3-d visualization and animation of architectonic elements for prehistoric megalithic temples of the island of Gozo: the temple of Ggantija

Laser scanning can now be defined without doubt as the newest frontier in the field of survey technique, and recent technological developments of instruments and processing software have encouraged the introduction of this technique in the world of applications connected to archaeological site and other related disciplines. The temple of Ggantija on the island of Gozo was considered to be representative of the entire series of temple complexes due to their particular architectural characteristics, their stage of evolution and form of deterioration, both material and structural. The survey was conducted by the use of the local geodetic network in the different phases: • Topographic survey • 3D laser scanner survey • Photographic Survey: both traditional and digital pictures will be taken in order to fully documentation internal and external surfaces of the site. The treatment and analysis of data collections was divided into the following sub-stages: elaboration and compensation of close polygonal, thickening polygonal and direct measurements; elaboration and compensation of altimetric network; linking of the above data with the existing Maltese national networks; elaboration of laser scanner positions and absolute orientations; elaboration of points coordinates for georeferencing and linking the point clouds coming from laser; final data verification end quality control; analysis of laser measured point clouds, for filtering and subsequent elaboration; scanning orientations and subdivision into “islands” (internal rooms and external sides); analysis of laser measured point clouds over the grid determined by the topographic survey.; modelling of the Archaeological site, elimination of noises and metric "pollution" by statistics and verification; accentuation and reduction of triangles on areas interested by complex geometries; triangles transformation into complex surfaces (mesh); model checking by topographic points; mapping of digital photocolors covering all the surfaces of the site. The digital model will be cut by vertical and horizontal section plans at heights requested by customer 2D graphic editing of the plans, sections and elevations. Finishing of vertical sections (sections and views) using the mapped model created by rendering calculated, generating contours lines from the 3D model; of a light model (low density model) of the laser scanner data using the filtering tools of the software package; of an virtual animation of the high density model; of a mapped VRML (Virtual Reality Modelling Language) model for a web interactive and hypertestual navigation, using the low density model. This part of the study was aimed at defining the architectural characteristics and mode of construction of this monument.