mapping-with-two-dimensional-seismic-data_fig4.png|{{figure number|4}}(a) Illustration of ray paths, intervals, and interfaces used to help explain the Dix formula. (b) The Dix formula for calculating interval velocities, which assumes that interfaces are flat and smooth. | mapping-with-two-dimensional-seismic-data_fig4.png|{{figure number|4}}(a) Illustration of ray paths, intervals, and interfaces used to help explain the Dix formula. (b) The Dix formula for calculating interval velocities, which assumes that interfaces are flat and smooth. |