Digital Restoration of Damaged Cultural Relics: A Case Study on Chinese Unearthed Bronzes

Bronzes are one of the Chinese cultural treasures.However,most unearthed bronzes inevitably miss some pieces with types of patch-like,crossing patch-like and structural ones.With the great improvements of the 3D reconstruction and laser scanning techniques,the usage of the 3D cultural relic models with the high fidelity for the cultural relic repairing has been received a widely attention.The missing pieces on bronzes are usually with different types and with complicated geometries and topologies.Therefore,this paper seeks to complete the missing pieces based on the morphological characteristics of the bronzes themselves.Key technologies have been studied,including the following items.For patch-like missed pieces,the symmetry of models with missing data is first detected,and the missing pieces are then filled based on global symmetric transformation to obtain initial making-up results.Due to the approximate symmetry of the bronze surface,the initial result is often incoherent with its surrounding surface.Therefore,it is necessary to extract local reliefs on the surface,and naturally make reliefs on the initial result coordinated with the ones on the holes’boundaries based on existing curves matching techniques.For crossing patch-like ones,we design the trend of the Euler spiral of the missing block edge and study the similarity matching technique of the data inside and outside the missing block,and use the coarse-to-fine and feature-sensitive matching method.For the structural missing ones,a surface editing technique with high efficiency and good interactive performance is introduced to complete the bronzes.Our research can provide technical supports on the digital restoration of the bronzes.