True Three-Dimensional Display Of Computer Generated Images
Hank Stover, John Fletcher, Jean P. L. Ebbeni, Andre Monfils · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 1983
The display of data in three dimensions overcomes the ambiguity often found in two dimensional displays. A truly objective examination of the display data is allowed while two-dimensional displays require a subjective interpretation of what might exist in the Z direction. Data can occupy a volume of 20 X 25 X 30 centimeters since SpaceGraph allows the display of data in a volume filling manner. The display volume is generated by observing the reflection of a CRT in a circular mirror. The mirror is flexed about a rubber hinge located on a concentric circle several inches from the edge. By exciting this assembly with a hi-fi woofer, the mirror is caused to vibrate and takes on concave and convex optical shapes thus varying the focal length. The varying focal length causes the image of the CRT to sweep out apparent distance in Z of about 30 centimeters. By plotting points on the CRT in X and Y, these points permit us to draw vectors which can describe a wide variety of three-dimensional objects, such as molecules, mechanical subassemblies or total assemblies such as aircraft and ships. In the vector mode, SpaceGraph provides 23 meters of vectors which can appear in as many segments as required by the object being displayed. The three-dimensional display can also be used in a second mode which can be called the image mode. In this mode, X and Y are controlled to generate a raster much like one generated in a conventional home TV. While the raster is being swept, brightness is varied to provide an image in gray shades. As this process takes place, the Z is continuously swept by the mirror as in the vector mode and a volume filling image is created. This mode appears to be of particular interest in computer-aided tomography and to seismologists. Computeraided design, ultra sound analysis, anti-submarine warfare and air traffic control are other applications or views of science which appear promising for 3-D displays.