4SM tutorial
on a 500*500 Landsat TM
4 bands image (1985)
of Negril Shores, Jamaica,

UTM georeferenced with sea-truth dataset

Courtesy of Tomy Lindell, University of Upsala, Sweden.    

Also refer to work done in 1998: Erim Marine 98

work in progress

 
 
 
   
back to 4SM tutorial        next to Prepare your image           
 
 
    Quite a difficult image
  • too small, not enough shallow pixels
  • 30 m pixels are very large; only 70 pixels from beach to deep waters
  • fairly dark TM2 band: low dynamic range
  • striping
  • faithful bright sandy pixels fairly scarce
  • 0-5 m depth range poorly represented
  • possibly turbid waters along the beach
  • heterogeneous open waters
  • no swell-modulated glint
  • non-DGPS sea-truth data


 

TCC

FCC
   
   
 
 

First let's take a look at the results I finally obtaned
through an intnsive use of seatruth field data

 

 



Sea truth correlation: r 2=0.73 RMS=1.40 m
This improves markedly on results obtained in 1998.

neg85 mapZ   is the depth contour map obtained in 1998.

 
   

Three depth profile

Red: computed depth
Black: Sea-truth depth
Then we shall try to see, step by step, whether it is possible,
 to reach there without using that field dataset.

Several key points have to be addressed:

        • Which pair of bands for measuring the ratio KiKj?
        • What wavelengths?
        • What Lsw values?
        • What La values?
        • Is the water body homogeneous? 
        • What smoothing scheme?
        • What about the electronic noise?
        • SIG or not SIG?
 
 
Flow chart
Bottom typing was the ultimate goal of this venture.
Whether it can be of any help for coastal management remains to be seen.
 
 
 
 
toto


 
   
   
   
 









 

   




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