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
scene LC80090452014312LGN00, Nov 8th  2014
This is autumn time in the Bahamas
Work done july 2016


DTM SeaTruth RMSE=0.59 m
tide correction applied: 1.7m
RMSE=0.59 m


tide correction applied: 1.7m

see legend

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 under mask_3
for bands Blue, Green, Red and NIR
KBLUE/KGREEN=0.55 => Jerlov water type OIB+0.54

This calibration is fairly secure,
but results shall show that
bottoms are green and dark everywhere.

Calibration diagram under mask_3
for bands Coastal, Blue, Green, and PAN

[X1 & 2] vs [X3]
This plot justifies that
KCOASTAL   must be significantly reduced
from  K1=0.115 m-1  to   K1=0.096 m-1  
This is done through the -CP... argument

Reflectance (0-1)
of the path radiance Ra for this scene
0.106 0.079 0.045 0.038 0.024 0.009 0.001 

Reflectance (0-1)
of the water volume Rw for this scene
0.022 0.019 0.003 0.002 0.0 0.0 0.0


Now ready for Modeling
No smoothing applied
PAN solution applied
BOA TCC water column corrected
scaled 0-250
Linear enhancement

Quite remarkable:
bottoms everywhere exhibit
a fairly GREEN and dark signature

BOA TCC deglinted
scaled 0-250
Same scaling and linear enhancement


Bottom typing
SAM classified image
This is November 2014

see legend for SAM
ImageB: average bottom brightness
This is November 2014


Créer un site
Créer un site