The situla restored digitally

27 Nov

One of the outstanding silver objects from the Regolini-Galassi tomb  is a situla, a ritual bucket to contain holy water or milk.  The situla is only preserved partially and consisted of a wooden cilindrical bucket decorated with a silver cover showing three animals and palmettes, as the symbol of life.

Silver situla

Silver and wood situla of the Regolini-Galassi tomb (photo: Vatican Museums)

The silver decoration was found by the excavators in a fragmented state and recovered only partially.  Presumably, the situla was suspended in the triangular window opening (see image below) and when the situla fell down, it broke and many fragments that fell on the ground were destroyed by corrosion.

situla suspended in triangular window

Situla suspended in the triangular window of the tomb (image: CNR-ITABC)

We digitised the situla by turntable photography (so that the cylinder could be unwrapped as one image) and closeup photography, so that the hinge and the chain could be modelled in 3D by hand.  The main goal of unwrapping the cylindrical silver sheet was to digitally restore it.  The physical restoration has not been documented and dates back probably to the 19th century.

photographing the situla

Photographing the situla on a turntable at the Museo Etrusco Gregoriano (photo: CNR-ITABC)

The resulting photographs were assembled into one image, depicting the cylindrical surface of the situla.  As can be seen from the images below, the silver sheet has also been embossed and engraved.  The digital restoration focused on understanding the production process and improving the physical restoration, based upon that knowledge, as the parts that have been added do no contain any engraving or embossing.  It appeared also that a  few small parts of the original silver are missing (see for example the wing of the griffin below).

unwrapped decoration of situla

Unwrapped decoration of the situla (image: Visual Dimension bvba)

detail of situla decoration

Detail of the restored situla decoration, showing a griffin (image: Visual Dimension bvba)

The digital restoration was implemented through the creation of a displacement map, which is the most efficient technique to deal with embossed and engraved objects (see also our blog post on the digital restoration of a patera).  In Photoshop, we created extra layers on top of the unwrapped situla decoration image, one layer for the engraving, one layer for the embossing.  Additional layers have been introduced to simulate the deformation of the metal when engraving. We also created a transparency map to indicate the form of the cutouts in the silver sheet.

restored depth map

Digitally restored displacement map of the situla (by Visual Dimension bvba)

Study of the unwrapped image showed that the palmettes were made by hammering the shape with a tool in the form of the palmette.  This production process was simulated in Photoshop.  The resulting transparency and displacement maps are used in the interactive real time visualisation system that has been implemented by CNR-ITABC (see image below).

digitally restored situla

The digitally restored situla in the Regolini-Galassi tomb (image: CNR-ITABC)

This blog is part of the Etruscanning 3D project, that is being partially funded with support from the European Commission. This blog reflects the views only of the author, and the Commission cannot be held responsible for any use which may be made of the information contained therein.

 

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2 Responses to “The situla restored digitally”

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  1. The holmos and lebes digitally restored « Virtual reconstruction of Regolini-Galassi tomb - November 28, 2012

    […] map is created in the same way as for the other objects: we simulate the engraving and embossing process in different layers of a Photoshop image, that is […]

  2. Did griffins really exist? « Virtual reconstruction of Regolini-Galassi tomb - January 28, 2013

    […] of griffins, why are they depicted in this peculiar way? For example, a griffin is depicted on the situla which we have restored digitally (see image […]

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