When either 2D Stereopair, OpenGL Stereopair, OpenGL Quad Stereo or Direct3D Stereo Drawing mode is selected, two images of the structure will be drawn. The left or left-eye image will be rotated by the stereopair Rotation angle clockwise from the normal orientation, and the right-eye image will be rotated the same amount counter-clockwise. If shading is active the illumination vector will be rotated along with the structure. The stereopair rotation angle is typically about 3 degrees, although the proper angle may vary depending on the perspective distance, the actual viewing method, etc.
If the hard copy of stereopairs is to be viewed directly or with a small viewer, a frame size in the dot-matrix or pen plot of 4 to 5 inches across will give a distance between the two images about equal to the normal interocular distance.
Few people can directly view a stereo pair as shown on the full screen because the images are considerably further apart than the eyes. However, if a negative rotation angle is used, some people can view the image by crossing their eyes.