ABSTRACT:This paper exploits the potential of dense multi-image 3d reconstruction of destroyed cultural heritage monuments by either using public domain touristic imagery only or by combining the public domain imagery with professional panoramic imagery. The focus of our work is placed on the reconstruction of the temple of Bel, one of the Syrian heritage monuments, which was destroyed in September 2015 by the so called "Islamic State". The great temple of Bel is considered as one of the most important religious buildings of the 1st century AD in the East with a unique design. The investigations and the reconstruction were carried out using two types of imagery. The first are freely available generic touristic photos collected from the web. The second are panoramic images captured in 2010 for documenting those monuments. In the paper we present a 3d reconstruction workflow for both types of imagery using state-of-the art dense image matching software, addressing the non-trivial challenges of combining uncalibrated public domain imagery with panoramic images with very wide base-lines. We subsequently investigate the aspects of accuracy and completeness obtainable from the public domain touristic images alone and from the combination with spherical panoramas. We furthermore discuss the challenges of co-registering the weakly connected 3d point cloud fragments resulting from the limited coverage of the touristic photos. We then describe an approach using spherical photogrammetry as a virtual topographic survey allowing the coregistration of a detailed and accurate single 3d model of the temple interior and exterior.

No abstract

Abstract:In order to improve the observation capability in one of the most active volcanic areas in the world, Mt. Etna, we developed a processing method to use the surveillance cameras for a quasi real-time mapping of syn-eruptive processes. Following an evaluation of the current performance of the Etna permanent ground NEtwork of Thermal and Visible Sensors (Etna_NETVIS), its possible implementation and optimization was investigated to determine the locations of additional observation sites to be rapidly set up during emergencies. A tool was then devised to process time series of ground-acquired images and extract a coherent multi-temporal dataset of georeferenced map. The processed datasets can be used to extract 2D features such as evolution maps of active lava flows. The tool was validated on ad-hoc test fields and then adopted to map the evolution of two recent lava flows. The achievable accuracy (about three times the original pixel size) and the short processing time makes the tool suitable for rapidly assessing lava flow evolutions, especially in the case of recurrent eruptions, such as those of the 2011-2015 Etna activity. The tool can be used both in standard monitoring activities and during emergency phases (eventually improving the present network with additional mobile stations) when it is mandatory to carry out a quasi-real-time mapping to support civil protection actions. The developed tool could be integrated in the control room of the Osservatorio Etneo, thus enabling the Etna_NETVIS for mapping purposes and not only for video surveillance.

The introduced research is about 3D modeling technique that can be considered as an assembly point of photography, topography, photogrammetry, and computer graphics. The chapter present survey methods based on spherical panoramas produced by image stitching techniques, which are proved efficient in order to obtain a high metric quality. It is an interactive survey system to generating 3D models of architectural structures and urban scenes. Photogrammetric fundamentals are applied using two different approaches to obtain the 3D model: the first one is by using texture-mapping techniques in the way of creating the virtual models; while the second is by using parametric visual programing process.

In summer 2010, during a study journey, Fangi has got to realize photographic coverage of some UNESCO sites of Syria, according to the technique of panoramic photography. Those shoots have become important as a result of the outbreak of civil war, as documents useful for documentation, survey, and for any possible restoration of the monuments damaged or destroyed by war. It 's the case of the millenary minaret of Aleppo. With the technique of spherical panoramic photogrammetry, developed by Fangi, it was possible to carry out a survey of quantities and the virtual reconstruction of the minaret. So it was also done for the other UNESCO documented monuments as the Roman theater of Bosra, the great mosque of the Umayyad in Damascus, and the walls of the citadel of Aleppo and finally the minaret of the great mosque in Aleppo. The detailed description of the project will be made in the work that will be presented in the next international conference UID (XXXV International Congress of Teachers of Representation) to be held in October in Matera, Italy, on Cultural Heritage Sites. The serious damage that the civil war has caused to the Syrian heritage make the documentation of these monuments by UNESCO a key element for their conservation, possible restoration and memory.