Geophysical methods have made it possible to explore the site in detail and more exactly define the geometry of the structures and their geological surroundings. In this context, geophysical surveying has centred on two fields in the western section and, especially, on the field in the eastern sector, as they allow extensive work that is impossible in the wooded areas.
The main techniques used are magnetic surveying, which provides information on areas with alterations in the electromagnetic field like the ones produced by combustion, ground-penetrating radar, which provides a more precise description of built structures, and electrical surveying, which documents variations in the potentials of sediments.
The results and interpretations obtained with the different techniques are used in the planning and management of subsequent excavations.
Image: © Orthophotograph property of the Institut Cartogràfic i Geològic de Catalunya, accessible on www.icgc.cat.
Map of the magnetic gradient of sections 1 (west) and 2 (east)
The blue and red colouring indicates areas with temperature alterations or containing metals. The black linear elements could indicate built structures. The white elements could indicate accumulations of sediments or structures dug into the ground, like silos.
Map of reflected energy
Represented are depths included between 0.55 and 0.65 metres below ground. The built structures and the surface bedrock are in black.
Map of electrical conductivity
Obtained from electromagnetic surveying by the ORBIT group at Ghent University (Belgium). In black, the elements of marl and limestone: rock base and building material of the site. In white, clay marls from higher levels.
In view of the multidisciplinary nature of the Puig Ciutat archaeological project, it was necessary to develop a common platform from which to visualise and interpret the data obtained. In this respect, the platform used was built using the Qgis free software program. Alongside this, the Sig.Arq. program was used to manage the results of the excavations. This program allows you to enter the results of excavations in a spatial data base in a way that is systematic, uniform and georeferenced.
Image: Orthophotograph property of the Institut Cartogràfic i Geològic de Catalunya, accessible on www.icgc.cat.
To analyse and document the best-preserved structures in the Puig Ciutat site in detail, several photogrammetric studies have been performed. This technique provides geometric, radiometric and semantic information about three-dimensional objects in reality, using different photographs taken from different points of view. The model generated, despite not having real measurements, does have relative measurements that can be converted to real measurements and even to geolocation points if backup markers on the ground are used. This technique produces a model of reality, first in the form of points and polygons and, subsequently, on a solid, textured surface. In this respect, photogrammetry not only provides volumes and 3D measurements, it also offers quality, accuracy and speed in the execution and obtention of large amounts of information.
Point clouds generated with the Agisoft Photoscan program
Here we see the angle and position of the photographs taken in one of the archaeological sectors excavated at Puig Ciutat
Low density point cloud
Points located in space obtained by triangulation based on overlapping images with different viewpoints
Point cloud with colour information
Colour taken from the photographs and applied to the points in space
Layered triangle mesh without texture
Triangle mesh generated by joining the points in the cloud.
3D mesh with texture
Texture generated from photographs taken in the field
The process of restoring archaeological movable objects begins the moment they are discovered, as the state in which they are found in the subsoil is altered. The aim of acting on archaeological material is to recover the objects’ lost solidity and stabilise all active factors of alteration.
To a large extent, restoring Puig Ciutat has been the work of Eulàlia Ribó and thanks to the availability of the Centre de Restauració de Béns Mobles de Catalunya (CRBMC, Catalan Restoration Centre for Movable Heritage).
Photographs by Ramon Maroto (CRBMC).
Black glazed ceramic vase from Cales for domestic use
Bronze hooks for domestic use
Tip of a wrought-iron catapult bolt
Black glazed pyx from Cales for domestic use
So as to document the most important and best-preserved items in 3D, a low-cost scanning system has been used which is known as the Matter and Form project. With this we can generate a 3-dimensional digital version of the main items in a short time. The main object of this operation is to aid in reporting and disseminating the different materials recovered during the different archaeological campaigns through a Virtual Museum.
Ceramic item in the 3D scanner
Noise reduction tool for point clouds generated with photogrammetry or with 3D scanning