REFERENCES

Biondi, B., and Palacharla, G., 1996, $\mbox{3-D}$ prestack migration of common-azimuth data: Geophysics, 61, no. 6, 1822-1832.

Claerbout, J. F., 1985, Imaging the Earth's Interior: Blackwell Scientific Publications.

Huang, L., Fehler, M. C., and Wu, R. S., 1999, Extended local Born Fourier migration method: Geophysics, 64, no. 5, 1524-1534.

Le Rousseau, J., and de Hoop, M., 1998, Modeling and imaging with the generalized screen algorithm: 68th Ann. Internat. Meeting, Soc. Expl. Geophys., 1937-1940.

Mosher, C., and Foster, D., 2000, Common angle imaging conditions for prestack depth migration: 70th Annual Internat. Mtg., Society of Exploration Geophysicists, Expanded Abstracts, 830-833.

Ristow, D., and Ruhl, T., 1994, Fourier finite-difference migration: Geophysics, 59, no. 12, 1882-1893.

Sava, P., 2000, A tutorial on mixed-domain wave-equation migration and migration velocity analysis: SEP-105, 139-156.

SEG Workshop, 2001, Seismic imaging beyond Kirchhoff: Society of Exploration Geophysicists.

Stoffa, P. L., Fokkema, J. T., de Luna Freire, R. M., and Kessinger, W. P., 1990, Split-step Fourier migration: Geophysics, 55, no. 4, 410-421.

A  Main program

# mini WEI example code
# Performs modeling and migration by downward continuation
# using Split-Step Fourier with N reference velocities
# Authors: Paul Sava (paul@sep) and Bob Clapp (bob@sep)
program WEImini{
  use sep+wei_util+wei_process+wei_mig+wei_cig+wei_kxmig+wei_slo+wei_ssf+wei_wem 
  implicit none
  logical :: verb
  integer :: stat,ierr,iverb,n,i
#ifdef SEP_MPI
  call MPI_INIT(stat)
  call  set_no_putch()
#endif
  call sep_init(SOURCE)
#ifdef SEP_MPI
  call MPI_COMM_SIZE(MPI_COMM_WORLD, n,ierr)
  call MPI_COMM_RANK(MPI_COMM_WORLD, i,ierr)
  if(i==0) {
     call from_param("verb",verb,.false.)
     iverb=0;if(verb) iverb=1
     call MPI_SEP_SEND_ARGS(n,10,iverb)
  } else call MPI_SEP_RECEIVE_ARGS()
#endif

pro%operator=".R_.D"
  call weimig_init( SLin=weisloN_init, &
		    WCin=weimwcN_init, &
		    FKin=weiwem_init,  &
		    FXin=weissf_init,  &
		    IGin=weihcig_init  )

stat =weimig(pro%adj,pro%add,pro%R,pro%D, &
		    SLop=weisloN, &
		    WCop=weimwcN, &
		    FKop=weiwem,  &
		    FXop=weissf,  &
		    IGop=weihcig  )
#ifdef SEP_MPI
  call MPI_FINALIZE(ierr) 
#endif
  call sep_close();call exit(0)
}

makefile

#LOCATION OF DATA
DIR= /net/koko/data/data_syn/2d/marmousi/
DATA_0=${DIR}/marmcmp.H
DATA=data.H
#TRANSFORM THE DATA INTO TIME,CMPX,CMPY,OFFX,OFFY
#SWITCH TO KM FOR CONVENIENCE
${DATA}:  ${DATA_0}
	Transp plane=23 < ${DATA_0} >a.H
	Pad < a.H >b.H n3out=52 n2out=600
	Window3d < b.H n3=51 |Reverse >c.H which=4
	Cat axis=3 b.H c.H  |Pad n3out=108 >$@
	echo o2=1.725 d2=.0125 o3=-1.275 d3=.025 >>$@
#SWITCH TO KM FOR CONVENIENCE
vel_cor.view.H: ${DIR}/marmvel.H
	Window <  ${DIR}/marmvel.H j1=2 j2=2 |Scale dscale=.001 >b.H
	Cp b.H $@
	echo d1=.008 d2=.008 >>$@
#TRANSFORM DATA TO CMPX,CMPY,OFFX,OFFY,FREQ
freq.H:	${DATA}
	Transf f_min=1 f_max=40 shift2=1 wei=y < ${DATA} >$@
#TRANSFORM THE VELOCITY INTO CMPX,CMPY,CMPZ
vel.mig.H:	vel_cor.view.H
	Transp < vel_cor.view.H plane=12 |Transp plane=23 >$@
#MIGRATE THE DATA IMAGE=cmpx,cmpy,offx,offy,depth
image.H:	vel.mig.H	freq.H mig.P ${BINDIR}/WEImini.x
	${BINDIR}/WEImini.x D=freq.H S=vel.mig.H R=$@ par=mig.P
#THE ZERO OFFSET IMAGE
image.zero.H:	image.H
	Window3d < image.H min3=0. n3=1 |Transp plane=12 >$@
#MAKE THE PICTURE
${RESDIR}/marm.v3 ${RESDIR}/marm.v:	image.zero.H vel_cor.view.H
	Grey < vel_cor.view.H allpos=y bias=1.5 >a.V label1="Depth(km)"     label2="X Position(km)" title=" "
	Grey < image.zero.H  >b.V label1="Depth(km)" label2="X Position(km)" title=" "
	Vppen gridnum=1,2 vpstyle=n < a.V b.V >c.V out=marm.v 
	Vppen  vpstyle=n < a.V b.V >c.V out=marm.v3

Migration parameter file

operation='migration.' operator=".R_.D" #WE ARE TRANSFORMING BETWEEN IMAGE AND DATA
adj=y  #MIGRATION IS THE ADJOINT OPERATION

amy_n=1   amy_o=0.       amy_d=1.       #CMPY AXIS
amx_n=600 amx_o=1.725    amx_d=.0125    #CMPX AXIS
az__n=376 az__o=0.       az__d=.008     #DEPTH AXIS
ahx_n=64  ahx_o=-.175    ahx_d=.025     #OFFSET X AXIS 
ahy_n=1   ahy_o=0.       ahy_d=1.       #OFFSET Y AXIS
aw__n=114 aw__o=0.689655 aw__d=0.344828 #FREQUENCY AXIS

velocity=y #WE ARE USING VELOCITY RATHER THAN SLOWNESS
image_real=y  #WE WANT THE IMAGE TO BE A REAL CUBE
nfk=7 #WE ARE USING 7 VELOCITIES
nzs=47 nfk=15 #NUMBER OF DEPTH AND FREQUENCIES TO HOLD IN MEMORY