STATE OF THE ART

Geomatics techniques have been successfully used in several applications requiring accurate digital reconstructions. The opportunity to follow a scalable approach, starting from the environmental level till the local one, makes Geomatics an unique source of information in projects for landscape and built heritage knowledge, conservation, valorization and management.

It is well known that digital information, including cartographic data and information at the level of the building (local level), can be captured with sensors mounted on satellites, airplanes, UAV platforms, till the ground level. Photogrammetric and laser scanning methods are then applied to turn raw observations into digital products for the different specialists involved in the project.

This has a direct connection to the Digital Agenda for Europe (DAE), which promotes the use of digital technologies to stimulate Europe's economy. DAE is the first of seven initiatives under the Europe 2020 strategy for smart, sustainable and inclusive growth. The overall aim of this initiative is “to deliver sustainable economic and social benefits from a digital single market based on fast and ultra-fast internet and interoperable applications”. In recent years, the need of a reliable production and exchange of digital information has become even more important, especially with the introduction of the European Union Public Procurement Directive 2004/18/EC (EUPPD), approved on 15 January 2014 by the European Parliament. EU member states have two years to implement the Directive into national legislation, becoming full operative in 2016. Public procurement plays a key role in the Europe 2020 strategy as one of the  market-based instruments to achieve smart, sustainable and inclusive growth while ensuring the most efficient use of public funds. 

Geomatics information is directly affect by the requirements of the Directive and, at the same time, it assumes a fundamental importance with an increasing demand of innovative methodologies to collect, process, validate and exchange digital information for simplifying the public procurement regime. In this sense, a multi-resolution approach based on surveying techniques able to produce 3D models offers the robust connection expected at different levels and for different specialists. Built Heritage constitutes a specific field to be investigated, for its peculiarities in respect to the new constructions.

A reliable digital 3D model, if rigorously built, can be used in different fields of application: from BIM to FEM, from documentation towards conservation to dissemination of our heritage. Usable virtual copies or physical replicas can be employed for real and virtual restoration, for visual and tactile exploration. These models constitute a new approach that can join metric data, semantic information and object attributes towards a collaborative project, as stated also by EUPPD. The change of scale, from the building to district to city till the landscape level, can be furthermore seen as a progressive approach towards Geographic Information System (GIS) based information.

Today, 3D models, particularly BIM and GIS, are often used as separated tools, notwithstanding their common base consisting in spatial information with georeferenced entities described by attributes. BIM-GIS integration is not only expected, but mandatory to ensure a convergence of multidisciplinary interests. In this context, Geomatics methods for data collection and processing are the main source of information for the generation of reliable digital 3D models. This is a fundamental aspect, especially for the increasing availability of low-cost software on the commercial market, sometimes able only to provide “crude” reconstructions without metric integrity, that do not match the rigorousness of classical photogrammetric methods. Indeed, the new processing algorithms developed in recent years can significantly automate the different phases of the 3D reconstruction pipeline. On the other hand, this improved automation comes at a cost, that is a scarce attention to the reliability of the output, which cannot be neglected in the case of real metric application. Methods to evaluate the quality of the output must therefore be developed to validate if the achieved out has certified accuracy, demonstrating if it can be useful for productive work in different field of application.