Current seismic interpretation often amounts to taking colored pencils and enhancing aspects of a computer-generated image. Seismic interpretation is entering an era in which the interpretation will all be done on a video screen. The basic reason is that a sheet of paper is only two-dimensional, while most reflection data is three-dimensional. Modern 3-D surveys really record four-dimensional data. A video screen can show a movie. The operator/interpreter can interact with the movie. There are things I would like to show you, but I cannot show you in a book. Seismic data or even a blank sheet of paper has texture. When a textured object moves, you immediately recognize it. But I couldn't show it to you with pictures in this book. (Imagine a sequence of pictures of a blank sheet of paper, each one shifted some way from the previous one). The perception of small changes is blocked by any eye movement between pictures. Astronomers look for changes in the sky by rapidly blinking between looking at photographs taken at different times. Our eyes are special computers. Movies often show ``where something comes from,'' enabling us to notice the unexpected in the general ambiance.
Most seismic interpretation is done on stacked sections. The original data is three-dimensional, but one dimension is removed by summation. Theoretically, the summation removes only redundancy while it enhances the signal-to-noise ratio. In reality, things are much more complicated. And much more will be perceptible when summations are done by the human eye (just by increasing the speed of a movie). There will be two generations of seismic interpreters--those who can interpret the prestacked data they see on their video screens--and those who interpret only stacked sections.