shallow Water BOA Radiance

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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
 
 
Lm
threshold on normalized bottom contrast Ls-Lsw

-Lm0001.0/000.5/004.p/0255
  • For a solution by band j,
    • any pixel which exhibits normalized bottom contrast Lr=(Ls-Lsw)
    • less than threshold Lm in band j
    • is considered too faint for modeling: it is declared optically deep
  • All Lm values must be >0 
  • May be specified in real number like 2.3
Lm=255
Lm can be specified to 255 
to disable totally any particular band solution
  • SIG: this is not compatible with the SIG trick though, in the -Z argument
  • SIG: for SIG to operate as desired, please make Lm<=10 for bands bm[1] to FirstSIG
  • FirstSIG: see Syntax_Z
p (optional)
For progressive dynamic setting of Lm: 
darker pixel are assigned a higher Lm value
  • this combats electronic noise or faint turbidity
  • progressive Lm is no less than original Lm/4, but increases as Lr[cKMin] decreases 
  • for example, see its effect in progressive_Lm, with -Lm0001.0/004.p/008.p/00005