## 2 Background and Related Works
### Related 3D Reconstruction Cultural Heritage Projects and Frameworks  
The development and wide adoption of 3D scanning technologies has enabled 3D digitization and reconstruction projects to emerge around the world. In this subsection, we discuss the pioneer projects, as well as the most complex 3D reconstruction projects. The most prominent pioneer project focusing on the digitization of cultural heritage is the \"_The Digital Michelangelo Project_\" by [PERSON] et al. [29], which integrates the 3D scanning of 10 status created by [PERSON]. The authors have adopted a wide variety of scanning solutions, including triangulation laser scanners, time-of-flight laser scanners, and digital cameras. As was presented on the project website during their academic year abroad in Italy of a large team including 30 faculty, staff, and students from Stanford University and the University of Washington, the authors have been involved in several side projects such as the Digitizing of the Forma Urbis Romae. The team has scanned the 1163 fragments of the impressive Marble Plan, which is the key source document of ancient Roman topography, measuring 60 feet across, 45 feet high, and 2-4 inches thick. The authors have developed computer algorithms to aid in the reconstruction of the Marble Plan, and they have created a public database that includes all of the 3 Dscanned fragments intended to be used as a public tool for study and research. The authors have managed to approximate only 10% of the original monument, based on the features and fitting between fragments. The results have been presented and published in the Proceedings of the Third Williams Symposium on Classical Architecture, Journal of Roman Archaeology, in 2005. In this case, the accurate 3D reconstruction of the Forma Urbis Romae represents an impossible task, as the existing fragments represent only about 15% of the original marble map, and with the disintegration of the Roman Empire in the fifth century A.D., the Forma Urbis suffered the same fate as the rest of the city; for several hundred years, marble slabs were systematically stripped from the map and used to construct new buildings, or simply burnt in kilns to make lime for cement [30]. As presented by [PERSON] et al., the process of defining the automatic reconstruction of archaeological pieces through the integration of a set of unknown segments is a highly complex problem, and when only a few segments of the original pieces are available, the solutions, exclusively based on computation algorithms, aim to create credible whole restorations. The authors have proposed the use of hybrid human/computer strategies to tackle incomplete 3D puzzles. The method has been applied successful on the fractured pieces belonging to the remains of Roman sculptures at the well-known Merida site in Spain [31]. Most of the 3D reconstructions of cultural heritage projects are focused on archaeological pottery. Ceramic studies have played a central role in the development of archaeology, as ceramics represent by far the largest class of artefacts recovered during the excavations of historical sites. A method intended to assist in the tedious task of reconstructing ceramic vessels shards using 3D computer vision has been presented by [PERSON] and [PERSON] [32]; their proposed method aligns the shards based on a set of 3D weighted curve moments; the main advantage of the proposed method is that it can be extendable to surface markings. For physically reconstructed cultural heritage objects such as ceramics, it is important to capture the photorealistic 3D model. A post-reconstruction of photorealistic 3D models of ceramic artefacts intended for use in interactive virtual exhibitions is presented by [PERSON] and [PERSON] [33]. A recently published review paper by [PERSON] et al. presents the computer-based methods for the classification and reconstruction of 3D high-density scanned archaeology pottery [34].