Wednesday, December 03, 2014

Digital recording of and at Gebel el Silsila

One and a half year ago I was contacted by Maria who told me about Silsila and the projects that is running there. She asked me if I was interested in joining them and thereby bringing in the technology we are working with in the Humanities Laboratory at Lund University where I am working as a research engineer. This technology is focused on 3d data and we mainly apply it on archaeological research where we help to develop methods of using it in smart ways and incorporating it into the archaeological workflow. For that reason we are always interested in case studies, so Marias initial mail excited me. After a lot of planning, I and my colleague Giacomo Landeschi finally had the opportunity to visit the site and make a first study of it to find out if it is a site that would fit our line of research.

First fixed point established

The warmth that met us, not only temperature wise (having left a very cold Sweden behind us), but also from the very nice members of the team on site was a very good start. And I must say it only got better as the days passed. Gebel el Silsila is a really fascinating site and most of our techniques and methods could easily be used there. But for this first visit we decided only to bring a differential gps, since careful mapping of the site of course is a priority. During the week we managed to set up a number of fixed points to be used in the future either with the gps or a total station. We also mapped the perimeter of the main quarry and some other interesting details spread over some parts of the area. During the coming weeks we will post process the data and set up a basic 3d-GIS system that can be built on in the coming seasons.

Giacomo records a point at the top of the main quarry

We also work quite a lot with 3d-models in our lab and one technique for this that we used during the week is called structure from motion, in which a big amount of ordinary 2d photos is taken from a lot of different angels of an object and then processed in special software to create a 3d-model. You can see one such example here, where a 3d-model was made of a sphinx that is close to one of the quarries on the east side. It might take some time to load since it is rather big, even though its resolution is reduced quit a lot from the original 3d-model.
Since it is possible to move around the light source in most 3d visualizations systems, this technique also is good to apply to rock carvings or quarry marks. When the light hits the model of these from different angels, features in the carving can be more pronounced. One example of that is here (to move the light click on the light bulb to the left and then move the mouse over the model with the left mouse button pressed).

Photos been taken to make a 3d-model.

Silsila is definitely a site where we will like to do more work. We will be back next season and I already look forward to meeting Madame Silsila and also the wonderful team there again. I would like to thank Maria and John for their hospitality and generosity.

Stefan Lindgren