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![]() | IWAVE Structure and Basic Use Cases | ![]() |
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Figure 10 displays the migration of the single
Born ``shot'' gather (really, OBS receiver gather) located at
m from
the left edge of the model. No effort has been made to remove the
low-frequency noise caused by the sea bottom reflection.
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migr12000
Figure 10. Reverse-time migration of Born data from Figure 9. |
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The parameters required for this job are
deriv = 1 adjoint = 1 nsnaps = 10 csq = ../csq_4layer.rsf csq_b1 = ../migr12000.rsf source = ../wavelet12000.su data = ../born12000.su
The adjoint key flags the adjoint computation. The checkpointing algorithm requires allocation of workspace for checkpoints (copies of wavefield Cauchy data, consisting of all dynamic arrays). The number of checkpoints allocated is the value for key nsnaps. The appropriate number of checkpoints depends on the number of time steps. Reasonable numbers to achieve a cost ratio of adjoint to forward computations of around 5 are
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