4SM on OLI at Caicos Bank, Bahamas

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

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_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 LC80090452015235LGN00 Aug 25th 2015.
Work done july 2016
home

DTM seatruth RMSE=0.65 m

Z4SM vs ZDTM+0.7m	ZDTM+0.7m and Z4SM
ZDTM+1.0m-Z4SM see legend	Z_final=Z4SM-1.0m Spectral K is under satisfactory control Tide correction 1.0 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, optimized
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=0.60 => Jerlov water type OIB+0.79	Calibration diagram for the whole scene for bands Coastal, Green, PAN, and Red
Reflectance (0-1) of the path radiance Ra for this scene 0.108 0.080 0.050 0.043 0.028 0.013 0.002	Reflectance (0-1) of the water volume Rw for this scene 0.017 0.017 0.001 0.001 0.0 0.0 0.0

Now ready for Modeling
No smoothing applied
PAN solution applied

BOA TCC water column corrected
Linear enhancement

Reddish areas denote some "pollution"
in the RED band,

possibly some "whiting" being flushed out of the platform
more likely, incomplete "deglinting" of the path radiance

Retrieved depth in centimeters in decimeters

see legend for retrieved depth in cm

Bottom typing

SAM classified image
see legend for SAM

ImageB: average bottom brightness