Abstract: A system in which a three-dimensional image of an object is stored in a data input device in the form of a family of points each defined by digital data representing the x-y-z Cartesian coordinates of the point. Digital signals derived from the data input device are applied through a digital interface to an electronic display on whose face is presented a two-dimensional image of the object constituted by pixels, the positions of which correspond to the x-y coordinates in the family of points. The interface functions to selectively activate each pixel to render it luminous. The selectively-activated luminous pixels are projected into a model space by a lens which is driven to rotate at a constant rate on an axle that is normal to the optical axis of the lens and is parallel to the display face whereby the angle of the lens relative to the face undergoes continuous change.