Seeing inside drawings: a system for analysing, conserving, understanding and communicating Leonardo’s drawings

English edition of the catalog of the exhibition held in Vinci, Museo Leonardiano, 15 April 2019 - 6 January 2020, on the occasion of the 500th anniversary of Leonardo's death. The exhibition aims to illustrate the strong link between the Tuscan genius and his hometown, Vinci, through a series of documents from various archival sources. In particular, the 'Landscape' 8P, the first known drawing by Leonardo, has be exhibited, after the careful restoration carried out by the Opificio delle Pietre Dure in Florence, which revealed unseen aspects that were previously unobservable. The catalog reports on all the studies carried out on the basis of these new observations and, more generally, on the figure of Leonardo. The exhibition of the Landscape drawing, dated 5 August 1473, kept in the GDSU of the Uffizi Galleries in Florence, which has been analyzed as a schedule of Leonardo's subsequent activity and it will be the starting point for historical, artistic, geographical and cartographic studies. The Alma Mater Studiorum University of Bologna was asked to create a three-dimensional digital communication artifact of the drawing, by means of an application called ISLe that can allow all visitors and scientist to observe and understand, interpret and imagine the secrets and characteristics of the drawing by Leonardo. The application is therefore proposed as a means of subrogating, investigating, describing and communicating drawings, their methods and their contents, down to the microscopic scale and faithfully reproducing their shape, character and appearance. The digital communicative artifact, using five photographs, reconstructs and restores, digitally rendering, the three-dimensionality of ancient drawings with high color fidelity capability (difference imperceptible to the sight of the expert observer), at a resolution of 50 µm, guaranteeing the restitution of the entire formal quality and surface reflectance of the original. The technical solution developed by the University of Bologna allows to obtain extraordinary results by virtue of a series of specific characteristics: A. An effective 48-bit color acquisition using a linear sensor that avoids the classic interpolation of Bayer pattern sensors, allowing a very wide tonal and color range; B. An LED-based lighting system developed by a technical partner that avoids the typical problems of fluorescent lighting that prevent the acquisition of information at certain wavelengths of light; C. A solution developed to render the surface with micro and macro-scopic fidelity; D. A solution to display the communication artifact in high fidelity using a low-cost rendering engine that is portable to multiple devices (walls, PC monitors, touch tables, tablets, smartphones); E. A visualization interface for visitors to museums and exhibitions based on the usual touch and gestures because they are borrowed from those of smartphones. The essay completely describes this experience by introducing new fundamental discoveries on Leonardo's way of marking and drawing