Specify one -or a series of- shallow water Calibration Pixel for the BPL model
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 HowTo CP
Calibration pixels are used to specify a stratified water structure 

  • -CP/160.32/98.62/013.82_0.75m
    • upon calibration, a choice of CP arguments is proposed on screen
  • Linear BPL model: one shallow calibration pixel is optional
    • If no -CP... argument is specified, the -KK... argument provides the  ratio Ki/Kj for bands i and j.
    • If a -CP... argument is specified, the slope Ki/Kj of the BPL model for each pair of bands i and j in the linearized scatter plot is made to be the ratio which is specified through -LsM and -CP argument(s).
    • Ki/Kj=(log(LsMi-Lswi)-log(CPi-Lswi))/(log(LsMj-Lswj)-log(CPj-Lswj))
    • this overrides the value for the ratio Ki/Kj which is specified in the -KK... argument
  • Curved BPL model: for specifying optically stratified waters, several -CP arguments may be defined in the commandline,
    • they must appear in order of increasing depth
    •  this specifies a curved BPL model -actually a broken BPL model
  • If a radiance is too close to Lsw, best is to set it at 00.00

Stratified waters at Bahia San Basilio
observed for the Blue/Green pair of bands
in a Landsat 8 image aquired on October 5th 2017

Please remember that
  • the BPL pixels are assumed to sample the same brightest shallow bottom substrate over the whole depth range
    • under the clearest waters in the ROI



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