Optical calibration, bathymetry, water column correction and bottom typing of shallow marine areas, using passive remote sensing imageries
Bathymetry and water column correction
at Caicos Bank, Bahamas
4018*4149, 30 m pixel size, UTM zone 18, downloaded from USGS
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

Please refer to Bora Bora and Sanaa
for use of the PANchromatic band for water column correction

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
scene LC80090452015011LGN00, Jan 11th  2015.
work done in july 2016


DTM seatruth   RMSE=0.93 m
PAN solution used
I can't explain such a tide correction,
as it excedds by large any tide prediction
at Caicos Bank (0.8 m max)

see legend
Histogram of ZDTM+1.75m   and Z4SM
tide correction 1.75 m

Z4SM va ZDTM+1.75m

What can cause
 such over-estimation
of retrieved depth

  • spectral K values appear to be correct
  • I can only suspect the Soil Line model
  • maybe also the PAN model

Data and Deglinting

TOA TCC: raw image
logaritmic enhancement

TOA TCC deglinted image
same logaritmic enhancement


Optical calibration, optimized
16U data are scaled to allow for comfortable screen display
Calibration diagram
for bands Blue, Green, Red, and NIR
Calibration diagram
for bands Blue, PAN, Red, and NIR

Now ready for Modeling
PAN solution used
TCC BOA water column corrected

Average bottom brightness

SAM mapping

see legend for SAM