Abstract: A system is described for rotating a 3D image so that a selected projection thereof is oriented to a chosen angular orientation in a three-dimensional space. The 3D image comprises a plurality of pixels, each pixel identified by a three-dimensional spatial coordinate value and a grey scale value. The system includes a data processor for storing the pixel coordinates and includes circuitry for rapidly altering the pixel spatial coordinate values to accomplish 90.degree. rotations of the 3D image about the axes of three-dimensional space. A pipeline processor is associated with the data processor for rapidly altering pixel spatial coordinate values to orient a 3D image to an arbitrary angle, but only about an axis perpendicular to a rotator plane of the three-dimensional space. The data processor is controlled to modify the spatial coordinate values of the 3D image, to rotate the image through three-dimensional space until the selected projection of the image is coplanar with the rotator plane.