3D Modeling and Section Properties of Ancient Irregular Timber Structures by Means of Digital Photogrammetry

Abstract

This article deals with the application of low‐cost Close Range Digital Photogrammetry to obtain an accurate three‐dimensional (3D) re‐construction of irregular geometry structures in the field of building construction, with special attention to the evaluation of old structures. Photogrammetry can be used as a non‐destructive tool to give precise 3D information about the size and shape of some elements of a structure, quickly and with no risk to the surveyors. The geometric data achieved can be used by engineers and architects to obtain the section properties, and also to estimate the influence of geometric variations in the distribution of stress. This allows us to compare areas subject to higher stress, and could be of special interest regarding some historic and cultural heritage constructions—such as the timber roof structure included as a case study in this work—from two points of view: On the one hand, Photogrammetry makes it possible to obtain precise 3D models of highly irregular elements, as old timber purlines and trusses in the case of ancient constructions; on the other, Photogrammetry is a non‐contact method that minimizes the measurement time and allows us to obtain the section properties, which can be used together with some material testing characterization to evaluate the structural safety of the construction.

3D Reconstructions Using Unstabilized Video Footage from an Unmanned Aerial Vehicle

“…Combining the reconstruction data with the original 2D image data generates a detailed 3D record of the surfaces of a structure. Such a record is useful for conservation and restoration work [28].…”

Techniques of massive data capture: A comparative approach for the assessment of complex spaces in architectural heritage

“…The typical parameters that are used for capturing images were taken into account (Pedro Arias, Carlos Caamaño, Lorenzo, & Armesto, 2007). However, the changing light conditions and the different exposures of the surfaces required image preprocessing and texture equalization.…”

A Photogrammetric and Computer Vision-Based Approach for Automated 3D Architectural Modeling and Its Typological Analysis

“…Second, once the relative angular and spatial position of the images is solved, we carry out a comprehensive bundle adjustment by means of an iterative and least-squares process based on the collinearity condition [5] and by adding the object coordinates to allow a full georeferencing of the images (Equation (5)). These object coordinates are incorporated into the orientation process thanks to the targets spread about the scene or by means of natural points, whose coordinates are measured by expeditious topographic survey (i.e., tape measure, manual measurement devices).…”

“…It even allows any type of camera, calibrated or uncalibrated [3], smartphone or tablet [4]. Photogrammetry has even a third advantage: its commitment to the accuracy and reliability of the results [5]. This means that, for many uses, photogrammetry stands out as a serious competitor against the low-cost laser systems.…”

“…However, the integration of algorithms and techniques from computer vision has enabled such obstacles and dependence to be overcome and automatically solved during the 3D model calculation process (structure from motion (SfM)) [10,11]. More specifically, the main advances concern multiple image matching strategies based on FBM (feature-based matching) and ABM (area-based matching), which allow one to obtain, by means of collinearity equations [5], the spatial and angular position of the image, as well as a preliminary dispersed geometry of the scene in an arbitrary and local system of coordinates [12]. Once the image resections are solved, the direct process may begin multiple direct intersections; this process also sustained on the concept of collinearity, which leads to the reconstruction of the 3D model or a dimensional-metric analysis of the object or scene.…”