Global Geophysical Services' interactive Eta picker displays the gather and computes the velocity semblance and Eta semblance. The user picks the velocity, computes the Eta semblance, and picks the Eta. The move-out on the gather is updated with each pick. The Eta functions are picked on a coarse grid throughout the volume and used as guide functions for the Eta auto picker. The Auto picker creates an Eta Pick at every In Line and Cross Line Location and at every sample in the volume.