A 740*940 SPOT-1 image of Takapoto atoll,
Tuamotu archipelago, French Polynesia

The 4SM license cost for this image is 39 US$
 



 
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
 

 

 

 

 

 

 

   

 

An excellent image, in spite of marked skyglint which needs to be removed.

Very good and easy calibration

Jerlov water type OIB+0.36: very clear waters

Maximum penetration for XS1 is in excess of 30 m
over bright coral sands bottoms in lagoon waters.

WE LACK A BLUE BAND HERE, for sure!

  x


Sea truth depth sounding lines
are colored in Green:
GPS positioning can be poor!