Automatic creation of bas-relieves from single images

摘要

When we think to bas-relieves it is natural to compare them with sculptures, because they share some common properties such as techniques, materials and shapes. However, from a different perspective, bas-relieves have even deeper connections with other bi-dimensional forms of art, such as the frescoes; both have been used to decorate walls surfaces, although bas-reliefs enabled different perspective of interpretation. Bas-relieves, in fact, extend themselves in the three-dimensional space and are therefore able to provide more information compared to an image representing the same scene; moreover, and not less interestingly, they are also enjoyable by users with special needs, such as blind people, that are able to explore their surfaces by means of their sense of touch. For this reason, many attempts have been made in the past to realize bas-relieves representing transpositions of bi-dimensional artworks such as images in order to improve their accessibility. Commonly these transpositions are manually made since manual procedures allow to retain the full control of the final result. The introduction of ICT tools such as 3D modeling and printing has allowed to simplify this process which however still results long and time-consuming, often aimed to one single specific case. In this paper we present an automatic system to enable a fast and massive production of 2.5D models, suitable to be transformed into simplified bas-relieves, starting from a single image, and providing an interactive editor in order to refine the results of the automatic reconstruction, designed for users having no special technical skills. The resulting digital models can be (optionally) refined with 3D modeling tools and directly used in Virtual Reality applications, for instance for educational purposes, or physically reconstructed as actual bas-reliefs to enable access to blind people. The paper details the methodology, the algorithm and presents the results obtained.