In this paper we present a technique for the interactive control and display of static and dynamic 3D datasets. We describe novel ways of tri-linear interpolation and gradient estimation for a real-time volume rendering system, using coherency between rays. We show simu lation results that compare the proposed methods to tra ditional algorithms and present them in the cantezt of Cube-B, a special-purpose architecture capable afrender ing 5123 16-bit per vozel datasets at over 20 frames per second.