QuickBird and GE at Shiraho Reef, Japan

Quickbird at Shiraho Reef, Japan
image acquired July 2nd 2007, courtesy of Antoine COLLIN (23 december 2014)

Please refer to "Mapping VHR Water Depth, Seabed and Land Cover Using Google Earth Data"
Antoine Collin, Kazuo Nadaoka and Takashi Nakamura. ISPRS Int. J. Geo-Inf. 2014, 3, 1157-1179; doi:10.3390/ijgi3041157

4SM work done over 5 days early march 2015, then in april 2015
Because this study had to be restricted to the 0-5 m depth range, the estimation of ratio K_blue/K_green is a bit uncertain

Challenges

how does QUICKBIRD compare with other multispectral images?
- the PAN band has a wide response curve
- this appears to preclude an acceptable optical calibration
can we use a PAN-sharpenned QUICKBIRD image for shallow water work?
- the answer is : YES
can we use a GoogleEarth derived QUICKBIRD pansharpenned image for shallow water work?
- the answer is : YES, with minor restrictions (lousy warping, 8-bits coded, weird)
- but deglinting is impossible as there is no NIR band: this is a very serious drawback

home

Three 8-bits datasets
courtesy of Antoine Collin (23 december 2014)

	size	footprint	X0	Y0
The Quickbird image from DG QB_MUL_ortho_resized.tif 2.4x-2.4 m QB_PAN_ortho_resized.tif 0.6x-0.6 m	1969x4590 7873x18358	2.4x-2.4 m 0.6x-0.6 m	UTM 52N 15650.4	UTM 52N 2710591.2
The PAN-sharpenned Quickbird 4-bands image QB_Pansharpened_BGRIR.tif 0.5x-0.6 m land_mask.tif water_mask.tif cloud-shadow_mask.tif	8924x18001	0.5x-0.6 m	UTM 51N 624518.7	UTM 51N 2702792.6
The image mosaicked from 39 VHR GoogleEarth views at a GE eye altitude of 1100 m GE_RGB, no NIR band.tif	idem	idem	idem	idem

First process DG's 2.4 m QuickBird image
MULTI and PAN

Review the QUICKBIRD response curves

Quickbird data was resampled from 11 bits to 8-bits by Collin et al.
QB_PAN_ortho_resized.tif: I reduced the image from 0.6 m GSD to 2.4 m GSD through sum-aggretation
- this exported a 1968 x 4589 QB_PAN_ortho_resized.pix image in PCIDSK format
QB_MUL_ortho_resized.tif:
- this image is 1969 x 4590
- I exported from row 1 to row 1968, and from line 1 to line 4589 to QB_MUL_ortho_resized.pix
Those two now overlay nicely

I imported into my shirahoQB.pix working database structure

Blue is in band 1
Green is in band 2
PAN is in band 3
Red is in band 4
NIR is in band 5

I created a mask

to map in green cloud areas, the reef front, and all of the open sea waters
to map in blue the fringing reef, the reef moat and the reef crest
- optical calibration shall only account for the blue areas

Deglinting

TCC

TCC deglinted

Deglinting along profile_white

Glint regressions are excellent

Note that regressions involving the PAN band
are slightly fuzzy

Profile White (left)

profile A: there is no water surface clutter in the lagoon: the lagoon does not need deglinting
profile B: glint is very strong over open waters
- between waypoints B1 and B2, the profile samples cloud shadows

Deglinting not needed

Deglinting is not needed for the lagoon
This is fortunate, as deglinting dammages very shallow pixels, which are abundant in this scene

Optical calibration
calibration dataset is not deglinted

Calibration diagram
for bands Blue, Green, Red and NIR
Calibration data are not deglinted
They only sample the lagoon (Blue areas)

Jerlov's water type is ~OII
The calibration dataset includes emerged fringing reef and the reef crest, which are forced to null depth

I failed to achieve an acceptable calibration of the PAN band, possibly because of the unusual response curve of QUICKBIRD's PAN band

Profile Red
no deglinting
see location of Profile Red

Profile RED by the "Red solution"
Red against Blue and Green
Also shows the water column corrected radiances

Profile RED

This compares the Green and Red solutions

Water column correction
no deglinting

TCC
enhancements are identical

TCC water column corrected, TOA
enhancements are identical