USAGE:   vpick rpfile start_rpnum [ rpnum_inc end_rpnum]

      VPICK is an interactive velocity picker using SIOSEIS semblance
and a PV-WAVE procedure for contouring and picking.  The picked 
velocity-time pairs are written (appended) to a file name "rpfile".vpick
in SIOSEIS parameter format suitable for inclusion into a SIOSEIS 
parameter file.
      To plot the semblance contours, specify the .mat output from 
SIOSEIS' process velan; the PV-WAVE procedure below uses the Matlab file
format on input.  Use the left mouse button to make the velocity-time
picks, the right mouse button terminates. A white square appears where
picks are made. Picks must be made in order of increasing depth (time).
      A plot of the CMP is placed on the screen next to the PV-WAVE
contour plot.  The left mouse button should be used to pick the
velocities and the right button used to terminate the picks for the
rp.  The seismic plot is displayed using XLOADIMAGE and may be
terminated by typing the letter "q" while the cursor is in the window.
      The picked velocity-time pairs are written to the file "pickfile",
when the script exits, in a format suitable for inclusion in a
sioseis paramter file (as the original vpick did).
      There is no correction facility presently.

      Remember that process NMO holds the last velocity constant to the
end of the trace, so you may want to make a pick at the bottom.

 
      SIOSEIS version 95.10 (27 Oct. 1995) or later should be used since
the vpick script writes Matlab "MAT" files (has a 20 byte file header)
when the velan output filename ends with ".mat".

output file test.vpick contained:
  fno 40 vtp 1471 4.463 1621 5.150 1639 5.363 1675 5.483 1754 5.963
         2218 7.980 2218 7.980 end



      The sample script below can be easily modified for specific
SIOSEIS processing requirements:

#!/bin/csh
setenv DISPLAY rumpole:0.0    # CHANGE THIS FOR YOUR MACHINE!
if( $#argv < 2 ) then
    echo "Usage: vpick filename start_rpnum [ rpnum_inc end_rpnum]"
    exit 1
endif
 
set FILE = $1
set MATFILE = velfile.mat    # these file names are hard-coded else-
set VPICKFILE = picks        # where in this script and in vpick.pro
set START_RPNUM = $2
set STIME = 0.85
set ETIME = 1.15
 
if( $#argv < 3 ) then
    set RPNUM_INC = 1
else
    set RPNUM_INC = $3
endif
 
if( $#argv < 4 ) then
    set END_RPNUM = $START_RPNUM
else
    set END_RPNUM = $4
endif
 
set RPNUM = $START_RPNUM
while ( $RPNUM <= $END_RPNUM )
 
sioseis.sun << eof
procs diskin geom velan END
  diskin
    ipath $FILE fno $RPNUM lno $RPNUM
    si 0.000432 format segy set $STIME $ETIME end
  END
  geom
    gxp 1 74 20 600 end
  end 
  velan
    vels 1480 20 1700 nrp 1 type spec winlen .005
    opath $MATFILE end
  END
END
eof
sioseis.sun << eof
procs diskin plot END
  diskin
    ipath $FILE fno $RPNUM lno $RPNUM
    si 0.000432 format segy set $STIME $ETIME end
  END
  plot
    nibs 75 vscale 30.0 nsecs 0.3 srpath rasplt
    scalar -1 def 0.50 trpin 6
    stime $STIME
    ftag 1 taginc 5 ann fanno fanno $RPNUM
    end
  END
end
eof
xloadimage.sun -geometry 565x850 -r 90 rasplt &
wave runpick
cat picks >> pickfile
@ RPNUM = $RPNUM + $RPNUM_INC
#rm $MATFILE
end
 
; Procedure to read the semblance file output by sioseis
; function velan and pick time-stacking velocity pairs.
; This procedure replaces the matlab processing described
; in the sioseis documentation.
; Currently picks can be made for only one semblance plot
; from one gather at a time. Output from velan should
; contain only one gather.
; Time-velocity pairs will be stored in the file "picks" in
; the format required as input to sioseis nmo.
 
; Author - Mary Rowe, NRL Code 7432 04/30/96
 
; To run the procedure, type:
;     velan, n
; at the WAVE> prompt, where n is the number of contour levels
; wanted for the plot.
 
; set number of contour levels
nlvls = 11
 
; open input and output files
openr, 1, "velfile.mat"
openw, 2, "picks"
 
; read header information and create array of semblance values
params = lonarr(6)
readu,1,params
rpnum = params(0)
nt = params(1)
nv = params(2)
sembarr = fltarr(nt,nv)
 
; read semblance values
readu,1,sembarr
; first 5 values are unknown, start time, time sample interval,
; starting velocity, velocity increment
st = sembarr(1,0)
dt = sembarr(2,0)
sv = sembarr(3,0)
dv = sembarr(4,0)
sembarr(0:4,0) = 0
 
sembarr=rotate(sembarr,6)
x = findgen(nv)*dv+sv
y = findgen(nt)*dt+st
lvls = findgen(nlvls)*((max(sembarr)-min(sembarr))/nlvls)
dcolor = (!d.n_colors-2)/nlvls
clrs = indgen(nlvls)*dcolor
 
; plot contoured semblance values
window, 0, xpos=565, ypos=40, xsize=565, ysize=850
!P.position = [.1,.08,.95,.88]
loadct,5
contour,sembarr,x,y,levels=lvls,c_colors=clrs, $
  xstyle=1, ystyle=1, yrange=[y(nt-1),y(0)], $
  xtitle="velocity (km/s)", ytitle="time (s)"
 
; pick time-velocity pairs
print, "Pick velocities: left button picks, right button to quit"
pair = fltarr(40)
i = 0
!ERR = 0
cursor, v, t, /down
pair(i) = v
pair(i+1) = t
while (!ERR ne 4) do begin
xyouts, v, t, "O", charthick=3, /data
i = i+2
cursor, v, t, /down
pair(i) = v
pair(i+1) = t
endwhile
; store picks in file formatted for sioseis nmo
printf, 2, "fno ",rpnum," vtp ", pair(0:i-1), "    end"
 
close, 2
close, 1
exit
end