shiraho-3

home

0.5x0.6 m GoogleEarth-derived QB mosaic
no NIR band: WHY IS THAT?
would appear to have been pansharpenned using FuzeGo software
http://www.scenesharp.com/pulse/industry-news/96-nb-ottawa-invests-in-scenesharp-technologies-inc

How can it be 0.6 m footprint?
The answer is:
by "positioning the virtual Google Earth eye at the proper altitude and geometry"
against a backdrop of a 0.6 m panchromatic image

0.5x0.6 m footprint

No NIR band
NIR-based deglinting is impossible.
Lucky there is no adverse wind-generated sea surface clutter over the reef system.
This is a severe limitation of GE-derived images for shallow water work.

Dynamic range
This data fills the whole 0-255 dynamic range: this helps a lot

Mask

I used strictly the same mask into channel_4 already used in shirahoQBPS_20070702.pix

Optical calibration

Calibration diagram

The calibration data only samples the reef moat and crest: that's the 0-5 m depth range in BLUE, as the GREEN areas are excluded.
- deeper than that, over the outer reef slope, deglinting would be absolutely necessary, but is impossible.

Noise/Dynamic range

GE image is much easier to calibrate, thanks to the wider dynamic range and lesser level of noise

Lsw and Lw

The main features of a satisfactory calibration are available

it requires a seasonned practioner though
the estimation of deep water reflectance Lsw and water volume reflectance Lw is more a question of experience and logic with this image...

WEIRD

GE-derived image exhibits a very weird bi-dimensional histogram
Blue vs Red raw radiances here.
This has nothing to do with Mother Nature!!
Do you have a clue?
Is it caused by 0-255 scaling at GoogleEarth? Or their pan-sharpenning process?

Water column correction

GE TCC TOA
raw data
Please note : linear enhancement

shirahoGE_20070702_TCC_water_column_corrected

GE TCC TOA
water column corrected data
Please note : enhancement is identical
to that of the raw TCC

GE retrieved depth