Orestis Kourakis
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Case study
Hypertitle number
1.12
Case study category
Artifacts

Rotonda of Thessaloniki

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Rotonda - aerial photograph
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The Rotonda, the only monument with a dome in Thessaloniki corresponding to the Pantheon in Rome, built during the Roman era, used in Byzantine and Ottoman times, belongs to the list of UNESCO World Heritage Sites. It is adorned with exquisite quality mosaics of the Early Christian period, the largest of which, the one in the zone known as “martyr’s frieze”, covers a total area of about 400m2.

Components
Objective
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The photographic documentation, in the most comprehensive way possible, of the dome’s mosaics of this unique monument in order to deepen the scientific research and also promote the monument to the general public.

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Rotonda - placing of the scaffolding into the monument

Challenges

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  • Height. The mosaic starts at 22m from the floor of the monument.
  • Size. The mosaic is 6 meters high and 65 meters in circumference.
  • Tiles’ material. There are countless gold and silver tiles in various orientations.
  • Curvature. The dome of the monument does not have an even curvature, as evidenced by a 3D scan.
  • Lighting. The monument has insufficient and fluctuating lighting throughout the day.
  • Terrain. The floor of the monument consists of ceramic slabs that can not support heavy lifting machines, such as large cranes.
  • Access. Large marble slabs at the entrance of the monument make the entrance of lifting machines prohibitive.
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Rotonda - view of the setup from top

Methodology

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  • The construction of a metal scaffolding in the center of the monument was chosen as the best option due to its very low weight, the large bearing surface and the high height of the camera placement.
  • The center of the monument as well as the exact placement of the camera was selected after a 3D scan of the monument’s interior and the use of a laser rangefinder, so that the optical center of the camera is equidistant from most points of the mosaic.
  • A variety of artificial light sources was used, which were adjusted one by one so that the whole mosaic was illuminated absolutely evenly, without being affected by natural light.
  • A panoramic robot  was used to photograph the monument in order to attempt to create a rollout of the entire mosaic into a single image.
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Rotonda - panoramic robot - Hasselblad

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  • The shots were taken with a medium format Hasselblad camera combined with a large telephoto lens so that the geometric distortion resulting from the irregular curvature of the monument would not significantly affect the final result. If the shots were taken with a wide-angle lens, as panoramic photographs are usually produced, it would not be possible to stitch all images photo-realistically. This was clearly noticed from the 3D scan as well.
  • At the same time, shooting with a telephoto lens inevitably led to an extremely large number of images that, exponentially increased the difficulty to process and stitch them, but gave us a gigantic final result (approximately 7000MP) that addresses virtually all documentation needs of the mosaic, from viewing the mosaic as a whole up to studying a minuscule detail of it. All this through the same single photograph.
Ultra-high resolution
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It is worth noting that I was not initially asked to produce a rollout for the whole mosaic, since the irregular curvature of the monument was taken into account, nor of course was a final 7000MP file requested. However, due to the highly significant archaeological importance of the monument, I considered it my duty to try to overcome the limits and possibilities of the rollout production and to create an image that not only has never been done before for this monument, but also promotes our knowledge and, at the same time, offers new potentials regarding the documentation of other similar monuments.

Rotonda - detail in high resolution
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Rotonda - view of the temporary exhibition - Ravenna

The Splendour of Mosaics

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In the temporary exhibition "The Splendour of Mosaics. Originals and Replicas from Thessaloniki and Ravenna", which took place inside the monument (2019-2020), the final images of this work were presented in large prints in the center of the space, in order for the visitor to enjoy the detail of these exceptional mosaics, as if standing next to them and juxtapose them in an equal relationship with the replicas of the mosaics of Ravenna.

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