The recent upgrading of laser scanning devices has led to a set of new surveying techniques for civil engineering and environmental analysis.The terrestrial laser scanner allows complete and dense 3D digital models of the surface of any object to be reconstructed. This is very useful for natural hazards and risk assessment where morphological investigation is a starting point to evaluate stability properties. In the case of disaster management, a 3D model is useful to acquire and monitor emergency situations. Field acquisitions, with laser scanner devices are, in addition, very fast and they are made in safe conditions. However, particular attention must be paid during the acquisition, processing and modeling phases.LIDAR data often include elevated noise (usually gross errors and outliers) that has to be removed with opportune techniques before starting the 3D registration and modeling. In addition, 3D contexts usually have very complex shapes that cannot be recorded with sufficient resolution with a single scan. For this reason, two or more scans must be taken from different points of view of the same object, in order to eliminate shaded areas.To obtain the final 3D model of the object it is therefore necessary to align and geo-reference the single scans using suitable registration techniques.The integration of DDSM geometric data (e.g. the point cloud acquired by using the laser scanner) with image radiometric data allows a new concept of the Solid Image to be obtained.

ABSTRACT:Documentation of archaeological and cultural heritage sites is at the heart of the archaeological process and an important component in cultural heritage research, presentation and restorations. In 2012 the Superintendence of Cultural Heritage of Aosta Valley -IT (Soprintendenza per i Beni e le Attività Culturali della Region e Autonoma Valle d'Aosta) carried out a complex archaeological excavation in a composite archaeological context, situated an urban background: the Aosta city centre. This archaeological excavation has been characterized by the classical urban archaeological issues: little space, short time, complex s tratigraphy. Moreover the investigations have come out several structures and walls that required safety and conservation measures. Ad hoc 3D solutions carried out a complete 3D survey of the area in 10 different time/situations of the Archaeological digs, chosen in collaborations with the archaeological staff. In this way a multi temporal 3D description of the site has been provided for the archaeo logical analysis and for the project of the restorations activities. The 3D surveys has been carried out integrating GPS, laser scanner technology and photogrammetry. In order to meet the needs of th e site, and its complex logistics and to obtain products that guarantee the high quality and detail required for archaeological analysis, we have developed different procedures and methodologies: hdr imaging for 3D model with correct, consistent and uniform colours, noise filtering and people filtering, for the removal of interference between laser instrument and object of the survey, Advanced laser scanner triangulation, in order to consider both artificial and natural tie points, for a correct registration of a huge am ount of scans. Single image orientation on 3D data, in order to integrate the laser data with data coming from digital photogrammetry (faster on the field than the laser scanner survey, than used in certain situations) The results of all these methodologies and procedures will be presented and described in the article. For the documentation of the archaeological excavations and for the management of the conservation activities (condition assessmen t, planning, and conservation work). Ad Hoc 3D solutions has costumized 2 special plug-ins of its own software platform Ad Hoc: A d Hoc Archaeology and Ad Hoc Conservation. The software platform integrates a 3D database management system. All information (measurements, plotting, areas of interests…) a re organized according to their correct 3D position. They can be queried using attributes, geometric characteristics or their spatial pos ition. The Ad Hoc Archaeology plug-in allows archeologists to fill out UUSS sheets in an internal database, put them in the correct locatio n within the 3D model of the site, define the mutual relations between the UUSS, divide the different archaeological phases. A simple interface will facilitate the construction of the stratigraphic chart (matrix), in a 3D environment as well (matrix 3D). The Ad Hoc...

Metric surveys are a key component in Cultural Heritage. Metric surveys are in fact a basic input for a wide range of activities, from documentation to study, from restoration to valorization, that rely on the current condition of the monument. In recent years, laser scanning and, more recently, digital photogrammetry offered new perspectives, widening the perspectives of 3D Cultural Heritage recording. Digital technologies provide new ways to collaborate, record excavations, and restore artifacts, and in such a way they are transforming the way Cultural Heritage practitioners (researchers, archaeologists, curators) work. This paper attempts to review the methods for 3D digitization that are today available and discuss the possible use of 3D models beyond the pure extraction of reliable and accurate measures.

Metric surveys have a key role in managing Cultural Heritage. They are needed for a wide range of activities like documentation, study, restoration, and valorization. The importance of the 3D description of objects is widely accepted considering costs/benefits ratio and the opportunities it offers. In recent years, laser scanning and digital photogrammetry offered new perspectives, widening the options in 3D CH recording. Scientific research tends to see their integration as the best approach to CH description. 3D surveys are offering extra opportunities respect to the traditional production of metric supports as 3D models are the ideal base for true 3D information systems and open the way to immersive virtual reality environments. Digital technologies provide new ways to collaborate, record excavations, and restore artifacts in such a way, they are transforming the way CH practitioners work. This chapter attempts to review the methods for 3D digitization that are today available and discuss the possible use of 3D models beyond the pure extraction of reliable and accurate measurements.

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