Alternatives for the three-dimensional reconstruction of patrimonial zones based on photogrammetry and LIDAR scanner. The Barranco of the city of Cuenca as a case study

Abstract

The emerging need for up-to-date information, coupled with the lack of adequate documentation of historical city sectors, as well as the accelerated technological development of the time, has led to the creation of several tools for surveying geographic, topographic and archaeological information that may contribute to the study of urban-morphological transformations and to the documentation and protection of built heritage. With this background, the study aimed to validate a methodology for the identification and analysis of built heritage alterations. A detailed survey was carried out using aerial and terrestrial photogrammetry, based on the use of tools that generate two-dimensional data such as Drone DJI Phantom 4, Nikon D5300 camera, GoPro Hero 3 Black Edition camera, and an Iphone 7 Smartphone. In the same way, this study was complemented with a three-dimensional method, based on a LIDAR laser scanner. The data was obtained based on orthogonal drone flights, which were complemented by partial documentation of facades of some of the buildings in El Barranco de Cuenca, Ecuador, obtained through the before mentioned two and three-dimensional tools. This process was carried out twice, with an interval of 4 months, to identify changes. When completing the data processing, two cases were found where the buildings were altered in different magnitude. In addition, the research served to establish the most versatile instruments for the three-dimensional reconstruction of point clouds in the historical city of Cuenca. In this sense, the LIDAR technique is the tool that provided the best results, however, the survey took more time and was more expensive; on the other hand, considering the quality-price ratio, the DJI Phantom 4 drone turned out to be the most recommended device for this type of studies.