Method and apparatus for preemptive volume rendering

A method and apparatus for performing preemptive rendering of a 3D dataset is disclosed. Some rendering engines are too slow to render a large dataset quickly. In this patent, a list of possible views is generated. For each possible view includes a viewing position and viewing angle. For each possible view, rendering of a 3D dataset is performed to generate a corresponding preemptively rendered image for said each possible view. Each possible view and corresponding preemptively rendered image are stored. A head display unit's position and orientation are tracked and at a time epoch when said head display unit's position and orientation correspond to a possible view in said list of possible views, the corresponding preemptively rendered image is displayed.