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

Panchromatic band
Using the Panchromatic band for water column correction to derive water depth and spectral bottom signature:

Landsat 8 OLIP bandset used for this work

Coastal_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 LC80090452016110LGN00
May 21rst  2016
work done september 2016


This is spring time in the Bahamas


DTM seatruth RMSE=0.64 m
        ZDTM+0.8m - Z4SM
     ZDTM+0.8m - Z4SM
see legend
<==This histogram is a good way 
to estimate a tide height,
rather than the regression

Data and Deglinting

TOA TCC: raw image

BOA TCC deglinted image

16U data are scaled to allow for comfortable screen display

Calibration diagram for the whole scene
for bands Coastal, Green, Red and NIR
KBLUE/KGREEN=0.56 => Jerlov water type OIB+0.58


Calibration diagram for the whole scene
for bands Blue, PAN, Red, NIR


Ready for modeling

BOA TCC: water column corrected

Retrieved depth
see legend


Bottom typing

SAM classified image
see legend for SAM

Average bottom brightness
notice several super_brightness spots