La rappresentazione e il controllo dello spazio: morte e trasfigurazione della Geometria Descrittiva

This article outlines one possible way in which the teaching of descriptive geometry might develop. In the past, this discipline was tasked with inspiring student architects with the ability to imagine, shape and represent space. For almost two centuries this task was carried out with the instruments provided by 15Jh century geometry and academic design. Nowadays, computers complement these traditional techniques of representation with instruments that have enormous operative and expressive potential. These tools are now part and parcel of the work of an architect or engineer and for this reason no school can afford to ignore them. However, computerised representation cannot substitute for descriptive geometry since it constitutes just one stage of its evolution, the most recent. The problem, therefore, lies in harmonising geometric representation and computer representation. A first hypothesis in five parts is outlined below. The first part involves revising the definition of the discipline, its objectives and methods. The revision aims at defining current descriptive geometry as a science that teaches how to mode! three-dimensional forms during representation. This definition fits both descriptive geometry and CAD, emphasising design rather than visualisation which, in the case olC4D, is automatic, while in the case of descriptive geometry it is based on construction. The second part is dedicated to the algorithms of the discipline. A serious revision of the terms and algorithms is necessary, otherwise the student cannot consider descriptive geometry and CAD as being similar. Two examples of innovation are provided: the introduction of the concept of a plane of construction to unite the construction operations of descriptive geometry and those of CAD and the reason behind the construction of a straight line perpendicular to a plane, based on a series of operations and following the Euclidean principles of the discipline. The third part is dedicated to the movement of the images as an excellent way of communicating the shapes of spaces. The fourth part is dedicated to models. In fact, the computer environment relating to modelling can be considered a laboratory in which to experiment the solutions discovered. For example, the graphic construction of the shadow of a spherical niche can easily be tested, while the curve of the fourth order created by the intersection of two cylinders, may be extracted and studied in space. Lastly, the fifth part illustrates the laboratory of lines and surfaces. In fact, computer science permits the range of lines and surfaces normally controlled by descriptive geometry to be increased, thereby allowing the creation of shapes previously impossible.