Bathymetry and water column correction
LANDSAT 8 OLIP 
at SanLorenzoChannel, Baja california
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=1, Blue=2, Green=3, PAN=4, Red=5, NIR=6 and SWIR1=7

Work done july 2018
GSD 15 m
 


 
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
 
 
500*2000 HICO image of Bahrain, october 21rst 2013
scene iss.2013294.1021.093734.L1B.Bahrain.v04.14946.20131021200925.100m.hico courtesy of OSU
HICO: Hyperspectral Imager for the Coastal Ocean: GSD 100 m
work done march 2016   

see also WV2 at Bahrain

home

The data

HICO bandset in nanometers for 4SM
WLMin[ 1]=401.2 WL[ 1]=406.9 WLMax[ 1]=412.7   
WLMin[ 2]=412.7 WL[ 2]=418.4 WLMax[ 2]=424.1   
WLMin[ 3]=424.1 WL[ 3]=429.9 WLMax[ 3]=435.6   
WLMin[ 4]=435.6 WL[ 4]=441.3 WLMax[ 4]=447.0   
WLMin[ 5]=447.1 WL[ 5]=452.8 WLMax[ 5]=458.5   
WLMin[ 6]=458.5 WL[ 6]=464.2 WLMax[ 6]=469.9   
WLMin[ 7]=470.0 WL[ 7]=475.7 WLMax[ 7]=481.4    BLUE
WLMin[ 8]=481.4 WL[ 8]=487.1 WLMax[ 8]=492.9   
WLMin[ 9]=492.9 WL[ 9]=498.6 WLMax[ 9]=504.3   
WLMin[10]=504.3 WL[10]=510.0 WLMax[10]=515.8   
WLMin[11]=515.8 WL[11]=521.5 WLMax[11]=527.2   
WLMin[12]=527.2 WL[12]=533.0 WLMax[12]=538.7   
WLMin[13]=538.7 WL[13]=544.4 WLMax[13]=550.1   GREEN
WLMin[14]=550.2 WL[14]=555.9 WLMax[14]=561.6   
WLMin[15]=561.6 WL[15]=567.3 WLMax[15]=573.0   
WLMin[16]=573.1 WL[16]=578.8 WLMax[16]=584.5   
WLMin[17]=584.5 WL[17]=590.2 WLMax[17]=596.0   
WLMin[18]=596.0 WL[18]=601.7 WLMax[18]=607.4   
WLMin[19]=607.4 WL[19]=613.2 WLMax[19]=618.9   
WLMin[20]=618.9 WL[20]=624.6 WLMax[20]=630.3   
WLMin[21]=630.4 WL[21]=636.1 WLMax[21]=641.8   
WLMin[22]=641.8 WL[22]=647.5 WLMax[22]=653.2   RED
WLMin[23]=653.3 WL[23]=659.0 WLMax[23]=664.7   
WLMin[24]=664.7 WL[24]=670.4 WLMax[24]=676.1   
WLMin[25]=676.2 WL[25]=681.9 WLMax[25]=687.6   
WLMin[26]=687.6 WL[26]=693.3 WLMax[26]=699.1   
WLMin[27]=699.1 WL[27]=704.8 WLMax[27]=710.5   PAN
WLMin[28]=836.6 WL[28]=842.3 WLMax[28]=848.0   NIR
Data preparation
 
  • Binning: HICO's original bands 1_to_52 are binned pairwise into 26 new_channels
  • visible bands are placed in channels 1 to 26 of the working database
  • and NIR band is placed into channel_28 of the working database
  • this is the maximum number of channels in the 4SM command line, even using a full HD screen!
  •  
  • Making a PANchromatic: new_channels 10_to_26 are binned into a panchromatic new_channel
  • that's all of the Green-Red region
  • this new_channel is placed in channel_27 of the working database
  • and assigned a wavelength of 705 nm

    •  
    TCC
    TCC deglinted fortunately from looking at the nautical chart we may assume that optically deep waters in excess of 30 m are found at the northern end of the scene
    PANchromatic location of profiles Red and Green are shown
    PANchromatic deglinted

    Deglinting

    Deglinting along ProfileRED
  • adjacency effect does not dominate the NIR signal

    •  

  • by contrast, sea-surface clutter is a significant source of variation of the NIR signal
    • Deglinting channel 26 at 693 nm along a stripe
    Deglinting channel 7 at 475 nm along a stripe