Abstract
AbstractThis paper reviews photogrammetric error sources and their impacts on modeling and surveying for construction quantity takeoff, quality control, and site safety monitoring applications. These error sources include camera internal parameters (i.e., type, principal point, principal distance, and camera lens distortion coefficients), imaging settings (i.e., shooting distances, baselines, percentage of photo overlaps, number of overlapping photos, camera intersection angles, and angles of incidence), and processing software programs. To augment the body of knowledge on photogrammetric modeling errors, this paper further conducts experiment, which concerns characterization of the behavior of different strategies in selecting reference lines for fixing absolute scale of photogrammetric models. In construction photogrammetric surveying, it is imperative to convert the relative scale of a 3D model into absolute measurements so geometric measurements can be taken. Previous work suggests this can be done through the determination of a reference line in absolute units; however, the position and quantity of reference lines has not been investigated. This experiment attempts to tackle this issue. The result shows that one horizontal reference line in the middle of the object performed with consistent accuracy, but if a specific area on the object needs more accurate measurements, it is best to select a reference line in that area. The review and the experimental findings may help construction professionals better understand the performance of the photogrammetric surveying and apply it in their real-world projects.
Highlights
Photogrammetry, called image-based reconstruction or image-based modeling, is an old but powerful technology in many engineering applications
This paper provides a comprehensive review of state of practice in construction quantity takeoff, quality control, and site safety monitoring, and recent research efforts on evaluating photogrammetric error sources and their impact on modeling for construction surveying related applications
The surveying results were compared with ground truth data, which allows for accuracy determination and aids in determining the best strategy in selecting reference lines for scale fixing
Summary
Photogrammetry, called image-based reconstruction or image-based modeling, is an old but powerful technology in many engineering applications. The use of photogrammetry for reconstructing large-scale infrastructure scenes has motivated a flurry of research in testing the accuracy of camera network geometry for field measurement (Wackrow and Chandler 2008; 2011; Dai and Lu 2008; 2010; 2013; Dai et al 2013). Ground control points (GCPs), which are identifiable object with a known size, are selected so that the scale of the model can be set in real world units This method is limited when the terrain is mountainous and covered with foliage and trees and if there is a lack of clear existing usable targets. The sample distances for each object were collected by a total station or a tape measure and were compared to the distance values given by the iWitness models produced by the six scale bar scenarios.
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