Bathymetry and water column correction
LANDSAT 8 OLIP 
at Lee Stocking Island, Bahamas
Image courtesy of the U.S. Geological Survey
7671*7841 30 m pixel size, UTM zone 18


 
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

home


 
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
 
So
I keep digging
until suitable data
become available
 


scene LC80120442014029LGN00, Jan 29th 2014
Work done october 2016


 
Robustness: winter is the time of choice
As I don't have seatruth data, apart from the above speaker_harris_fig_01.png,
I used results obtained on this scene
as a seatruth DTM for the other scenes


Data and Deglinting

TOA TCC: raw image

BOA TCC deglinted image
NO discoloured waters


Calibration is excellent and straightforward in winter
16U data are scaled to allow for comfortable screen display

Calibration diagram for the whole scene
for bands Blue, Green, Red and NIR

 

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

 




Ready for modeling
No Smoothing applied
  
BOA TCC: water column corrected
some areas exhibit an excess of red radiance

 

Retrieved depth
see legend

 




Bottom typing

SAM classified image
see legend for SAM

Average bottom brightness