#  SIOSEIS scripts to remove the ship heave.
#
#This script was used when the automatic water bottom picker (sioheave_pltwbt_thres) could not correctly identify the water bottom, due to a weak 
#amplitude seafloor interface and/or high levels of noise in the water column. Images and SEG-Y files in the format <filename>_sf (as opposed to #<filename>_topmute_sf) were swell filtered using this script. 
#
#Usage is:
# sio_sf_pickedhorizon <seg-y file> <n>
#
#    seg-y file = seg-y file without extension
#    n = number of traces to be used in the swell filter moving average
#
#          Heave removal using auto water bottom picks via
#          amplitude peak or user defined threshold
#
#      This method of heave removal uses the differences between
#      auto identified sea floor picks and a smoothed seafloor to
#      shift traces.
#
#      The automatic picker in process WBT picks the TWTT of the
#      first arrival and puts it in SEG-Y header word 50.  Process
#      HEADER then copies header word 50 to word 59.
#      Process SWELL then computes the average twtt of the seafloor
#      within a window containing a user defined number of traces.
#      This average is then used shift the central trace within the
#      window, and shifts are written to header word 60. HEADER2
#      overwrites header word 50 with the resulting seafloor time by
#      adding the trace shifts in 60 to the original pick in 59.
#      Process MUTE is then used to mute the water column based on
#      the TWTT of the "heave filtered" seafloor.
#
#      **Remove 'swell' and 'header2' from the procs list in
#        order to simply trace amplitudes within the water
#        column.  See sioheave_pltwbt for additional mods
#        needed to correctly make diagnostic plots of wbt
#        picks**

sioseis << eof
procs diskin header wbt header2 swell header3 diskoa prout end
diskin
    fno 0 lno 999999 ipath ../segy/$1.sgy end
end
header
    fno 1 lno 999999 l6 = l3 l7 = l4 end
end
wbt               
# trace-time pairs of the water bottom from the line to be filtered are entered here. For these data, the water bottom picks were made in Kingdom Suite
# and exported as a text file.
end	    
header2
	fno 1 lno 999999 r59 = r50 end
end
swell
    n $2 hdr 50 index 60 end
end
header3
    fno 1 lno 999999 r50 r59 + r60 end
end
#mute
#    fno 1 ttp 1 0 addwb yes end
#end
#gains
#    type 1 alpha 1.5 end
#end
#agc
#    fno 1 lno 999999
#    winlen 0.05 pctagc 50 end
#end
diskoa
    opath ../segy/$1_sf.sgy end
end
prout fno 1 lno 999999 indices l3 r50 r59 r60 end
end
end