Producing an Accurate Crystal Drawing in Any Orientation from a Stereogram
A wholly general method is presented to produce accurate drawings of any crystal in any orientation from a stereogram of the crystal. A standard stereogram is prepared with all faces plotted, and the desired viewpoint is marked. The stereogram is then rotated as necessary to place this mark on the W radius of the net. The stereogram is then held in position, and the viewpoint moved along the W radius to the center of the net. Concurrently, all face poles are moved along their small circles by the same number of degrees and with the same sense of motion as the viewpoint. The poles are now reoriented. Next, appropriate zone circles and their diameters are drawn. Each zone has a zone pole whose direction on the stereogram is parallel to the edges in the zone. A line parallel to this zone pole, called an edge line, is drawn from the net into the adjoining drawing area. Edge lines are drawn for each zone of the crystal, and the crystal drawing is then made by drawing necessary edges to outline faces.