To realize an example of architecture, the object must be described. However, this in itself is insufficient—the process of realizing the object must itself be supported. It is in both these dimensions that computers have been of benefit in the practice of architecture in the 20th century. The use of computers in architectural design has been motivated by a number of factors and driven by others, and has come to reflect the evolution of practice through the last half of the 20th century.
The work of an architect started the century relying heavily on teams of colleagues, employees, consultants, and contractors; by the close of the century, although the practice of architecture was much the same, the picture had changed to include computing tools in almost every team and every practice, drawing the participants closer together through the whole sequence of events leading to the construction of a building. As this change took place, the challenge with the use of computing tools came to be recognized as the challenge of management, not technology.
Describing the Building
Buildings can be described in two ways. They can be described by performance (including quantities), or they can be drawn. Initially, computers were seen as manipulators of data in the simplest sense: calculators and organizers. Thus, when computers were first made accessible to designers, it was largely in the areas of planning and engineering that applications were first undertaken. In these fields, design could be seen to rely on the handling of large data sets as well as the manipulation of equations in the calculation of quantified results. More traditionally, a building is drawn: The geometries of the building are set forth by means of lines, straight or curved, or volumes.
A second application of computers is in the creation and manipulation of graphics. Although computers could be applied to data manipulation and calculation with more simple interfaces of card readers and printers, architectural graphics required more sophisticated user interfaces such as display screens and input devices supporting pointing and drawing. Because the practice of architecture relies heavily on graphic communication, the development of computer graphic devices was highly influential on the spread of computer use in design. The evolution of computer graphics can therefore be considered discretely when reviewing the history of computer-aided architectural design.
Computer Graphics
The first implementation of such systems supporting what we might recognize as a computer graphics system can be found in 1950, when MIT’s Whirlwind computer system was used to support a refreshed vector screen for display of graphics. This system can be considered a first-generation computer, running with vacuum tubes and consuming considerable space and power. Limitations in the interfaces as well as costeffective access to computational systems meant that it was not until 1963 that Ivan E. Sutherland presented Sketchpad, the first full-fledged, operational computer-aided design system. This system ran on second-generation TX-2 computers, using transistors for computation, and refreshed vector displays and light pen for the user interface. Several other implementations of computer graphic systems were developed in academic settings during the early 1960s, leading to the conference “Architecture and the Computer” in 1964.
In late 1964 IBM demonstrated their DAC-1 system to support graphic interaction in automobile design. From the introduction of this system came increasing use of interactive computer-aided design systems by automobile and aerospace firms, so that by end of the 1960s, commercial use of computer graphics was proven, although only in applications that supported high-cost factors. The first computer graphic tool specifically for architectural application was ARK-2, introduced in the early 1970s. General use of computers in architectural design had to wait until the early 1980s, when computer systems had reduced in cost by a factor yet again to make it feasible for large practices to purchase workstations. The final impetus for widespread use of computer graphics came when miniaturization of computer circuits was achieved and computing systems dropped by yet another factor. The personal computer was introduced (1982) and software developers provided tools that could be used in a normal Office environment at a lower cost. As hardware became cheaper and hence more accessible, computers came to be widespread and were common tools in every design practice and activity.
Software developed initially to describe buildings as threedimensional data models, but as workstations became more common, users demanded simpler two-dimensional descriptions for drawing, rather than digital modeling. As personal computers were adopted in practice, the most popular computer tools in practice were drafting systems. As the smaller workstations became more powerful, more complex software could be developed for use on these cheaper platforms, and rendering and presentation software became widely available. Initially capable of displaying only simple forms and colors, these software systems evolved to portray lighting, surface textures, and colors more accurately. By the 1990s such systems were being used in architectural practice to prepare animations of design ideas for presentation to clients, regulators, and potential users.
Traditionally, building designs are communicated visually by two-dimensional descriptions, such as in drawings, as well as by three-dimensional descriptions, such as models. From the start computer graphic systems supported three-dimensional descriptions, although it was not easy to convert these to paper-based drawings. Computer graphics thus came to be categorized into distinct tool sets: drawing tools in which two-dimensional descriptions are created and virtual reality systems in which the user interacts with three-dimensional representations. Some software avoids the problems of full three-dimensional representation with simulating three-dimensional forms by extruding two-dimensional shapes or assembling (as in a card model) two-dimensional drawings in a three-dimensional space. Virtual reality systems have proved to be cumbersome and overly complex for either designers or clients to use and, after 30 years of development, have not yet realized the benefits anticipated in architectural design.
As computers came to be used in design, it was found to be possible to describe forms digitally that may not be apparent or obtainable through manual methods of working. For example, parametric design came to be used—a method in which particular properties of a shape, dimensional or otherwise, could be adjusted as the design progressed. If the parameters were geometric, for example, the shape of a design might change according to other properties such as time or capacity. Using these computational attributes, designers have explored forms that are sufficiently complex to require computer-driven digital output devices such as robotic cutters or rapid prototyping machines. By use of these devices, a more sculptural architecture came to be explored by the end of the century. These sculptural forms also pushed the use of robotics in manufacturing of architectural components.
