Most VGTs you will design contain text, or at least captioning. You should construct your captions and
lettering large enough for normal viewing by persons of normal vision. Most lettering should be
uppercase, as uppercase letters are larger and easier to read at a distance.
To find the minimum letter size for a 7 1/2 inch projectional, you must know two factors; the distance
in feet from the projector to the screen, and the distance in feet from the screen to the farthest viewer.
With this information, and using a nomograph (see figure 2-1), you can find the recommended
minimum letter height in inches as follows.