1. A three-dimensional spatial image system comprising: A. a data input device having stored therein a three-dimensional image of an object in the form of a family of points, each point of which is defined by digital data representing x-y-z Cartesian coordinates of that point, B. an electronic display on whose face is presented a two-dimensional image of the object defined by activated luminous pixels whose positions correspond to the x-y Cartesian coordinates in said family of points; C. a lens rotating at a constant rate on an axle normal to its optical axis and parallel to the display face whereby the angle of the lens relative to the face undergoes continuous change in the course of each revolution thereof, the lens projecting each of the luminous pixels into a model space in front of a viewer to produce a corresponding luminous dot at a location therein that depends on the lens angle; D. a sensor associated with the rotating lens to produce a reference pulse each time the lens is at a predetermined angle whereby a reference pulse is produced during each revolution of the lens; and E. a digital interface connecting the data input device to said electronic display, said interface being constituted by a computer functioning in response to said reference pulse to compute the changing angles assumed by said lens in the course of each revolution to produce lens-angle digital signals and to process the x-y-z digital data signals received from the input device in relation to the lens angle digital signals to cause activation of the related pixel in the electronic display at the instant at which the lens angle is such as to project the corresponding luminous dot into the model space at a location in accordance with the z-coordinate whereby rotation of the lens results in a family of luminous dots in the model space at respective x-y-z locations therein to create a three-dimensional spatial image of the stored object.