bahrain-wv2-4

SeaTruth, march 3rd 2011

New seatruth New seatruth under mask 3 New seatruth under mask 3	New seatruth New seatruth under mask 3 The previous seatruth is biased Lsw: deep water radiance in the Yellow band was overestimated: I had to reduce it by 0.7 DN: from 36.0 to 35.3 MaxDepth threshold: imposing a MaxDepth threshold forced even more bias: this feature is disabled in 4SM from now on Biased DTM dataset: it not safe to test the modeling results using a field dataset that (1) lacks a fair representation of the 0-4 m depth range, and (2) has an uneven representation in the 4-6 m depth range: the regression line ZC=offset+slopeZR can go astray using it to set HTide=-offset and CoefZ=1/slope is risky, unless the seatruth dataset ensures a fair representation of over the whole depth range IS THE REGRESSION LINE TO BE TRUSTED?* the practioner must exercise caution ensure that the seatruth dataset is worthy and resort to common sense when inspecting the results when specifying HTide and CoefZ As it turns out, setting HTide=1.5 m and slope=0.96 through visual inspection is just as good: this is shown below
Last seatruth Last seatruth under mask 3 Last seatruth under mask 3	Last seatruth Last seatruth under mask 3 <<== HTide=1.5 m as prescribed <<== coefZ=0.96 for good visual fit <<== and forget about the regression line <<== and forget about wavelengths It only takes a small amount of bias for the offset to be mis-estimated: first we seemed to get 1.0 m and then we seemed to get 1.78 m... The height of tide over LAT is reported to be 1.5 m So it seems reasonable at this stage to assume 1.5 m, and set CoefZ=0.96 so as to place the cloud of points in a suitably diagonal position (a very small correction, hardly needed actually) and forget about the regression line I need to harden the regression process! One way around this problem might be an optimization scheme which would aim at maximizing the R² figure minimizing the RMSE figure. In this respect, the display of both ZR and ZC along a depth sounding profile provides an alternate way to appreciate the offset and slope values that result in an optimized fit of ZC with ZR: I need to implement that feature for the particular case of a DTM
	<<==This plot maps the difference DZ = ZC*0.96 - (ZR+150) in centimeters Brightest areas are within the DZ range -50 to 50 cm, with R²=0.92 and RMSE~=30 cm N=32859 R² has improved markedly from 0.74 to 0.92 RMSE has increased, due to many more points modeled following the decrease of Lsw_yellow
nice -20 4SM.4.03 -Process/producer/02_Mar_2011 -OriginNPA -DB/bahrainM/44_3_7_0/7_48/9318_8807/454.409_2913.873/1_1 -Mis/Bahrain/mosaic/WV02/Multi/TIF/UTM_39_008/0.002_0.002/10_DEC_2010 -LS/0255.0/255.0/255.0/255.0/255.0/255.0/255.0 -WLM/453.0/508.0/581.0/627.0/689.0/744.0/890.0 -WLm/401.0/447.0/511.0/588.0/629.0/704.0/772.0 -cWL/0.500/0.500/0.500/0.500/0.500/0.500/0.500 @cWL/0.800/0.300/0.990/0.990/0.700/0.500/0.500 -CP/0180.9/175.6/157.7/092.6/062.7/030.0/011.9original -Lsw/123.50/96.73/62.93/33.05/24.53/21.82/11.88 -dLsw-00.0/-00.0/0-1.5/002.5/01.00/00.00/00000 -dLsw-00.0/-00.0/0-1.5/001.8/01.00/00.00/00000 -Lw/0006.3/012.1/001.0/000.5/000.0/000.0/000.0_1.1 -LsM/233.9/239.1/253.6/248.5/250.9/299.1/244.5 -SCL/00066/00095/00145/00132/00092/00112/00103 -Lm/0001.0/001.0/001.0/000.5/005.0/255.0/255.0 -M/@000001/@0002/@00003/00004/000005/@0006/00007 -KK2_5_0.3045/Knir4.500/Bm400_BG520_GR585_RN700 -KK2_4_0.3800/Knir4.500/Bm400_BG520_GR585_RN700 /mask_3 @KK2_3_0.8000/Knir4.500/Bm400_BG520_GR585_RN700 -Z/MSL0.00/zplus/cSL1.18/ZMax0.00/cdZ1.00/PAN_1_7/sIG_0w0/N_2/cZ1.000 @Z/MSL1.89/zplus/cSL1.18/ZMax0.00/cdZ1.00/PAN_1_7/sIG_0w0/N_2/cZ1.020 -Z/MSL1.50/zplus/cSL1.18/ZMax0.00/cdZ1.00/PAN_1_7/sIG_0w0/N_2/cZ0.96 -B/tclNe5.00/LBref200_100/Bmin0/cLM1 -deglint/vRbaD/DegTol1.00/F5/L7/GlintM25.0/FN/mDEGLINT1 -extract/v/RawBDH/NIRband7/NIRmax255.0/mBPL2/mSOIL21/FullBDH -calibrate/v/BdSNpZg/BC_5_4_3_1/BDh_12_13_14 -Model/mask_2 @-E4869/8391/1/3249 @-E4869/8391/1000/3249 -Smooth/5/D/Smart+ -RegressZZvp/DTM/0.001_0_0/1.000_0.000/ZM/4_5/0_200/0.0_30_30.0/* -E4869/8391/1/3249	TCC of water column corrected bottom reflectances There is an excellent potential for bottom typing
See BahrainM_ZC-ZR_final.zip on ftp site: It contains BahrainDZ.tif ZC*0.96 - ZR+150 in cm BahrainZC.tif ZComputed in cm BahrainZR.tif your ZRecorded DTM foul.dbf foul.shp outer foul waters foul.shx m2.dbf m2.shp BLUE polygons m2.shx m3.dbf m3.shp RED polygon m3.shx import.dbf import.shp Area imported from your mosaic import.shx	As it turns out, CoefZ=0.96 is peanuts, actually hardly worth mentioning as we lack depth points in the 1-4 m depth range, we can't really conclude other than by saying "Could be that 4SM is really "self-calibrated" when using WV2 data, as it proved to be when using SPOT data, when using IKONOS data, and then when using CASI data" assessing this shall require more reliable WV2 images and seatruth datasets
All this has been a lot of work.	March 3rd 2011 That was my first WV2 image. A hard case at that! I had to chase some loopholes in 4SM It's in the box now.