3D Documentation with TLS of Caliphal Gate (Ceuta, Spain)

Abstract

Three-dimensional surveying with a terrestrial laser scanner (TLS) has implied a revolution in the field of 3D modeling, as this methodology provides detailed point-clouds with simplified processes of capture. In addition to the point-clouds, other outputs can be obtained, such as ortho-images, virtual itineraries, 2D cartography, and meshes, which implies a second avenue of multimedia products, such as 3D Portable Document Format (PDF) files and interactive applications. All these options are interesting for the management and broadcast of cultural heritage. The works that have been developed in this research are aimed at setting a workflow for the TLS surveying works and subsequent data management for the generation of a 3D model of the Caliphal Gate of Ceuta, which is considered as one of the most important medieval findings in Spain in recent years, and its immediate surroundings. This model and the different outputs that have been obtained from it allow for the continuation of the historiographic analysis of the complex, while documenting a partial stage in the development of the works of enhancement. In addition to this, these products are not only useful in terms of conservation studies or enhancement, as they are also suitable for the dissemination of the site. Special attention has been set on the paid suitable software for data management while generating the outputs, and for its application by the final users.

Progressive Dilution of Point Clouds Considering the Local Relief for Creation and Storage of Digital Twins of Cultural Heritage

“…The E 3 variable is calculated separately for each point within the cloud. E 3 calculated for a point is defined as the variance of the distances of surrounding points (within a sphere with radius R) from the plane interspersed through them; it can be acquired, for example, as the third eigenvalue of the matrix according to Equation (1).…”

“…Nowadays, remote sensing techniques, such as 3D scanning (e.g., [1,2]), structure from motion (SFM) photogrammetry [3,4], or UAV lidar [5]) constitute common approaches for georeferencing and capture of historical objects. These methods produce huge amounts of data that can, among other uses, assist the documentation and preservation of cultural heritage objects for future generations [6,7] and/or the sharing of digital data on these objects among researchers or even with the public.…”

“…Algorithms performing uniform dilution are typical representatives of such approach, working, e.g., through random sampling (random selection of a user-defined number of points), octree sampling (the cloud point space is divided into voxels with user-defined size and one point-usually the closest one to the center of the voxel-is left in the cloud), or, the most widely used, space sampling method (points are excluded from the cloud on the basis of a user-defined minimal distance). These methods are very simple, fast, and implemented in the available software, e.g., in the CloudCompare software; thus, they are typically used as one of the first steps of point cloud processing ( [1,8]).…”

A Review of Tree Species Classification Based on Airborne LiDAR Data and Applied Classifiers

“…1. Terrestrial level (Terrestrial Laser Scanning, TLS) for, among others, architectural heritage [17,18], buildings [19][20][21], roads [22], and bridges [23,24]; or 2. airborne level (Airborne Laser Scanning, ALS), using a flying platform (aircraft, helicopter, or Unmanned Aerial Vehicle; UAV), for aerial objects such as forests [25][26][27] or urban environments [28,29].…”

Advances in the Restoration of Buildings with LIDAR Technology and 3D Reconstruction: Forged and Vaults of the Refectory of Santo Domingo de Orihuela (16th Century)

“…The assessment of intervention needs in historical and heritage buildings requires information and knowledge offered by the application of precise techniques for their registration, which is why it is common practice in the preliminary phase of data collection in architectural restoration projects. Terrestrial laser scanner (TLS) [1,2] and photogrammetry [3][4][5][6][7] are often used as they are techniques that allow the necessary graphic documentation to be obtained with great precision if used appropriately [8][9][10]. Each building requires individualised treatment, so that, although the methodology is general, its specific application in each case requires adaptation to the particular conditions of the architectural element.…”