Before replicating missing parts on still preserved figures or even reconstructing historical models, an intensive analysis of the stock and all available sources was necessary.
Important indications are the still intact evangelist figures, which were consequently measured, new photographed and partly also scanned. In addition, historical photo material from the archives of the Bavarian State Office for the Preservation of Historical Monuments and the Philipps University of Marburg was assorted and evaluated.
The assorted 3D data of the original parts were a source of immeasurable value for a multitude of analyses, which could be carried out comfortably at the 3D lab of DIT. So it was possible to display any kind of views, cross sections, benchmarks and certain details of the digitalized parts of the figures. The latest scientific and technical methods thus provided the basis for developing the supplements as faithfully as possible.
Furthermore there was the possibility to create animations using 3D software, which gave insights as they could never have been observed at the original object. For example, camera settings could be virtually simulated or different hand positions could be varied without having to move actual masses.
In addition to the studies in the virtual space, hand-drawn anatomical sketches helped to understand how the figure was spatially constructed. As there were no historical photographs of St. Luke from the side, the reconstruction of depth information was a particular challenge.
Since the original sculpture with a height of about three meters was very large, it was necessary to first carry out plastic studies on a smaller scale. Ever since, sculptors have in this way made small so-called "Bozzetti", after which the great figures were created. This method was therefore also a useful approach for the Theatine-Project.
No matter which combination of techniques is used, sculpting must always be included. Whether forming clay or plasticine, working on wood or adjusting points in virtual space, the result is always a three-dimensional form. Thereby, the main advantage of 3D modelling is that virtual objects can be rotated, edited and scaled in the view relatively easy.
However, it is also advantageous to use the traditional method of working with real Bozzetti, as the 3-dimensionality is only simulated in a 2-dimensional view when working with a computer. However, a real model can be turned and touched in the hand, which allows a completely different experience when dealing with form.
Thus, the final model, the Bozzetto with all the supplements to Luke, consisted of a combination of different 3D printing parts and a hand-modeled area made of industrial clay. The basis was a laser-sintered model of the scanned torso of Luke made of white polyamide on the scale of 1:7. It was supplemented by other printed elements from 3D modelling, such as the hands. The great defects in the area of the garment were finally reproduced by hand after using the historical photographs.
Before the hand-modeled forms could be further processed in 3D, they had to be digitized. While structured light scanners and various hand-held 3D scanners have been used to digitize the original remains of Luke in the church, another method should be used for the very delicate bozzetto.
The Deggendorf Institute of Technology has an X-ray tomography measuring instrument, which is primarily used for material testing and other highly accurate measurements. It should also be very useful in the Theatine-Project. With about 50 centimeters height, the Bozzetto of Luke had been designed in such a way that it could be measured in this device just yet.
During digitization in the tomograph, 3D data were generated, which were not only extremely accurate, but could also precisely capture all undercuts, which would not have been possible with other 3D scanning methods. The hand-modeled supplements for St. Luke developed on the small model, afterwards existed as 3D data and could be further processed and refined on the computer in virtual space.
For this purpose, the data was scaled back to original size and subtracted from the primary scan of the torso of Luke. In this way, fitting supplements were created which, like puzzle pieces, perfectly matched the jagged charcoal surfaces on the original. Still, the fragments, which had been manually modeled on a small scale, were not precise enough, however, and were each reworked and refined in 3D modelling.
Anatomical drawing on historical photograph
Drawing: Krisztina Sárközi
The Bozzetto with modeled supplements
Photograph: Deggendorf Institute of Technology
Virtual modelling at the digitized bozzetto
Graphic: Deggendorf Institute of Technology
© 2017 Deggendorf Institute of Technology
© 2017 Deggendorf Institute of Technology