** Next:** CONCLUSIONS
** Up:** THE SPLIT-STEP FOURIER MODELING
** Previous:** A 2-D example

The three dimensional model is built for a linearly varying velocity
in all three coordinates: *v*(*x*,*y*,*z*)=*v*_{0}+*ax*+*by*+*cz*.
The reflection model is just a diffractor situated inside the velocity cube.
The size of the modeling baby-grid (64x64x256) was imposed by the amount of
memory available on the SEP Connection Machine. The size
of the available memory is also the reason why
I have not implemented absorbing boundaries for the 3-D
algorithm. With
20 gridpoints on each side of the 64 points mesh the active area
will be only 24 points!
Figure displays time slices through the 3-D cube
of diffraction data obtained using PSPI modeling while
Figure displays time slices through the 3-D cube
of diffraction data obtained using Split-Step modeling.
**pspi3Dtimes
**

Figure 7 Time slices through the 3-D diffraction cube (64x64x256) output
of the **PSPI** modeling program. The wraparound is due
to non-absorbing boundaries.

**split3Dtimes
**

Figure 8 Time slices through the 3-D diffraction cube (64x64x256) output
of the **Split-Step** modeling program. The wraparound is due
to non-absorbing boundaries.

** Next:** CONCLUSIONS
** Up:** THE SPLIT-STEP FOURIER MODELING
** Previous:** A 2-D example
Stanford Exploration Project

11/18/1997