As I have recently found out, the troubles in 3D visualisation of ancient buildings mostly come with the heights. It is relatively easy to find architectural plans, especially of very well known historical places such as Pompeii or Herculaneum. But what about heights? How high were those columns that now appear like little circles on a 2D drawing? Apparently, recording the heights was not a primary concern of those 18th century archaeologists and architects who had the privilege to see the Temple when it was still very well preserved.
Luckily, I have found the very precious Soane’s elevation and, even better, the rich Piranesi’s visualisations that I have chosen as my main reference to derive the heights.
I assumed that three drawings made by the same author and based on the same unit should have showed an high level of consistency. I was definitely over optimistic...
|Rear elevation and transection of the Temple of Isis in Pompei |
by F. Piranesi. Accessible at Bildindex
Piranesi included two scales in each of his Pompeian architectural drawings: Roman Palms and Piedes de Paris. For the purpose of my research, it was not really relevant which one I chose, as long as I was consistent with my choice. However, being Piedes the Paris a very tricky and slightly uncertain unit, I preferred to use Roman Palms.
The three drawings (the plan, the front elevation and the drawing showing on different levels the rear elevation and the lateral section) share the same unit system but the author applied different scales according to the dimensions of the sheet and the depicted subject.
In order to unify the dimensions and bring them all into a metric system, I had to “translate” them into an external known measure and rescale them proportionally. After that, I will only had to measure the heights of the elements in Piranesi’s drawings and build them in 3D Max (or so I thought...)
Even though the Pompeian Temple of Isis was probably built in Oscan foot, I decided to use he more established IRF (Imperial Roman Foot).
I started with the main plan. I have opened the jpeg file downloaded from the Bildindex in Adobe Illustrator and I have saved it in svg (the vectorial format). Then, using the pen tool I have re-drawn all the lines. Finally, I have exported the file in dwg (the autocad format) in order to import it in 3D Max.
The file was smoothly imported by 3D Max and the lines were potentially ready to be extruded. However, I prefer to use the imported lines only as a guide and keep an higher control on the model.
Even though Piranesi was an experienced architect, the digital plan of the Temple I produced should be considered only as a reliable approximation due to the many variables that can have affected its accuracy.
In the first place there are all the mentioned factors that can easily interfere with the material process of drawing (and that make almost impossible to find two identical records of the same place or building). Then, both the processes of engraving and printing could have added a level of information corruption.
Form the digital point of view, all the operations of scanning, compressing in jpg, uploading on the server, downloading from the server, converting in svg, exporting in dwg, importing in 3D max can potentially add a new level of data corruption.
Moreover, the biggest issue in the reliability of this information is probably my re-drawing of the plan in Illustrator. As almost all the ancient buildings (and many of the modern ones), the Temple of Isis is not made of perfect, straight lines. Developing only a simplified model as proof of concept for my dissertation, I decided to slightly modify the lines in order to obtain a more geometrically regular plan.