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

Calibration of full TM/ETM imageries

and the winner is

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
I keep digging
until suitable data
become available

Caicos Bank: 18 ETM scenes

Caicos Bank: 18 ETM scenes

ETM_009_045_1999-09-20 Caicos

  September: K1/K2=0.58 WL[2]=567 nm ==> OIB+0.94
seatruth   Z   LB

ETM_009_045_2001-01-28 caicos

January: K1/K2=0.47 WL[2]=568 nm OIB+0.42
seatruth   Z   LB

ETM_009_045_2001-07-07 Caicos

turbid atmosphere, very bright image, lots of clouds
July: K1/K2=0.62 WL[2]=574 nm   ==>   OII+0.24

seatruth     Z     LB


February: K1/K2=0.50 WL[2]=566.6 nm ==> OIB+0.53
seatruth    Z     LB


lots of clouds
July: K1/K2=0.46 WL[2]=567 nm   ==>   OIB+0.36

seatruth     Z     LB


lots of clouds
January: K1/K2=0.446 WL[2]=562 nm   ==>   OIB+0.18

seatruth     Z     LB


very nice
January: K1/K2=0.446 WL[2]=562 nm   ==>   OIB+0.18

seatruth     Z     LB


very nice
February: K1/K2=0.540 WL[2]=569 nm   ==>   OIB+0.80

seatruth     Z     LB


very high glint, questionable
May: K1/K2=0.580 WL[2]=567 nm   ==>   OIB+0.95

seatruth     Z     LB


very nice
December: K1/K2=0.550 WL[2]=567.4 nm   ==>   OIB+0.80

seatruth     Z     LB


very nice
December: K1/K2=0.510 WL[2]=571.4 nm   ==>   OIB+0.71

seatruth     Z     LB


difficult, blue sky
February: K1/K2=0.470 WL[2]=573.3 nm   ==>   OIB+0.63

seatruth     Z     LB


difficult, blue sky
April: K1/K2=0.470 WL[2]=571.4 nm   ==>   OIB+0.63

seatruth     Z     LB


very nice, blue sky
April: K1/K2=0.470 WL[2]=562.9 nm   ==>   OIB+0.32

seatruth     Z     LB


very cloudy, quite good seatruth
December: K1/K2=0.470 WL[2]=569.0 nm   ==>   OIB+0.45

seatruth     Z     LB


clear image, quite good seatruth
January: K1/K2=0.480 WL[2]=564.9 nm   ==>   OIB+0.40

seatruth     Z     LB


cloudy image, quite good seatruth
January: K1/K2=0.515 WL[2]=569.8 nm   ==>   OIB+0.69

seatruth     Z     LB


clear TM image
November: K1/K2=0.50 WL[2]=576.3 nm   ==>   OIB+0.81

seatruth     Z     LB


Miscellaneous Landsat images

Miscellaneous Landsat images

Alacranes atoll ETM

  Z     BSC
Chinchorro atoll ETM

 Z     BSC
DaviesReef atoll ETM

  Z     BSC
Heron island ETM


Great Abaco, Bahamas

quite     nice


And the winner is TM_012_044_1986-02-17

This is Long Island in the Bahamas   TM_012_044_1986-02-17: I seem to have lost the image

  • This provides the most desired proof that 4SM's assumptions are trustworthy.
    • WLgreen is set to 577.3 nm here : cWLgreen~=0.6
    • WLblue and WLred at mid-wavelength are satisfactory
    • Knir at 4.5 m-1 is quite satisfactory, as usual
  • ==>>>>Where it is seen not to be the case, there must be a good reason.
    • maybe WLgreen is not set to an appropriate value
    • and/or the illumination conditions aren't ideal
    • and/or the water body is not as homogeneous as expected
    • and/or the brightest bottom type is not present over the whole depth range
  • That was in 2009:
    Thanks to hyperspectral evidence in 2015,

    I now think otherwise