ABSTRACTThe Kirchhoff integral can only be used to propagate wavefields forward. Backward propagation is based on the Porter-Bojarski integral. Both integrals simplify if data is registered on a plane. Transmission and reflection data should be combined to increase spatial resolution. Angles and frequencies should vary as much as possible to cover the largest area possible of the k-space. Migration is identical to diffraction tomography for varying frequencies if the weak scatterer assumption is valid in a constant background velocity medium. Holography is backpropagation and imaging of a monofrequent wavefield. Linear and non-linear inversions improve the migration and tomography results because they consider the data as imperfect. |