caicosOLI20151111

Optical calibration, bathymetry, water column correction and bottom typing of shallow marine areas, using passive remote sensing imageries
Bathymetry and water column correction

LANDSAT 8 OLIP
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_1, Blue_2, Green_3, PAN_4, Red_5, NIR_6 and SWIR1_7

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

scene LC80090452015299LGN00
Nov 11th 2015
Work done september 2016
home

DTM seatruth RMSE=0.62 m

Z4SM vs ZDTM+1.7m	ZDTM+1.7m and Z4SM
ZDTM+1.7m-Z4SM	Z_final=Z4SM-1.7m Spectral K is under satisfactory control Tide correction 1.7 m is too much Something is not under control Likely the Soil Line model for the PAN band, i.e. the reference value of the reflectamce of Coral Sands

Data and Deglinting

TOA TCC: raw image
logaritmic enhancement

TOA TCC deglinted image
same logaritmic enhancement

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

Calibration diagram for the whole scene
for bands Blue, Green, Red and NIR
K_BLUE/K_GREEN=0.44 => Jerlov water type OIB+0.1
CoefK=0.8

Calibration diagram for the whole scene
for bands Coastal=1, Blue=2, Green=3 and PAN=4

see that K_COASTAL~=K_BLUE

Now ready for Modeling
No smoothing applied
RED threshold=2.3
PAN solution was used here
A threshold of 2.3 was specified for the RED band,
in order to avoid local artifacts caused by turbidity

BOA TCC water column corrected
No enhancement

Retrieved depth in centimeters
see legend for retrieved depth in cm

Bottom typing

SAM classified image
see legend for SAM

ImageB: average bottom brightness