This work benefitted from anti-aliasing discussions I had with Jon Claerbout, Francis Muir, Dave Nichols and Dimitri Bevc. Dimitri and Jon helped improve the paper with their thorough proofreading. Halliburton Geophysical Services kindly donated the 3-D salt intrusion data used in this example, and Mihai Popovici volunteered to unload the data from 6250 tapes to disk.