lsiOLI20160204

scene LC80120442016035LGN00, February 4th 2016
Work done september 2016
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Robustness
As I don't have seatruth data, apart from the above speaker_harris_fig_01.png,
I used results obtained on lsiOLI_20140129 as a seatruth DTM
The result is astounding,
knowing that part of the fuzziness is caused by slight misregistration of the PAN band.
No smoothing applied

Regression
February 4th 2016 vs Jan 29th 2014
This is a test of the robustness of 4SM

ZR-0.50m - ZC
February 4th 2016 - Jan 29th 2014

Discrepancies
Three specific sources of discrepancies must be considered

Cloud shadows: they cause over-estimation of retrieved depths. I could not find a way to avoid it.
Misregistration: the 30 m re-sampled PAN band is misregistrated by one pixel in both row and line. This causes fuzziness, and overestimated depths on occasion.
Variation of water optical properties: they cause local over -or under- estimation of retrieved depth

Robustness
The results are much more robust than I expected!
I intend to produce
a Combined Depth raster
out of all these results.

Data and Deglinting

TOA TCC: raw image logaritmmic enhancement	BOA TCC deglinted image logaritmmic enhancement
	Winter is the time of choice Clear atmosphere, hardly any glint Homogeneous waters, particularly Blue bands (most unusual), from Exuma Sound to Tongue Of The Ocean and to open ocean No local patch of discoloured waters, although the PAN band comes to near extinction between waypoints B2 and B3, where depth is 5-7 m

Top notch optical calibration
16U data are scaled to allow for comfortable screen display

RAW CALIBRATION Calibration diagram for the whole scene for bands Blue, Green, Red and NIR	OPTIMIZED CALIBRATION Calibration diagram for the whole scene for bands Blue, Green, Red and NIR
Raw calibration The optical calibration in 4SM assumes that BPL pixels represent spectrally neutral bottom reflectances Not quite true for bottom type_10, which is brightest ooid sands LsM reflectances for best fit -LsM/337.4/350.8/310.6/328.8/326.2/292.9/680.2 -CP/0228.5/221.5/129.1/000.0/024.0/000.0/000.0	Optimized calibration Optimization of the optical calibration enforce spectrally neutral bottom reflectances for bottom type_10, which is brightest ooid sands See that optimization achieves it This involves fine-tuning of LsM reflectances -LsM/322.3/330.1/297.1/347.0/305.5/292.9/680.2 -CP/0227.3/218.4/133.7/000.0/026.5/000.0/000.0
NIR CALIBRATION Optical calibration of the NIR band is excellent 2K_NIR~=6 m^-1 seems to fit OLI data	La CALIBRATION Blue vs Red When the atmosphere is thin, the Vegetation Line assumption allows for straightforward estimation of La = Lsw - Lw in the Blue range

Ready for modeling
No Smoothing

BOA TCC: water column corrected

Retrieved depth
see legend

Bottom typing

SAM classified image
see legend for SAM

Average bottom brightness