Computer-based methodologies for semi-automatic 3D model generation from paintings

Indexed in SCOPUS. Abstract. Over the last few years, technologies like 3D scanning and Rapid Prototyping provided an extraordinary boost in improving digital and physical reproductions of 3D artworks, like sculptures and historical buildings, all over the world. However, the use of advanced technologies with the aim of realizing 3D models starting from paintings, or photographs, have not been satisfactorily investigated yet. This is a shame, since physical 3D reproduction of subjects represented in paintings, is recognized to be one of the best ways to allow visually impaired people to enjoy such kind of artworks. Though a number of algorithms coming from computer vision science exist to cope with the issue of 3D reconstruction from single images, the specific problem of producing a 3D representation which is targeted at blind people tactile exploration has been only marginally investigated. Moreover, the incomplete, fragmented and often contradictory criteria and methods used all over the world to translate visual images into tactile language, represents barriers to research. Moving from these considerations, this work presents a quite extensive review of the criteria proposed in literature for producing tactile models suitable for blind people. Afterwards, it describes four possible, alternative computer based methods for semi-automatic generation of tactile 3D models (called tactile outline, texturized pattern, flat bas-relief and bas-relief) starting from RGB digital images of paintings. The proposed methodologies to obtain a 3D digital model are based on Image Processing techniques integrated with 3D CAD methods. Once obtained, the 3D digital models have been translated into physical ones by using Rapid Prototyping Techniques and have been submitted to a panel of blind users for assessment. The outcomes of this study contribute new information to the field of visually impaired user-oriented 3D reconstruction and clearly indicates the strategy to be adopted in order to produce a meaningful reproduction of a bi-dimensional piece of artwork.