3D Survey and Virtual Reconstruction of the G-Group

In the last decade the use of 3D acquisition techniques in the archaeological field has allowed to widen the scope of the geometric survey process, providing high resolution reality-based digital models capable to be linked with different historical documentations, greatly improving the conventional bi-dimensional hand-made survey with a consequent gain of knowledge for the archeologists. Another possible output, supported both by reality-based models and historical data, can lead to the generation of suggestive 3D digital reconstructions of architectures not anymore existing, made lively through Computer Graphics. These can be useful for a careful interpretation of the existing ruins but sometimes they might also be capable to suggest new archaeological discoveries. A weak part of the latter process is represented by the possible lack of scientific reliability on the reconstructed model, due to the actual disjunction between the modelers producing the final computer graphics output, and the archeologist owning the knowledge for creating the appropriate reconstructive hypotheses. The methodology here proposed is based on a first extensive 3D documentation of the site in its current state, followed by an iterative interaction between archaeologists and digital modelers, leading to a progressive refinement of the reconstructive hypotheses. The starting point of the method is the reality based model, that, together with ancient drawings and documents, is used for generating the first reconstructive step. Such rough approximation of a possible architectural structure can be annotated through archaeological considerations that has to be confronted with geometrical constraints, producing a reduction of the reconstructive hypotheses to a limited set, each one to be archaeologically evaluated. This refinement loop on the reconstructive choices is iterated until the result become convincing by both points of view, integrating in the best way all the available starting data. This paper describes this approach to the digital reconstruction problem has been verified on the ruins of five temples in the Mỹ Sơn site, a wide archaeological area located in central Vietam. Created by the ancient Cham civilization active in Vietnam from 7th to 18th century, it has been listed as UNESCO World Heritage in 1999. Mỹ Sơn area contains a reasonably well preserved system of 78 Cham Temples, some of them destroyed by the nature in the last centuries. The integration of 3D surveyed data and historical documentation has allowed to support a digital reconstruction of not existing architectures, developing their three-dimensional digital models step by step, from rough shapes to highly sophisticate virtual prototypes. The 3D acquisition and modeling of a specific set of five temples, indicated by the archaeologists as “G group”, is here presented and methodologically discussed