Accounting for anisotropy in P-wave data processing is now recognized as an important step in improving the quality of seismic data. The quality of final migrated images, prestack gathers, and any attributes derived from the seismic data can all be improved. Commonly, two forms of anisotropy are considered. The first and most common is vertical transverse isotropy (VTI), or the closely associated tilted transverse isotropy (TTI). This anisotropy is often caused by fine layering of sediments, with the layering smaller in scale than the seismic wavelength. In the case of VTI the bedding planes are horizontal, while in TTI they are dipping.