Completing digital cultural heritage objects by sketching subdivision surfaces toward restoration planning

In the restoration planning process a curator evaluates the condition of a Cultural Heritage (CH) object and accordingly develops a set of hypotheses for improving it. This iterative process is complex, time consuming and requires many manual interventions. In this context, we propose interactive modeling techniques, based on subdivision surfaces, which can support the completion of CH objects toward restoration planning. The proposed technique starts with a scanned and incomplete object, represented by a triangle mesh, from which a subdivision surfaces can be generated. Based on the mixed representation, sketching techniques and modeling operations can be combined to extend and refine the subdivision surface, according to the curator's hypothesis. Thus, curators without rigorous modeling experience can directly create and manipulate surfaces in a similar way as they would do it on a piece of paper. We present the capabilities of the proposed technique on two interesting CH objects.