Specify the Maximum Shallow Water Radiance at null depth

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How to Choose LsM
LsM stand for radiance maximum at the sensor over bright bareland pixels

  • LsM is sampled from bareland pixels in the image which are very bright and expected to be void of vegetation, like sandy beach
  • -LsM/188.7/177.2/164.1
  • Spectral LsM is intended to sit as the intersection of the Brightest Pixels Line and the Soil Line.
    • this choice is not very sensitive
  • LsM is adjusted so as to obtain a satisfactory fit of depths computed for BPL pixels in the calibration diagram: see big star on tarawa-subset_calibration
  • CoefLM : this spectral LsM value may be altered using the CoefLM parameter in the -B argument
    • -B/tclNe/cNorm2.50/Bmin0/cLM1.15
    • a value higher or lower than 1.0 is used to slide spectral LsM up or down the observed Soil Line
    • this does not affect the computed depth, while it widens or narrows the range of computed bottom reflectances (one more priviledge of a ratio method)


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