Bathymetry and water column correction
at SanLorenzoChannel, Baja california
Image courtesy of the U.S. Geological Survey
7671*7841 30 m pixel size, UTM zone 12
Using the Panchromatic band for water column correction
to derive water depth and spectral bottom signature:

Landsat 8 OLIP bandset used for this work
Purple=1Blue=2Green=3PAN=4Red=5NIR=6 and SWIR1=7


scene LC80340432016285LGN00, October 11th 2016
DATE_ACQUIRED = 2016-10-11
    SCENE_CENTER_TIME = "17:48:10.3135120Z"

Work done november 2016

GSD 15 m Rsudio_sharpened
data are scaled into a weird range

No sweat though: 4SM is a "ratio" method

Ground truth
How sad!

October 11th 2016    vs   Sonar Depths
RMSE=1.64 m


Sonar Two Days seatruth depths raster
not corrected for tide

15 m GSD
see depth legend

October 11th 20146   vs   DTM

DTM resampled to 15 m GSD

DTM - October 11th 20146
see legend 

Data and Deglinting

TOA TCC: raw image
logarithmic enhancement

BOA TCC deglinted image
logarithmic enhancement
Glint regressions using SWIR1

R2 values are fairly high
15 m pansharpening does not increase noise
R_sharpened data include a very large offset

R-pansharpening slight mis-registration
can cause artifacts

Optical calibration
for the whole image

16U data are scaled to allow for comfortable screen display

Calibration diagram
for the whole image
for bands Blue, Green, Red and NIR


Calibration diagram
for the whole image
for bands Blue, PAN, Red, NIR
  • 0-30m: KBLUE/KGREEN=0.466
    • Jerlov water type OIB+0.1
    • very clear waters
Calibration diagrams are just as good
for a 15m GSD pansharpened image
as it is for original 30 m GSD data


Ready for modeling

BOA CC WCC normalized
CoefNorm=7.5 (usually 2.5): shows much more
BGR color composite:
  • Blue  =Coastal band
  • Green=Green   band
  • Red    =Blue     band

Retrieved depth
see legend

Profile Black

Profile Black

Location of Profile Black
  • WEST sections A and B: bad and puzzling results
    • probably swirling turbid waters play trick
  • EAST sections C and D: very nice results

Bottom typing

SAM classified image
see legend for image SAM

Average bottom brightness
see legend for image B
How weird that the scaling of the data
by the R pan-sharpening routine
does not preclude SAM mapping!

Well: that's what they mean by
a "ratio" method!

Download 57 MB
from my GoogleDrive

Contains the following
Channel Descriptor    file="slcOLI_20161011_15mresults.pix";
 1 U8 SAM bottom typing-----------------------------
 2 U8 image B average bottom brightness (0-200)-----
 3 U8 image Z in decimeters-------------------------
 4 U8 WCC reflectance (0-250) at 440.0 nm-----------
 5 U8 WCC reflectance (0-250) at 480.0 nm-----------
 6 U8 WCC reflectance (0-250) at 560.0 nm-----------
 7 U8 WCC reflectance (0-250) at 590.0 nm-----------
 8 U8 WCC reflectance (0-250) at 655.0 nm-----------
 9 U8 WCCnormalized (0-250) at 440.0 nm>B-----------
10 U8 WCCnormalized (0-250) at 560.0 nm>G-----------
11 U8 WCCnormalized (0-250) at 480.0 nm>R-----------
12 S16 Z4SM in centimeters--------------------------
13 S16 ZDTM in centimeters--------------------------
14 S16 ZDTM-Z4SM in centimeters---------------------


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