Figure 3. Comparison of software-generated stacking folds created by swaths A and B. The geometrical parameters for swath A result in a 3-D stacking fold having a value of 20. The 3-D design software achieves that same answer (a). Because swath A honors the even-integer rule, the stacking fold has a constant, non-oscillating behavior over the entire full-fold coverage area (a). The geometrical parameters for swath B cause stacking fold to be a fractional number, 19.25, because swath B violates the even-integer rule. The stacking fold produced by a commercial software design for swath B has a checkerboard pattern consisting of small, abutted areas that have stacking folds ranging from 14 to 22 (b). The spatial distribution and size of each of these distinct stacking-fold areas are such that the average stacking fold over the total full-fold portion of the grid is 19.25. The laterally varying stacking fold produced by swath B makes it difficult to do some data-processing steps (particularly amplitude balancing). The uniform stacking fold created by swath A simplifies data processing and creates confidence in any interpretational process that analyzes variations in reflection amplitudes.