Il rilievo “automatico” del colore: nuove tecnologie a supporto della lettura cromatica per il restauro dell’edilizia storica

The introduction of optical active sensors in automatic survey equipment has significantly transformed the traditional approach for the acquisition and understanding of the color value and properties of architectural buildings. That of chromaticity is, in fact, one of the main aspects of building practice; an essential component of a whole surface material that, as such, should be approached and treated. And technological innovation is moving in this way, not only by implementing the specific skills of "surveyors / architect restorers" (now also photographers and experts in digital imaging), but also putting at their disposal other instrument for the study of color and the material analysis of historic buildings. Furthermore, what once was delegated to the interpretation of the operator during the graphic restitution, phase during which the geometric and architectural survey was enhanced by important information about surface colors, today, with the latest generation of laser scanners equipped with integrated coaxial cameras, acquires new meanings and temporalities. Nowadays, the mapping of point clouds obtained from laser scans by digital photographs is a consolidated technique. However, there are many professionals involved in this methodology and long and complex are the related operating phases. New tools recently put on the market permit a simplification of these actions: simultaneously providing (in situ), not only 3D metric information but also colorimetric and spectral data. This paper aims to show how the use of modern 3D technologies could be considered as a valuable additional supporting tool for the knowledge of historical architecture, last but not least for cataloging colors and identifying changes and degradation phenomena. It intends also to highlight how this cost and time effect process allows extending the survey of color not only to monumental architecture, but also to less prestigious building types.