In architecture offices today, you rarely find a drafting board with a parallel bar, rolls of tracing paper, measuring scales, triangles, drawing templates or boxes of pencils and markers. Instead you see a workstation with a flat-screen monitor, keyboard and mouse. Many designers use computers for "drawing" everything: diagrams, preliminary design studies, three-dimensional views and construction documents. Produced on large-format printers, drawings can even be made to look like hand-drawn sketches.
Computer-aided-design (CAD) has transformed architectural design methodology, not because it eliminates manual drawing, but because it allows architects to compose stacks of drawings at every stage of design. Architects can show clients countless design variations, create realistic renderings and graphic simulations, and produce detailed construction documents.
Once preliminary design studies - site plan and massing studies, floor plan layouts, sections and elevations - are undertaken and a preliminary digital model is created, the architect can obtain three-dimensional views, including animated walk-throughs or fly-throughs. The designer also can modify any part of the project, whether a house or a high-rise, and CAD software can automatically edit and update all parts of the design affected by the modification.
CAD software can manage a vast amount of layered data, keeping track of and coordinating all digital model components and systems, such as the structural skeleton, windows, doors, interior partitions, floor finishes, ductwork and plumbing. These programs can alert the designer if components conflict geometrically and can instantly recompute dimensions, floor areas and material quantities.
It gets even better. When a design is finalized and fully defined in a three-dimensional digital model, CAD programs can print annotated, two-dimensional drawings for bidding, building permits and construction. For highly complex designs that cannot be adequately represented and interpreted using conventional documents, the digital model itself can become the primary documentation.
Architect Frank Gehry's work epitomizes and necessitates this approach. His design concepts begin as sketchbook squiggles or crumpled paper and are ultimately transformed into volumetrically complicated, expressively curvaceous buildings impossible to draw. The Guggenheim Museum in Bilbao, Spain, the Walt Disney Concert Hall in Los Angeles, the Stata Center at M.I.T. and the Jay Pritzker Pavilion in Chicago's Millennium Park could not have been designed and constructed without using digital models.
Contractors for these projects directly accessed Gehry's digital models, not conventional drawings. That was the only way they could calculate and price the enormous quantities of materials and labor necessary to fabricate and install the thousands of steel structural members and metal panels that make up the complex exterior skins of these buildings. Only with advanced computer technology could Gehry's idiosyncratic approach to design have evolved and his projects been implemented.
Yet if every architect emulated Gehry's expressive approach, a lot of bad architecture would result. This is because CAD can seductively induce "I can, therefore I shall" thinking. Because architects can digitally model almost any form they can dream up, CAD can lead to excessively complex, overwrought building designs - form for form's sake. Such CAD-gone-wild buildings may be inappropriate for their sites, functionally inefficient, difficult to construct, way over budget and perhaps even ugly.
During the preliminary design phase, CAD programs also can yield machine-printed drawings that make a schematic design idea appear more precise, refined and resolved than it really is. Before CAD, concepts drawn by hand often were sketchy and loosely delineated with wavy or fuzzy lines laid down by soft pencils, felt-tip pens or charcoal. The art and technique of manual drawing ensured that schematic ideas looked schematic.
The computer is a powerful tool, but still just a tool that must be used properly. Designers who never draw manually still must engage in critical thinking and rational invention, as if they were drawing and designing by hand, even though their hand grasps a mouse instead of a pencil.
Roger K. Lewis is a practicing architect and a professor emeritus of architecture at the University of Maryland.