Bathymetry and water column correction
at SanLorenzoChannel, Baja california
Image courtesy of the U.S. Geological Survey
Using the Panchromatic band for water column correction
to derive water depth and spectral bottom signature:

Landsat 8 OLIP bandset used for this work
Purple=1Blue=2Green=3PAN=4Red=5NIR=6 and SWIR1=7

Work done july 2018
GSD 15 m

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
I keep digging
until suitable data
become available

Dans la catégorie "general" :

4SM and attenuation coefficient 2K

What about the operational attenuation 2K in the simplified RTE? This all important question is discussed in detail by Maritorena et al, 1994, in their paper "Diffuse reflectance of oceanic shallow waters: influence of water depth and bottom albedo". I have come to suspect that shallow areas in a deglinted remote sensing image allow the practioner to derive a very good estimation of the value of spectral operational 2K in units of m-1 : Radiances in units of native image DNs may used: conversion into reflectances (0-1) is not a requirement when operating a "ratio m...

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Assessment of current situation, and validation of 4SM

1 - ASSESSMENT of 4SM============= "What is your assessment of the current state of the art and your algorithms in particular?" (sept 9th 2011) For me, the "current state of the art" is After over 30 years of generous funding, the basics for a simplified radiative transfer equation have been very well documented (by Philpot then Maritorena), along with the risks one has to take/assume prior to "operating" this model. no one should indulge in ignoring the water volume reflectance, lest they'll have to pay the price in the form of badly unde...

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Presentation of 4SM for the busy executive

Shallow water depth and bottom type from satellite image   Further to Lyzenga's and Stumpf's methods, most existing empirical methods still need the following and only deliver shallow water depths atmospheric correction conversion into units of reflectance an existing depth sounding dataset that covers faithfully the whole ranges of bottom brightnesses and shallow depths segmentation of shallow areas into several bottom brightness classes, irrespective of depth specify a, b and c for each class: Z= aX...

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