The purpose is to compare  NOOA's method operated in 4SM RLNmode
 with 4SM method in PANmode
As we have estimated spectral La, it is possible to operate NOAA's method where  Z=bias+slope*ln(LsblueLablue)/ln(LsgreenLagreen)
Slope : in 4SM slope is #1.0, no babbling!  this is because all BOA radiances are normalized to the range 0200
Bias : it is to be estimated against some seatruth  in 4SM, we regress ZRLN against Z3 which is taken to be seatruth,
 and adjust the bias as desired
 depths over very brigher bottoms can only be overestimated in Stumpf's method
 depths over very darker bottoms can only be underestimated in Stumpf's method
 then what if the seatruth dataset does not represent the whole depth range over the whole bottom brightness range in a fair way?
 For RLN modeling
 Z/MSL0.00/RLN_0.96_21.5/n_1/RLBgb1.220/mask_4
 this disables the PANmode and enables the RLNmode
 Enable the RLN mode and run the script
 parameters are: bias Mzero=0.96 and slope Mone=21.5
 they are set manually using a seatruth regression or ProfileAB/R/...
 Lm threshold parameter is enforced: only pixels with Lr[2]>=Lm[2] are modeled.
 tide correction is automatically disabled in RLNmode
 For RLN seatruth regression
 RegressZZv/p/seatruth*depth_points_reproject_pruned/ZM/2_3/0_201/0_30_2.0/*
 and run the script
 See a comparison of the two methods; scatter plot compares computed depths
 I obtained these results in 2003
