4SM illustrations water_column

This involves the removal of the effect of the shallow water column
on the radiance measured at the RS sensor over shallow water areas.
The result is that the scene is now seen "as if at low tide",
i. e. the water column corrected scene remains
in the same radiometric scaling reference
with non-shallow areas remaining unaltered.

BGR true color composite of TOA radiances radiances are in their natural scaling scheme corrected radiances are shown in processed squares non-shallow pixels remain unaffected	BGR true color composite of BOA radiances radiances are BOA: L=Ls-La all shallow pixels radiances are water column corrected radiances are scaled over the 0-250 range non-shallow pixels are coded at 0 histogram equalization enhancement

	radiances are BOA: L=Ls-La radiances are scaled over the 0-250 range corrected radiances are shown in processed squares non-shallow pixels are just corrected for atmospheric path optically deep waters are coded at 0 LEFT GRN false color composite of BOA radiances

	Spectral Bottom Signature This image show the water column corrected BGR color composite of a CASI flight at Prince Edward Island , Nova Scotia, Canada LEFT insert : Blue versus Red scatter plot of raw data inside red polygon. The exponential decay of shallow water radiances is observed. RIGHT insert : Blue versus Red scatter plot of computed water-column-corrected bottom reflectance, scaled from 0 to 250. The spectral diversity is restored to a great extent through the water column correction process.
	Five targets are shown by color circles The insert shows the water-column-corrected spectral bottom signature of these targets

	The image above shows the water column corrected BGR color composite of CASI flight #4 at Mahone Bay, Nova Scotia, Canada : Spectral Bottom Signature at Mahone Bay (Casi, 16 bands) <<== spectral bottom signature at colored rectangle locations