Landsat 8 from DryTortugas to Key West, Florida Keys
6000*2000, 30 m pixel size, UTM zone 17
scene LC80160432013102LGN01, April 12th 2013. Image courtesy of the U.S. Geological Survey
with USGS's EAARL LIDAR seatruth dataset merge_5.tif
With a DTM at hand,
I can decide
which operational practices in 4SM should be ruled out
and which are confirmed

Work done jan/feb 2014 for Dry Tortugas National Park area
 
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

This is spring in Florida
see Hyperion and ALI at Florida Keys
 


 
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
 
home

The "PAN solution"
only uses Purple, Blue and Green against the PAN band.

The PAN solution uses all the information contained in these four wavebands.
as illustrated in the image below,
where grey pixels have been processed by the "PAN solution" with very low threshold Lmpan=0.5,
and red pixels by the "RED solution" with high threshold Lmred=5.0.









Water column correction: retrieved depth
Performance of the PAN band reaches ~30 m over very bright bottoms in this OIB+0.1 water type of Jerlov
Profile Blue over Dry Tortugas National Park

TCC deglinted/smoothed
with location of Profile Blue

TCC raw

Retrieved depth by the GREEN solution
with location of Profile Blue

Retrieved depth by the PAN solution
with location of Profile Blue

the GREEN solution on Profile Blue
bands 1 and 2 versus GREEN
the DTM profiles are shown in red

the PAN solution on Profile Blue
bands 1, 2 and 3 versus PAN
the DTM profiles are shown in red
The GREEN solution yields
poorly contrasted
water column corrected bottom signatures:
bottom typing shall be mainly be based on brightness
The PAN solution reveals
more contrasted
water column corrected bottom signatures:
this enhances the potential for bottom typing
   





Water column correction: shallow bottom reflectance

image B
average bottom brightness
The PAN solution
 NDR=(LB1-LB3)/(LB1+LB3)
Normalized Difference Ratio
  • negative values are mapped in shades of green
  • positive values are mapped in shades of purple
  • LB are BOA water column corrected reflectances

TCC water column corrected
by the PAN solution
BOA, enhanced





Command Line
january 30th 2014
for the Dry Tortugas National Park area
nice -20  4SM   -Process  -Origin/USGS                   
-DB/drytortugas_20130412/40_3S_7S_0s/7_44/6000_2000/279.215_2754.585/1_1   
-Mis/Florida/DryTortugas/Landsat/OLIP/TIF/UTM_++1_008/0.030_0.030/12_APR_2013   
-LS/030000.0/30000.0/30000.0/30000.0/30000.0/30000.0/30000.0           
@WLM/450.0/510.0/590.0/680.0/670.0/880.0/1650.0       
@WLm/430.0/450.0/530.0/500.0/640.0/850.0/1570.0       
-WL/0440.0/480.0/535.0/590.0/615.0/865.0/1610.0       
-import/data*LC80160432013102LGN01               
-LsM/263.0/264.3/229.1/231.9/233.3/228.0/430.2           
-Lsw/133.5/095.2/043.1/037.2/023.1/009.6/018.2           
-dLsw003.0/003.0/002.0/001.0/000.9/000.0/000.0           
-Lw/0035.0/025.2/005.0/000.0/000.0/000.0/000.0           
-SCL/01083/01168/01383/01423/01557/02015/00896           
-M/@000001/@0002/00003/00004/@0005/@0006/00007           
-Lm/0001.0/001.0/001.0/000.5/005.0/255.0/255.0           
-KK2_3_0.600/Knir16.5/Bm400_BG500_GR600_RN700/mask_3       
-Z/0.00d/cSL1.50/N_4/NDR_43_1000_zDTM/mask_3           
-B/BclNe/cNorm5.00/cLM1 .1 0.85 .5               
-deglint/vRbaD/q/F1/L6/FN/mDEGLINT1/GlintM60.0           
-extract/v/rawBDH/FullBDH/NIRband6/NIRmax5.0/mapBPL/mBPL4   
-calibrate/va/BDSNpzg/plot_BPL/BC_6_5_3_2/BDh_12_13_14       
-Model/v/runWV2/makeClouds/mask_3    -LL10           
-Smooth/5/D/Smart+    -Tpsv/2/4/Text/Bmin170/PanCode1 0.80    
-ProfileAB/ZrvWB/profile_blue/DTM/chAB_1_2_3_5 /0_201/0_50_50