• stepDTM.............
• FullDTM.............

• Textfile FileName.txt contain up to 50 LineName, each with up to 1000 records
  • Format for LineName: > LineName -
  • Format for depth point: XUTM YUTM ZED WZ
  • #Disable any line with a "#" character
• GPS or DGPS: just to make a note of positioning details of sea truth data

• This is optional and useless: better use a spreadsheet to prepare the textfile
• coefXY_deltaX_deltaY/coefZR_deltaZR
  • sea truth data require to be offset and scaled
• these parameters provide offset and scaling factor as required
  • X and Y are to be converted to UTM coordinates in kilometers and offsets are applie
  • ZR are to be converted to meters and tide-corrected as required
  • X =deltaX + X * coefXY
  • Y =deltaY + Y * coefXY
  • ZR =deltaZR +ZR *coefZR

• Textfile format: data for regression
  • ZM: text file format is X Y ZR
    • Read ZR from textfile
    • Model ZC from scratch at each depth point (recommended)
  • ZR: text file format is X Y ZR ==> Read ZR from textfile and Read ZC from image
  • ZT: text file format is X Y ZR ZC ==> Read both ZR and ZC from textfile

• Limited range for regression
• WZm_WZM............regression only for sea truth pixels with WZmin<=WZ<=WZmax
• BZm, BZM..............regression only for sea truth pixels with BZmin<=B <=BZmax
• ZRm_ZRM..............regression only for sea truth pixels with ZRmin<=ZR<=ZRmax

• Groups: Sea Truth Text File may describe up to 40 groups of depth points, like one/several group(s) of scattered depth points, or a series of depth sounding lines
  • Each group may contain up to 1000 depth points
• Group name: In the text file, each group is introduced by a header
  • > LineName1 -
  • > LineName2 -
  • > LineName3 -
  • ...
• Records: followed by up to 1000 records with format XUTM YUTM ZR (or XUTM YUTM ZR ZC
• NameLine parameter may be specified as LineName (a line name or a line number)
  • ALL: if NameLine is specified by "ALL" in the -RegressZZ... argument, then all depth points from whatever LineName(s) shall be used for computing the regression
  • *: if NameLine is specified by "*", then all depth points from whatever LineName(s) shall be used for computing the regression
  • LineName: else, only depth points that belong to specified LineName shall be used for computing the regression

optional
 

• Plot_16 append Plot_N to burn the seatruth pixels in Channel-Seatruth

• First offset and scale the recorded data (use a spreadsheet)
• Assign each recorded point to relevant pixel through georeferencing information provided
• Then
  • ZR: either read ZC values from 16S channel imageZG of image.pix file
  • ZM: or preferably model each relevant pixel in actual and updated conditions
• Then compute the linear regression of ZC=A + B * ZR
• Text file output: then write a database_regressZZ.txt text file
• PostScript output: then format and execute a GMT script database_regressZZ.sh to display the data and the regression in a database_regressZZ.eps PostScript file

• compute
  • average xm of X values (ZRecorded)
  • average ym of Y values (ZComputed)
  • A=Sum[(x-xm)*(y-ym)]
  • B=Sum[(x-xm)*(x-xm)]
  • C=Sum[(y-ym)*(y-ym)]
  • a =A/B
  • a'=A/C
• regression line y=a * x + b
  • regression slope a
  • regression bias b=ym - a * xm
• determination coefficient R2=a * a'
  • R2=0.059 means very poor correlation
  • 0<=R2<=1 ==> -1<R<+1
  • The sign for R must be chosen manually
• correlation coefficient r=sqrt(R2)

• The root-mean-square error is a measure of the variability of measurements about their true values.
• The rms error is estimated by taking a sample of measurements, and comparing them to their true values.
• These differences are then squared and summed.
• The sum is then divided by the number of measurements to achieve a mean square deviation.
• The square root of the mean square deviation is then taken to produce a characteristic error measure in the same units as the original measurements.
• The rms error is directly comparable to the concept of a standard deviation.