3DVisA Index of 3D Projects: Art History - Paintings
The Westminster Retable Conservation Project
This project has produced a 3D surface model of Westminster Retable (Westminster Abbey, London) using photogrammetric data. The photogrammetric survey was undertaken primarily to assess mechanical changes to the structure caused over the years by environmental factors. "However, as a result of these surveys, a 3D model of the Retable was created that offered other functionalities. Most importantly, these additional functions have allowed accurate measurements to be made without direct physical contact with the Retable itself."
The Westminster Retable depicts the miracles and other events in the life of Christ. It was produced in the late thirteenth century under the patronage of Henry III or Edward I. The oldest surviving easel painting in Britain, it is regarded as the most important Gothic panel painting. It was produced by Anglo-French artists possibly as the high altarpiece for the Westminster Abbey. After the Dissolution of the Abbey it was reused as part of a cupboard and was only rediscovered, much damaged, in 1725. It is 3.4m long, 1m high and about 0.1m thick and consists of an oak support which carries numerous decorative and structural features and materials including: wood carvings, paintings, glass, dowels, metal, stone and vellum. During the restoration process it was necessary to conduct environmental response monitoring and mechanical deformation checking to ensure the integrity of the Retable. A multi-image digital photogrammetric system was chosen for this purpose since it offers a periodic method of non-contact recording. However, the image record and its associated spatial data can be used for other purposes including providing the basis of a visual database used to manage the conservation process and to automatically generate a three-dimensional surface model. The model allows the art conservator to make measurements and comparisons between different parts of the structure.
A photogrammetric system was used for high precision monitoring during the conservation process using multi-photo network adjustments, camera calibration and stochastic deformation analysis techniques. This technique was able to monitor discrete points on the surface of the Retable to a precision of 20 micrometers. Techniques have been developed to allow the automatic generation of an accurate surface model from the multi-photo image record. This latter work drew upon an integration of point interest algorithms, multi-photo image matching, epipolar geometry, extracted lines and edges to automatically generate a dense point cloud and triangulated surface model. These methods were integrated within an error propagation model to ensure the precision and reliability of the extracted data.
Project dates: Completed April 2005
Funding: The Heritage Lottery Fund, UK and the Getty Grant programme.
Resource status: The model has been integrated into the art conservation database system with the aim of allowing conservators to make dimensional and shape comparisons between some 3000 different structural elements on the Retable.
Contributors: Stuart Robson and Helen Papadaki, Department of Geomatic Engineering, University College London, UK; Spike Bucklow, Hamilton Kerr Institute, University of Cambridge, UK; Neil Woodhouse, Leica Geosystems GIS & Mapping, San Diego, CA, US.
Sources and further details: Robson, S., Bucklow, S., Woodhouse, N. and Papadaki, H. (2004), Periodic Photogrammetric Monitoring and Surface Reconstruction of a Historical Wood Panel Painting for Restoration Purposes, Proceedings of the ISPRS Confeence, Istambul (pdf); Westminster Retable, exh. cat., National Gallery London, 2005.
Record compiled by Anna Bentkowska-Kafel from material supplied by Stuart Robson. Last updated: 11 September 2006.
3DVisA gratefully acknowledges the help of Stuart Robson with preparation of this record.
© Westminster Retable Conservation Project and 3DVisA, 2006.
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