PSDM Tomography is a grid-based tomographic velocity update module. Inputs are a velocity model and picked pre-stack events from OpendTect - VMB. Output is the updated velocity model. The distribution of errors is controlled by the user via a quality volume that specifies the allowed variations. PSDM Tomography comes with the same intuitive job-deck builder as PSDM Kirchhoff and a subset of the Ethos processing system, which is Geokinetics proprietary seismic processing system.