Measurement of transparent plastic sculptures using photogrammetry, laser scanning and touch probing for conservation purposes

Tate is currently undertaking a multi-disciplinary research project to document plastic sculptures by Naum Gabo (1890-1977). Gabo experimented with cellulose nitrate and cellulose acetate, materials which interestingly for photogrammetrists constitute early photographic film base materials upon which a significant body of measurement and analysis research is based. Some of these early plastics are now showing typical signs of deterioration even though they are stored in stable environmental conditions. Faced with the gradual loss of a substantial part of an important collection, UCL and PCA were invited to undertake a study of available measurement technologies that could be used to accurately document the sculptures. This paper reports on the advantages and disadvantages found with each technique supported by quantitative comparison data. An image of 'Spiral Theme', one of the sculptures included in the study can be seen in Figure 1.