Introduction of the Computer Program

copyright  Hongyi Cai  2007
All Rights Reserved

This program runs in MatLab for calculating an overlapped 2D ideal viewing area of text presented 
on multiple visual displays with different sizes, locations, mounting heights, and orientations, 
under different lighting conditions, and viewed by observers located along any viewing plane. 
This program assumes: (a) text is viewed by an identical observer each time to compute a 2D ideal 
viewing area, (b) text presented on the minimum calculating unit area of each display is identical 
in geometries, typefaces, and under uniform lighting conditions, (c) visual displays are rectangular
 without depth. In practice, even on the same visual display, text may be of different sizes and 
the lighting may be uneven. In such cases, the visual display is divided into smaller quasi-uniform
 sections and then individually calculated in the program. 


The flow of this computer program is listed below. 
1.	Enter the number of visual displays.
2.	Enter the observer¡¯s visual acuity.
3.	Enter the text geometries (height, height-to-strokewidth ratio), and its lighting conditions
        (background luminance, luminance contrast percent).
4.	Calculate the on-axis legibility distance of text presented on each visual display.
5.	Enter the geometries (heights, widths, locations on x-y-z coordinates) and initial 
        orientations (?f, ?a) of each visual display.
6.	Find the x-y-z coordinates of the nine calculating points on each display.
7.	Define the viewing plane where the observer¡¯s eyes are located.
8.	Draw the 3D ideal viewing spaces of text presented on each calculating point on each visual 
        display, and then slice them all with the specified viewing plane.
9.	Plot the overlapped 2D ideal viewing area of text presented on all visual displays.
10.	Show the parameters of the 2D ideal viewing area. 


For more information, contact: Hongyi Cai, hongyi.cai@gmail.com