Stewart and Schieck (1993) show that a conventional 2-pass 2-D f-k filter fails to provide an axially-symmetric response. They suggest using a true 3-D one-pass filter for specific pass ranges and symmetric results. They also approximate a true 3-D f-k symmetric response by axially rotating a 2-D f-k filter. In this paper a true 3-D f-k filter will be compared with this 2-D rotated filter. During the investigation, it is found that an interpolation scheme is required when rotating a discrete filter to avoid an aliasing problem. A special 2-D filter that has a 2-pass symmetric 3-D f-k response can be defined. This Gaussian shaped filter is applied in two passes and produces a symmetric response, however it has a very gradual cut-off region.
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