3D Printing Historic Buildings

On my last visit to Athens a couple years ago the opportunity arose to have a good, close look again at the Choragic Monument of Lysicrates. As my students will know this is a fourth century BC classical Greek monument famous both for its very early use of a Corinthian order and its frieze of sculptures depicting episodes from the myth of Dionysus. It was carefully surveyed by the British architects James “Athenian” Stuart and Nicholas Revett as long ago as 1751 and they published the first measured drawings of it in their ‘Antiquities of Athens’, in London in 1762. Getting good measurements of the extant remains of ancient buildings is half the battle in representing them, accuracy and attention to detail is everything, and Stuart and Revett’s drawings are still widely regarded as being the authoritative documents on the monument as it was in the 1750’s. This is important because time, human interference, air pollution and erosion have taken their toll on this structure, erasing significant parts of the detail and it is clear that Stuart and Revett saw and were able to measure and draw aspects of the monument which are no longer there. It occurred to me that it would be useful to be able to re-build a copy of the Choragic Monument based on their measured drawings and photographs of the monument as it is today, so that the design might be fully appreciated as it was intended to be, or at least Stuart and Revett’s interpretation of it. Clearly this would be hugely expensive and very time consuming and is not in fact a new idea. After the publication of the ‘Antiquities of Athens’ various copies and derivations of it were built around the world but none conform entirely to the Stuart and Revett survey and some depart from it very considerably. For some time myself and colleagues at De Montfort University  had been developing techniques for 3D printing large scale, architectural models directly from digital ones which until then had only ever existed in a computer. Being able to fly around and go inside a reconstructed building on a computer screen is all very well but there is nothing quite like the physical tangibility of a real object. 3D printing allows you to produce real objects from digital ones and so gives this tangible reality. The basic principles of the process are quite straight-forward, the computer takes the digital model of the building and cuts it into very, very thin horizontal slices, a bit like a salami. These digital slices are then sent to a special 3D printing machine which then ‘prints’ each of these thin slices. De Montfort University has a number of different 3D printing machines which use different materials for this bit, you can print in plastic, in gypsum plaster, in tough resin and even in laser fused stainless steel or titanium (these last two are admittedly pretty expensive). But all of them use the same basic layering technique, printing layer after layer, a bit like a photocopier printing a slightly different image onto each piece of paper. De Montfort University also has a machine that does actually use paper for 3D printing! We decided to produce a highly accurate digital model of the Choragic Monument of Lysicrates and 3D print it in bonded gypsum powder which is relatively inexpensive in terms of 3D printing (gypsum is used to make plasterboard and plaster-mouldings). Modelling complex geometries like those of this historic monument is a highly skilled task requiring years of training and experience, but this was just the first step. We also wanted to make the model much larger than could be built in one piece by the machine so it was re-engineered to be built in four separate pieces, which would then be assembled into the finished model. Finally we developed a unique post production treatment technique which not only rapidly hardened the relatively soft gypsum once it was printed but also gave it a permanently bright white lustrous finish that sparkles in the sunlight, a little like the Pentelic marble that the original monument is made from. In November 2010, the finished 2 ft high model was completed and was selected for exhibition as one of the centerpieces of the Royal Scottish Academy’s Open Exhibition in their gallery in Edinburgh and was on display until just before Christmas that year. As a demonstration of how digital technologies can assist in representing historic buildings like the Choragic Monument of Lysicrates and promoting public understanding of them this particular model has been a great success and we have since printed another identical one to show how the process can be repeated to exhibition standards with complete confidence and accuracy. There remain exciting challenges in this creative field of research but it is clear that 3D printed reconstructions of historic buildings are a very effective way of representing both the buildings and the issues surrounding them to the public.

About Douglas Cawthorne

Reader in Digital Heritage at De Montfort University.
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