Local angle domain in seismic imaging

The Local Angle Domain (LAD) is a system of four angles defining the interaction between incident and reflected waves at a specifie image point (element). Two angles represent the spatial direction of the ray-pair normal: its dip (zenith) and azimuth. The two other angles define the reflection angle system. The third angle is the half-opening angle between the incident and the reflected rays. The definition of these three angles is conventional. We define the fourth LAD angle as the azimuth of the ray-pair plane measured in the ray-pair reflection surface. The LAD angles are defined in a rotated local frame, whose "vertical" axis coincides with the background (reference) normal of the reflection surface element. The forward and the inverse transforms between the directions of the incident and the reflected rays and the LAD angles are presented. We consider Isotropie and TTI anisotropic media, pressure waves and converted waves. The presented notation is used within ray-based and wave-equation angle domain migrations.