EXACT AND NATURAL SCIENCES

Scientists use a powerful laser scanning technology in an archaeological place

It was promoted by CONICET La Plata scientists and it’s the first one in the country. It will be used to have 3D reproductions of one Inca center.


LIDAR technology use in the area. Photo: Luis Enrique Pinto

As it happens with some feats, this one also began as almost a utopia. Reinaldo Moralejo, CONICET assistant researcher at the Museo de La Plata, read about one sophisticated and expensive tridimensional scanning conducted from a plane on a central America archeological site and dreamt about being able to do the same in his field of study. He carried out some research and made the arrangements. So, in less than one year after that first idea, the scientists managed to carry out a similar process in the Inca location “El Shincal de Quimivil” thanks to a Collaboration Agreement between the Universidad Nacional de La Plata (UNLP), the Universidad Nacional de Catamarca (UNCa), the Secretaría de Estado de Cultura of that province and Consular Consultores Argentinos S.A. company.

This new technology is called LIDIAR (Light Detection and Ranging) and is the emission of thousands of laser rays per second to obtain a high quality 3D digital model of the surveyed land. It is used for research that implies the knowledge of one geographical area, like in geology, geophysics and geodesy, and also for the construction of big civil works: ports, bridges or routes. This is the first time this technology is used in our country. It is worth mentioning that El Shincal was a political, administrative and ceremonial center built and inhabited by the Inca people between the end of the fifteenth century and beginning of the sixteenth, period in which the Argentine northeast was part of the Inca State. With a 30 thousand meters central square, people knew that this place was a significant religious and symbolic point in the region. It was discovered in 1901 and it’s located 5 kilometers away from the district of Londres in Catamarca.

The scanning in the place was carried out at the end of last November and, according to what was approved, the first results are going to be known in May 2017. “The surveyed information will allow us to undertake complex studies such as the detection of structures hidden by the vegetation and modeling of the topography of the places to counter the effect of the harmful chemicals”, Moralejo, one of the responsible participants of the agreement, states. The other one is Daniel Del Cogliano, CONICET principal professional at the Facultad de Ciencias Astronómicas y Geofísicas of the UNLP, who has worked for seven years with this laser technique that is very common in this discipline.

“Reinaldo talked about his idea so we began to make the arrangements with the only company that provides this technology from a plane; a very expensive service for our financing capacity”, the expert recalls. After the initial enthusiasm, the economic issue became the main obstacle. “For that reason, I thought about the possibility of having an interinstitutional agreement in which all parts could contribute without involving money. As the company was interested in the contact with academic institutions and the collaboration with the project,  the flight, the processing and interpretation of data were free”, the scientist comments. Del Cogliano and his research team participated by providing the second LIDIAR device, in this case a terrestrial one. The instrument, which belongs to the UNLP and is operated through a tripod, used the same technology for some structures of El Shincal to complement itself with the air survey.

For different issues linked to archeological purposes and relevant heritage, the researchers chose four structures for the terrestrial scanning. “At first, we have selected more, but then we established one order of priority as the laser scanning of each takes almost one day”, Moralejo comments. So the elements analyzed were the ceremonial platform of the central square, known as ushnu; two residential structures called kanchas; and one access staircase. When we finish processing the information, we are going to have detailed and pinpoint accurate 3D reconstructions that will allow experts to store them virtually and detect any future alteration or destruction.

LIDAR and air photography survey was conducted in three hours on three thousand hectares, including El Shincal and other adjacent areas: Paraje La Aguada and los Tambillos de Zapata. “We seized the chance and explored places that have not been studied. The results are going to allow us to see if there are ancient remains under the thick vegetation, avoiding blind exploration”, Moralejo explains and adds: “We will also be able to detect the remains of roads, agricultural terraces, storage facilities, residential and ceremonial structures, and aqueducts, among others.” Experts agree on the fact that the objectives of this project go beyond archeological studies and reach heritage and conservation issues. As regards this, the researcher comments that “there are different parts of the site affected by gully erosion, which are landforms almost ten meters deep produced by rains. Now it will be possible to conduct detailed study on the hydraulic system so as to know where the water leaks and provide solutions.”

Both LIDAR procedures were supported by the action of six GPS devices provided by both institutions. “In the future, in order to integrate information obtained from the air and the earth, we have to place it in the same reference system; so for this reason we use satellite navigation to support this study”, Del Cogliano explains and adds: “There is a lot of dense and accurate information that has to be “written in the same language” so as to make it compatible.”

After the three days and a half’ experience of working in the archeological site, the scientists emphasize the role of the villagers who were previously informed about the project and the activities that are going to be done there. “For us, joint work is the only way of making this possible. El Shincal is the only ceremonial center the locals link to their own ancestors and feel it as part of their own”, Del Cogliano comments. He also agrees with Moralejo in the fact that “if the community is informed about the studies we are conducting, they can participate and accompany in different issues, even when we need to solve any problem during the studies.” The experts also highlight how intense and successful have been the tasks performed by all parts as a team.”

By Mercedes Benialgo
About the research:
Reinaldo Andrés Moralejo. Assistant researcher. División Arqueología, Museo de La Plata, FCNyM, UNLP.
Daniel Héctor Del Cogliano. Principal professional. FCAG. Professor at UNLP.
*Other participants in the study: Martín Lucas Rodríguez and Paula Espósito, Dirección Provincial de Antropología dependiente of the Secretaría de Estado de Cultura de Catamarca; Fabián Casas and Leandro Pinto, of Consular Consultores Argentinos S.A.; Mirtha Rodríguez Zar and her team at the Facultad de Tecnología y Ciencias Aplicadas (UNCa); Lautaro Simontacchi of the Facultad de Ciencias Astronómicas y Geofísicas (UNLP); Víctor Mezio of the Facultad de Bellas Artes (UNLP); and Daniel Munz and Diego Gobbo of the Facultad de Ciencias Naturales y Museo ( UNLP).