Bathymetry and water column correction
LANDSAT 8 OLIP 
atat Freeport_South, Bahamas, 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 LC80140432014363LGN00, December 29th 2014
this scene is located just south of 
fpoli-20141229 (same date)
Work done october 2016



Data

TOA TCC: raw image
linear enhancement

TOA TCC: raw image
linear enhancement
Many whitings are seen



Optical calibration
16U data are scaled to allow for comfortable screen display
OPTIMIZED CALIBRATION

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

Calibration diagram for the whole scene
for bands Coastal, PAN, Red and NIR




Ready for modeling
No Smoothing

BOA TCC: water column corrected
whitings look pinkish
and are surrounded by
an excess of red backscatter

Retrieved depth
see legend
Note depths ~10 m at Cay Sal Bank



Bottom typing

SAM classified image
see legend for SAM

Average bottom brightness
note spots of exceptional brightness

 

this scene is located just south of fpoli-20141229 (same date)