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The brick vaults of the Alfonsina Tower in Lorca Castle. Geometric aspects and possible sources
Published in João Mascarenhas-Mateus, Ana Paula Pires, Manuel Marques Caiado, Ivo Veiga, History of Construction Cultures, 2021
P. Natividad-Vivó, R. García-Baño, M. Salcedo-Galera, J. Calvo-López
We took photographs in JPG format covering the entire intrados surface of the vaults. A Canon EOS 550D camera was used for the vaults of the first and second floors and a Nikon D5000 for the vaults of the third. In all cases, we provided a minimum overlap between images of 60%. After, we processed the photographs using Agisoft Metashape, an automated photogrammetry software. The workflow with this software was developed in the following two phases. Firstly, the photographs were aligned by detecting the tie points and estimating the camera locations, and then the dense point clouds were generated with millions of coloured points that precisely define the shape of the intrados surface of the vaults. Finally, the point clouds were exported in E57 format and loaded in Rhinoceros 3D, a three-dimensional modelling software. The final plans were drawn with this software. In particular, the point clouds were processed using a script programmed in Python by P. Natividad Vivó and were projected orthogonally to create the orthophotos with textures of the materials that we can see in the final plans.
Force-System Resultants and Equilibrium
Published in Richard C. Dorf, The Engineering Handbook, 2018
The term photogrammetry refers to the measurement of photographs and images for determining the size, shape, position, and other spatial attributes of features appearing in the images. The most common application of this technique is aerial photogrammetry, in which nominally vertical photographs are used to produce topographic maps, which are often used for engineering design and land development. Aerial cameras are made to precise tolerances; small systematic errors that may be present in such photographs can be modeled mathematically so that accurate ground positions and elevations can be inferred from measurements based on these photographs. The mathematical basis of the imaging equations that relate object points (three dimensional) to image points (two dimensional) is that of a perspective projection, with a point (actually two points) in the lens assembly serving as the perspective center (s). The geometric relationship between the image and object spaces may be modeled in analog fashion by optical rays or by mechanically gimbaled steel rods. Today it is more commonly modeled mathematically in an analytical instrument.
Enablers dictionary
Published in Adriana X. Sanchez, Keith D. Hampson, Simon Vaux, Delivering Value with BIM, 2016
Adriana X. Sanchez, Will Joske
Photogrammetry commonly refers to the process of using images and photographs taken from different points of view to automatically or semi-automatically generate a 3D object or model. The process generates a point cloud similar to that from 3D laser scanning with the advantage of it being enriched with colour data for each point and often also being less costly and more flexible than laser scanning (Hichri et al., 2013a; BIMe, 2014; Tuttas et al., 2014). However, this term has also been used to describe the process of including photographs of system components into the model (Thomas et al., 2004). Commercial tools such as Autodesk’s BIM360 Field include this functionality so photographs can be taken on the field and directly uploaded to the system for reporting or record-keeping purposes (Autodesk, 2015f). Also from Autodesk, 123D Catch is an app that allows the user to create 3D images and basic 3D models using regular smart mobile devices (Autodesk, 2015l). Trimble has a 3D handheld scanner device specially designed for this purpose which includes a high-resolution camera and android tablet (Trimble, 2015b).
Experimental and Theoretical Studies to Characterize Structural Behavior of Dry-Stone Corbelled Arches under Support Disturbances
Published in International Journal of Architectural Heritage, 2022
Photogrammetry is the science of measurement from photographs. When light rays hit an object, they reflect, pass through the camera lens, and get captured in the camera’s image sensor or film. The position of a point in 3D space can be computed once the point is imaged on each photograph, with known parameters of the camera (i.e., focal length, lens distortion, etc.) from camera calibration, and relative positions and angles of the camera when the photographs were captured. The main factors affecting the accuracy of the measurement are photo resolution, camera calibration, point angles, photo orientation quality, photo redundancy, targets/marking precision. The process of camera calibration is to evaluate the camera internal specifications such as camera focal length, format size, principal point and lens distortion more accurately as sometimes the EXIF data from the image may not contain all the required information about the camera, say, as an example size of the image chip may be missing, or the data such as focal length provided by the manufacturer may be approximate.
Radiation imaging using a compact Compton camera mounted on a crawler robot inside reactor buildings of Fukushima Daiichi Nuclear Power Station
Published in Journal of Nuclear Science and Technology, 2019
Yuki Sato, Yuta Terasaka, Wataru Utsugi, Hiroyuki Kikuchi, Hideo Kiyooka, Tatsuo Torii
In addition to the LRF, photogrammetry can be used to acquire a 3-D structural model of the working environment. Photogrammetry involves reconstruction of the 3-D models of objects or scenes by combining photographs taken from multiple angles. Moreover, we have developed a method to three-dimensionally grasp the location of radioactive substances by superimposing images of radioactive substances on a 3-D structural model of the work environment reconstructed using photogrammetry [6]. Haefner and Vetter et al. [7,8] reported a method involving superposition of an image of radioactive substances measured using a gamma-ray imager on a 3-D model of the measurement area prepared using Microsoft Kinect or other LRFs to visualize radiation sources on a 3-D real space image. The Microsoft Kinect sensor outputs RGB images and 3-D point cloud data of the scenes.
HBIM Application in Historic Timber Structures: A Systematic Review
Published in International Journal of Architectural Heritage, 2023
David Santos, Hélder S. Sousa, Manuel Cabaleiro, Jorge M. Branco
Photogrammetry is a technique from which it can be obtained accurate measurements and 3D geometric information using photographs. It is based on a triangulation method (Beraldin 2004; López et al. 2018) and orthographic images, point of clouds and even surfaces with texture can be acquired from it (Andrews, Bedford, and Bryan 2013; Arias et al. 2007). Photogrammetry proves to be a suitable method to determinate the irregular cross-section geometry in timber structures, allowing to obtain accurate 3D models of these structures, with a considerable low cost (Armesto et al. 2009).