The three dimensions of architectural design automation
Authors: Harvey N. Lerman
Venue: Proceedings of the 8th Design Automation Workshop (1971)

Now that the computer era has passed infancy, users of these machines are demanding that a better method be found for representing their output. Those using the computer as a design tool are not content with poring over page after page of uninteresting printout. Visual presentation has provided an answer to this problem, and plotters are now being used to present the designer's thoughts as a series of pictures. These pictures readily present much more information than do many pages of printed output. Instead of having to read columns of X, Y values, the plotter can present these values in graphical form as families of curves. These curves are automatically scaled by the computer and can be presented in various forms. Many items of interest can be read from these plots, such as curve intersections, slopes, ranges, etc. For &ldquo;real world&rdquo; designs, capabilities can be provided for presenting outputs which are functions of more than two variables. To do this, perspective plotting routines can be developed which generate plots of three-dimensional objects on a two-dimensional surface. The user of these routines can specify the position of his eye in three-space and, in effect, view the object at any orientation and size. This provides him with information which he could never get from printed output. In order to make perspective plots more meaningful, a technique can be developed which would identify the lines which are hidden from view by other parts of the plot which are closer to the observer's eye. Once identified, these lines could be eliminated from the plot so that the only lines plotted are those the observer would actually see. As the eye of the observer changes its position, some lines which were hidden come into view, and vice versa. The routines can keep track of the viewing of each line by checking to see if any surfaces are between the line and the observer's eye. If there are any, the line is determined to be hidden. With these tools for representing any object in perspective with the hidden lines removed, an architect could describe a structure he wished to build, and have the computer show it to him in perspective from any and all sides. By the use of &ldquo;clipping&rdquo;, just a portion of the structure could be &ldquo;blown-up&rdquo; and plotted. Also, the architect's view as he walks through his structure could be calculated and displayed. With a library of standards available, the computer would be able to report on the amount of material needed to build the structure, as well as the amount of time and numbers of people needed. Another feature of this system is the ability to calculate projection perimeters and areas. The amount of structure area exposed at some particular line of sight is an indication of the vulnerability of that structure. This area is a very important factor from a military point of view, also. By comparing the projected area of a target with the projected areas of the target's most critical elements, a measure of vulnerability of the target can be obtained. By obtaining the areas projected from several selected viewing points, the expected vulnerability of the target can be calculated.