Dalla matrice geometrica vitruviana alla regola.Aspetti del disegno di architettura nel cinquecento

As of the second half of the XV, to the entire XVI century, Italian architects and treaty writers (such as Fra Giocondo da Verona, Daniele Barbaro, Antonio da Sangallo il Giovane, Giuliano da Sangallo, Palladio, Cesare Cesariano...) studied the topic of the roman (Latin) theater's survey and design. Referring to the De Architectura and therefore to the long issue regarding the interpretation of the Vitruvian geometric matrix, which, as recognized, by tracing a circle and rotating the equilateral triangle enclosed in it generates the proportions of the Latin theater. Such ideal outline was precisely and philologically written by Fra Giocondo da Verona in his illustrated edition of the Vitruvian text (1511). The issues related to understanding, instead, began between the XIV and XV century, when ideal matrix application was tested. We have, indeed, two different explanations that will produce noteworthy and different consequences in structuring the geometric propotions of the architectural plan. The first associates the circle to the semicircular orchestra shape, the second to the cavea dimensions, and so to the entire theatre as a building. The item, familiar to classical age architecture experts, has been matter of frequent interest and produced a wide, specific and huge historiography. There is however, an aspect related to some conclusions of this theoretical research, very innovative for the time, which has not been entirely considered. It is known as the application of the Vitruvian matrix (that seems therefore to acquire indipendent importance on the specific topic of the roman theatre from which it takes origin) to some aspects of the XVI century architectural experimentation. In addition to the cultural breach estabilished between architecture and military engineering, the Vitruvian matrix seems to be proposed again. On the architectural side tha Vitruvian matrix resembles a cultural code for architectural proportioning (and generating geometric shape reference) while for military engineering it represents a formal code therefore a constructive and shaping rule.