Arte rupestre, metodi di documentazione: storia, problematiche e nuove prospettive

The aim of the Authors of the present contribution is to start a think over the methods of documenting rock art, especially that on open air as the huge patrimony of Valcamonica and Valtellina, in Nothern Italy. The need arises from the different approach of providing documentation between scholars, as the authors, who apply the tracing on transparency sheets called Cristal, and the Soprintendenza ai Beni Archeologici of Lombardy (SAL), who not only regretted that method as not objective, but also prevented it, proposing new applications, as fotogrammetry, Laser scanner 3D, while using old methods as the frottage or the outline of the figures engraved in presentation at Congresses. The long history of the research for the best method of documenting engraved rock art was aimed by the need of the analytical reading of the figures and their relations, to obtain a chronological sequence and a correct interpretation. This lead to consider the tracing on Cristal sheet while enlightening the figures with grazing light by mirror, as the most suitable method to read the engraved figures with the specific purpose of their analytical study. Obviously no regret is put on the use of fotogrammetry or Laser scanner 3D, but they proved to be more useful for conservation needs than for a proper archaeological study. Moreover their application is very expensive, needing a very high level of definition, especially for Laser Scanner 3D, to obtain a trustworthy print of micro scratches and each engraved spot of the figures. So the use of these methods imply very limited achievement of documentation for their great expense, while Valcamonica and Valtellina rock art need a large campaign of documenting. The authors consider the lack of published archaeological study provided by fotogrammetry and Laser scanner 3D, after more than ten years of applications, as the best prove of the difficulties of analysis by these methods. So concluding they consider the tracing as a real archaeological drawing, especially useful for the study of every single part of the rock engravings, which enriches the documentation provided by the new methods, without damaging the rock at all.