(Dipartimento di Architettura, Disegno Storia Progetto, Firenze, Italy)

Keywords: Bab al-Difaf, Granada, SFM

Cadi? Los tableros? Bab al difaf? There are so many names for a single enigmatic monument along the fortifications of Granada.The city of Granada is full of monuments , witch  are known for their beauty all over the world , whose meaning and role within the urban city planning is well known and easily readable. There are some examples which have not found yet a specific location and a role within the “system” in the city and they are still waiting for a correct interpretation. In major part their “suspended” character part is caused by incompleteness of the State’s archival records, by degradation of the monument and also by missing oral testimony, which keeps alive its history and its location in the city.
What people know as “puente de Cadi,” is an example of the above mentioned conditions and this monument from Ziri period, placed between the Islamic district of the Albaicin and the Alhambra, raises still a lot of interests among the group of researches.
So how is it possible to study and analyze this “forgotten” monument? Our goal was to reach a 3D model which can be analyzed in detail. The main problem to resolve was the accessibility to the site because between the monument and the main street there the river Darro: the solution could be to use a laser scanner technology, but due to its excessive awkwardness, it was not possible. That’s was why we chose to work with the aid of software SFM (Structure from motion). This software uses photos and it is able to generate 3D models. To achieve a very accurate 3D model we had to take more than 4000 photographs and with the help of many software including Agisoft Photoscan, Inus Rapidform and Geomagic, we were able to achieve a mesh model with approximately 100 million of faces, then we shrinked the model aproximatly to 15,000,000 faces, ready to be handled by desktop computers.
The use of so accurate digital model allowed us, simultaneously with researches made in archives and by collaboration of researchers of LAAC of Granada, to reache a plausible virtual reconstruction of the door of Bab Al-Difaf that can be used for a development of further hypotheses of study.