Ray impedance concept, proposed by Wang (2003), is a physical property measurement, based on pre-stack seismic data, and is an extension of the conventional acoustic impedance computation. After seismic data transformation from the time-offset distance plane to the intercept time-slowness plane, the acoustic ray impedance is implemented along the constant p trace, in the same way as in conventional acoustic impedance computation along a stack trace. The latter is often called the pseudo-logging method.