 Raw image TCC histeq enhancement |  Zoom : Raw image TCC histeq enhancement |
Deglinted image TCC
Same histeq enhancement as above. - A fairly strong level of baseline skyglint has been removed,
- as well as the swell modulated glint
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Deglinted image, red band_3 - Further histeq enhancement reveals some problems with radiometric quality,
- particularly in the Red band[3]
- which will warrant a fairly high Lm[3] threshold value
Because this image is already geocoded,
there is no simple way to correct
for this very bad feature.
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Before Automatic Deglinting
linear stretch enhancement
"good glint makes for good deglinting prospect!" | 
After Automatic Deglinting
enhancement unchanged
"good glint makes for good deglinting performances!" |
After Automatic Deglinting
Blue band, histeq enhancement
"good glint makes for good deglinting performances!" | 
After Automatic Deglinting
Green band, histeq enhancement
"good glint makes for good deglinting performances!" |
Deglinted image TCC - Deep water areas are not smart-smoothed
- Further histeq enhancement reveals some problems with radiometric quality,
- particularly in the Red band[3]
- which will warrant a fairly high Lm[3] threshold value
- Some scattered clouds resisted deglinting
- Scattered cloud shadows remain anyway
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Zoom : Deglinted image TCC - Deep water areas are not smart-smoothed
- Further histeq enhancement reveals some problems with radiometric quality,
- particularly in the Red band[3]
- which will warrant a fairly high Lm[3] threshold value
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 Deglinted blue band Note the prominent dark bed in the blue band along the outer slope... |  Deglinted green band ....which has no equivalent in the green band: this is a likely candidate for a dense seagrass bed |
image_Z
the likely "dense seagrass bed" along the outer slope
apears to be distinctly shallower |  image_Z b&w |
 image B | 
image LBS - this is a "low-tide", or "water column corrected", RGB true color composite of the shallow bottom reflectance over the scene (linked to a false color composite)
- in this view, each channel is scaled linearly over the range 0-250 for both dryland and shallow areas:
- 0 for the BOA reflectance of a black bod
- 250 for the BOA reflectance of the brightest shallow bottom type that exists over the scene
- the radiometric content of the bottom reflectance signature is not readily "visible" in this view
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image WZ red: areas modeled using bands 1, 2 and 3 green: areas modeled using bands 1 and 2 only
As the NIR band was used for deglinting,
it was not available for modeling of very shallow areas
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image WR The color displays the diameter of the circular smart-smoothing window - from Green (3 pixels for very shallow areas), Blue (5), Yellow (7) , Orange (9),
- through to Pink (11 pixels for deepest areas)
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Optical calibration
Because of the heavy glint, and quite distinctly here because clean bright sandy detritic bottoms would appear to be scarce in this environment (biofilms, seagrass, algae and oolit formation all involve photosynthetic acitvity at the sea bottom surface), the calibration of optical properties is requires some experience. |
Optical calibration
Add to it that we do not have any seatruthed experience of the proper way to set operational wavelengths for the 4 wavebands: this means that a significant CoefZ factor might be needed in order to adjust computed depths to seatruth reality.
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Optical calibration
Based on in-situ data, Louchard et al. state that "the IOPs were assumed to be uniform over the study site". - But we found clear signs of significant variations of the operational attenuation coefficients at various locations in the image:
- In particular, less clear waters are associated with the crest of the oolitic sand wave.
- This does not help to secure the Brightesst Pixels Line.
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