Landsat 8 from La Parguera, Puerto Rico
1757*1219, 30 m pixel size, UTM zone 19, october 30th 2015
scene LC80050482013361LGN00, December 27th 2013. Image courtesy of the U.S. Geological Survey

Work done may 2016
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image october 30th 2015
Co-registration
of 2*2 sum-aggregated PAN band       and of LIDAR DTM
is now more securely implemented in 4SM

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under mask 3
Depth Retrievals down to ~30 m
PAN solution is a confirmed substitute to the GREEN solution

PAN solution vs GREEN solution
Blue vs GREEN
under mask_3

KBLUE/KGREEN=0.64
This is OII water type
Maximum depth of bottom detection is ~30 m
  • LsM is for coral sand
    • this calibration assumes that the brightest shallow pixels are located over bright coral sands
  • Land pixels at depth 0 m show where the Soil Line must be placed; this is done by specifying Lw=Lsw-La in both Blue and Green bands
  • Good color separation is observed
  • This means that the conditions for depth retrieval are favorable
  • This plot shows some signs that LswGREEN should be increased a bit
  • Shallowest pixels are ~7.5 m deep
Blue vs PAN
under mask_3

KBLUE/KPAN remains <0.80
 
  • Land pixels are more scattered than in the other plot
    • this might be caused by some mis-registration of the 2*2 sum-aggregated Panchromatic band
  • This plot shows signs that the calibration pf the PAN band still needs somme attention
  • Stronger color separation is observed, particularly in the 0-20 m depth range
  • This means that depth retrieval my be achieved in more favorable conditions
    • but, in these clear OII waters:
      • ZMaxGREEN~=30 m
      • ZMaxPAN      ~=18 m

TCC raw
mask_3 is shown
profile_yellow is shown

this open oceanic waters
Please remember
  • In 4SM, the BPL assumption assumes means that the optical properties of the clearest waters under the current ROI are estimated
  • Should that ROI also harbour less clear water bodies, this shall generally go un-noticed and therefor shall not be accounted for
PAN solution
along profile YELLOW

Modeling by the "PAN solution"
The RED profile shows LIDAR depth
  •   from 20 to 30 km, shelf waters cause depth under-estimation

 
PAN and GREEN solutions yield ......
GREEN solution
along profile YELLOW

Modeling by the "GREEN solution"
The RED profile shows LIDAR depth
  • this plot also shows water column corrected signatures for Coastal, Blue and Green bands
  • topographic lows harbour the brightest bottoms (i.e. coral sands)
....approximately the same depth
GREEN solution  vs PAN solution
along profile YELLOW

PAN and GREEN solutions yield
approximately the same depth retrieval


Minute differences allow for
spectral features to appear
that the GREEN solution cannot resolve
GREEN solution vs PAN solution
along profile YELLOW

This confirms that the PAN solution
is trustworthy to considerable advantage
under mask 3

ZLIDAR-ZPAN
under mask 3
  • Calibration only used pixels inside mask_3
    • BLUE: depth over-estimation
    • RED: depth under-estimation
  • Coastal shelf waters probably cause depth underestimation  over the southern half of this area
 

ZLIDAR-ZPAN in centimeters
 

Z4SM vs ZLIDAR
under mask_3

Z4SM vs ZLIDAR
under mask_3
  • most pixels display along the diagonal: NO NEED FOR FIELD DATA!
  • depth underestimation caused by coastal shelf waters  shows around 13-18 m
    • there is nothing we can do
  • depth overestimation around 20-25 m is caused by slight overestimation of LswGREEN  in the Northern area (blue tones)  : water there might be slightly clearer

ZLIDAR-ZPAN
under mask_3

ZLIDAR-ZPAN
under mask 3
 
mask_3 should be extenced
to cover more of the deep blue areas in this image

TCC WCC
mask_3 is now processed separately here







 



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