Caicos Combined Depth
Depth results for a series of co-registered images
are averaged to produce a final DTM

combined depth for 11 bad SLCOFF images
return to main Caicos page


1 - NO NEED for field data, nor for atmospheric correction
2 - this is demonstrated in this website, using a variety of hyper/multi spectral data
Requirements are
1 - homogeneous water body and atmosphere
2 - some coverage of optically deep water
3 - some coverage of dry land
Problems are
1 - the precision on estimated depth is found wanting, because the noise-equivalent change in radiance  of accessible data is too high for shallow water column correction work 
2 - radiance data should be preprocessed by the provider at level 1 in order to improve S/N ratio
3 - exponential decay: the deeper/darker the bottom, the poorer the performances
I keep digging
until suitable data
become available


Since 2003, ETM images have SLCOFF gaps
visible here on the image of Computed Depth
for /ETM_009_045_2010-04-27

It is possible
to merge the results
obtained with a series of SLCOFF images,
in order to generate an acceptable DTM.

In such a time series of images,
the tide difference,
the presence of clouds,
and  the many gaps in the image

are conveniently wiped
out of the final results.

23 images CaicosCZ_UTM19.opf

ALL 23 images


16 images CaicosCZ_UTM19_SLCOFF.opf

16 images SLC OFF

profile tide 23 images

profile tide on 16 images SLCOFF

profile black, 23 images

Standard deviation on 16 images SLCOFF

profile red 23 images

NN on 16 images SLCOFF

profile_green 23 images

profile_green 16 images SLCOFF


at pixel -RL2760/2356
Final Average Depth is 6.76+-0.92m (N=15/23)
at pixel -RL2760/2356
Final Average Depth is 6.71+-0.30m (N=8/16)
at pixel -RL3070/2531
Final Average Depth is 10.80+-3.30m (N=20/23)
at pixel -RL3070/2531
Final Average Depth is 10.93+-2.81m (N=13/16)
at pixel -RL2460/1390
Final Average Depth is 0.84+-0.99m (N=17/23)
at pixel -RL2460/1390
Final Average Depth is 0.89+-0.67m (N=10/16)