Automated pebble mosaic stylization of images

Digital mosaics have usually used regular tiles, simulating the historical "tessellated" mosaics. In this paper, we present a method for synthesizing pebble mosaics, a historical mosaic style in which the tiles are rounded pebbles. We address both the tiling problem, where pebbles are distributed over the image plane so as to approximate the input image content, and the problem of geometry, creating a smooth rounded shape for each pebble. We adapt SLIC, simple linear iterative clustering, to obtain elongated tiles conforming to image content, and smooth the resulting irregular shapes into shapes resembling pebble cross-sections. Then, we create an interior and exterior contour for each pebble and solve a Laplace equation over the region between them to obtain height-field geometry. The resulting pebble set approximates the input image while presenting full geometry that can be rendered and textured for a highly detailed representation of a pebble mosaic

Using image-based modelling (SfM-MVS) to produce a 1935 ortho-mosaic of the Ethiopian highlands

Approximately 34,000 aerial photographs covering large parts of Ethiopia and dating back to 1935-1941 have been recently recovered. These allow investigating environmental dynamics for a past period that until now is only accessible from terrestrial photographs or narratives. As the archive consists of both oblique and vertical aerial photographs that cover rather small areas, methods of image-based modelling were used to orthorectify the images. In this study, 9 vertical and 18 low oblique aerial photographs were processed as an ortho-mosaic, covering an area of 25 km(2), west of Wukro town in northern Ethiopia. Using 15 control points (derived from Google Earth), a Root Means Square Error of 28.5 m in X 35.4 m in Y were achieved. These values can be viewed as optimal, given the relatively low resolution and poor quality of the imagery, the lack of metadata, the geometric quality of the Google Earth imagery and the recording characteristics. Land use remained largely similar since 1936, with large parts of the land being used as cropland or extensive grazing areas. Most remarkable changes are the strong expansion of the settlements as well as land management improvements. In a larger effort, ortho-mosaics covering large parts of Ethiopia in 1935-1941 will be produced

Unmanned Aerial Vehicle (UAV) for monitoring soil erosion in Morocco

This article presents an environmental remote sensing application using a UAV that is specifically aimed at reducing the data gap between field scale and satellite scale in soil erosion monitoring in Morocco. A fixed-wing aircraft type Sirius I (MAVinci, Germany) equipped with a digital system camera (Panasonic) is employed. UAV surveys are conducted over different study sites with varying extents and flying heights in order to provide both very high resolution site-specific data and lower-resolution overviews, thus fully exploiting the large potential of the chosen UAV for multi-scale mapping purposes. Depending on the scale and area coverage, two different approaches for georeferencing are used, based on high-precision GCPs or the UAV’s log file with exterior orientation values respectively. The photogrammetric image processing enables the creation of Digital Terrain Models (DTMs) and ortho-image mosaics with very high resolution on a sub-decimetre level. The created data products were used for quantifying gully and badland erosion in 2D and 3D as well as for the analysis of the surrounding areas and landscape development for larger extents

Designing contested heritage within the sacred context. The AΧΕΙΡΟΠΟΙΗΤΟΣ monastery, Cyprus

The analysis of the Aχειροποίητος monastery shows the superimposition of different buildings: a domed church with a central plan, built in late Byzantine times over the ruins of an early Christian basilica, enlarged by the addition of three successive narthexes, and therefore transformed into a longitudinal basilica. The name Aχειροποίητος, literally “made without hands”, referred to a sacred icon hosted therein. A walled enclosure surrounds the church and contains the monastery, which developed in subsequent phases, with different additions, demolitions and restorations. We outlined the formation process of the complex, from the V cent. Basilica, to the transformation of the monastery into military barracks in the 1970s, as a premise for the restoration project. Recently the Department of Antiquities assigned the monastery to the Girne American University for its restoration and it is urgent to accomplish some statical interventions. The management of this site, hence the political situation of northern Cyprus, represents an interesting case study on the contested heritage issue. Nevertheless, the heritage management in Cyprus, for the complex political situation of the island, bears more difficulties than in other UE countries, but we should consider that every heritage site has someway a contested character. An architectural project was experimented, according to the typo-morphological approach of the Muratorian Italian School, based on the principle that new buildings should be the continuation of the old ones, without imitating them, but following their formation process, as the last step of an ongoing process. We did not conceive the new architecture as an object contrasting with the context, but following the full understanding of the processual transformations of the site, it was possible to design the new addition to the monastic building as a living organism, in conformity with the sacred context

3D mosaic documentation using close range photogrammetry

The paper describes the close range photogrammetric survey of a roman mosaic stored at Regional Archaeological Museum “Antonino Salinas” in Palermo (Italy). The aim of the work is the production of a full-scale representation (scale 1:1) of the mosaic useful for documentation and restoration processes. The research has allowed evaluating limit and potentiality of image-based approach using photogrammetric and computer vision (Structure for Motion) techniques in a context where the metric point of view is a very important factor

“Marmora” project: characterisation and provenance on historical marbles in the Apulia artistic and archaeological sites (Southern italy)

MARMORA is a research project designed by PugliaMia, Association for study, conservation and valorisation of Cultural Heritage of Apulia (southern Italy). The main topic of the project is the characterization and provenance of historical stone materials, in particular Roman marbles, employed and after reused in subsequent periods, in artistic, archaeological and architectural heritage of the region. The project aims to improve the scientific knowledge of these historical evidences and to guarantee their better conservation, valorisation and enjoyment. In cooperation with the Post Graduate School for Cultural Heritage and Landscape of the Polytechnic of Bari and with the Geoenvironmental and Earth Science Department of the University of Bari Aldo Moro, detailed studies about mosaics of St. Nicola’s Basilica and marble altars in the churches of the historical centre of Bari have already begun. The phases include 3-dimensional representation of artwork thanks to a photogrammetric acquisition, characterisation of materials, mainly in comparison with the most famous and complete catalogues of collections of ancient stones and marbles, and restoring and conservation suggestions. Preliminary results suggested the use and reuse of rare and meaningful marbles in the considered sites, highlighting their significant relationship with the local history. The adopted multi-disciplinary approach had proved to be a powerful way to study of marble artworks, which allowed to lay the groundwork for the future MARMORA focusses