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Displacement measurement of the soil nail walls is a very important task in monitoring tiny movements in excavations to prevent disastrous accidents like wall collapsing. In building construction projects, this is usually done by either micro-geodesy or accurate instrumentation methods. In this research, for the first time, the use of close range p...
Contexts in source publication
Context 1
... the pilot project two types of cameras were tested in order to ensure the indepen- dence of the results from the camera type. The first camera was a Canon PowerShot SX130 IS and the second one was Fujifilm Digital Camera FINEPIX HS20EXR9 (Table 2). Based on the results obtained from the pilot project, the Canon PowerShot camera was selected to use in soil nailing project. ...
Context 2
... quick method for monitoring the suspicious walls with unallow- able displacement is vital in construction projects. Accord- ing to this goal, the accuracy of close-range photogrammetric method is calculated about 7.7 mm as shown in Table 2. The right wall had a mean displacement about 31 mm and the left wall had a mean displacement about 34 mm toward the scoop within two epochs of mea- surements which falls within the normal anticipated range. ...
Similar publications
The high cost of land across urban areas has made the excavation a typical practice to construct multiple underground stories. Various methods have been used to restrain the excavated walls and keep them from a possible collapse, including nailing and anchorage. The excavated wall monitoring, especially during the drilling and restraining operation...
Citations
... In particular, vision-based technologies have the advantage of not only evaluating stability through quantitative analysis but also visually monitoring a site without on-site visits. Various studies have been conducted to measure the behavior of bridges, soil nail walls, retaining walls, and slopes based on 3-D coordinates with images taken from two or more points of view (Jiang and Jauregui 2010, Esmaeili et al. 2013, Oats et al. 2017, Zhao et al. 2018. However, since a stereo camera system requires two or more multiple views, two or more cameras must be installed or one camera must be taken from multiple locations. ...
... In addition, an artificial target (AT) had to be installed to the region of interest (ROI) to track the target on the structure (Jiang and Jauregui 2010, Esmaeili et al. 2013, Lee and Shinozuka 2006, Choi et al. 2011, Feng et al. 2015. However, the AT is not only heterogeneous to the structure, but also it obscures the condition of the structure behind the AT. ...
... In this case, a crucial factor was recognizing the measurement set's geometrical parameters, which determines the absolute accuracy of the derived object model. CRP is also successfully used together with other techniques for remote detection of object geometry [18], such as TLS. An example of such integration in archaeological applications is shown in [19]. ...
In surveying engineering tasks, close-range photogrammetry belongs to leading technology by considering different aspects like the achievable accuracy, availability of hardware and software, accessibility to measured objects, or the economy. Hence, constant studies on photogrammetric data processing are desirable. Especially in industrial applications, the control points for close-range photogrammetry are usually measured using total stations. In the case of smaller items, more precise positions of control points can be obtained by deploying and adjusting a three-dimensional linear network located on the object. This article analyzes the accuracy of the proposed method based on the measurement of the linear network using a professional tape with a precision of ±1 mm. It is shown what accuracy of object feature dimensioning can be obtained based on the proposed innovative network method for photo-point measurement, using only the minimum required number of two stereo-images. The photogrammetric 3D model derived from them and captured with a non-metric camera is characterized by the highest possible precision, which qualifies the presented approach to accurate measurements used in the surveying engineering. The authors prove that the distance between two randomly optional points derived from the 3D model of a dimensioned object is equal to the actual distance measured directly on it with one-millimeter accuracy.
... Therefore, AT could be applied for reliable point identification and matching in the image matching method [41]. In addition, several studies reported that specific types of ATs (i.e., metal plate, black circle centered at a cross, roundel, concentric circles, cross, and speckle patterns) should be used to obtain sufficient intensity variations when a region of interest (ROI) is not sufficient [25,26,42,43]. However, because an object with sufficient strength change can be used as an NT without installing a sheet target, four NTs were assigned in the multiblock experiment to verify the usability, as shown in Figure 2b. ...
Image registration technology is widely applied in various matching methods. In this study, we aim to evaluate the feature matching performance and to find an optimal technique for detecting three types of behaviors—facing displacement, settlement, and combined displacement—in reinforced soil retaining walls (RSWs). For a single block with an artificial target and a multiblock structure with artificial and natural targets, five popular detectors and descriptors—KAZE, SURF, MinEigen, ORB, and BRISK—were used to evaluate the resolution performance. For comparison, the repeatability, matching score, and inlier matching features were analyzed based on the number of extracted and matched features. The axial registration error (ARE) was used to verify the accuracy of the methods by comparing the position between the estimated and real features. The results showed that the KAZE method was the best detector and descriptor for RSWs (block shape target), with the highest probability of successfully matching features. In the multiblock experiment, the block used as a natural target showed similar matching performance to that of the block with an artificial target attached. Therefore, the behaviors of RSW blocks can be analyzed using the KAZE method without installing an artificial target.
... For further details about advances in industrial photogrammetric measurements, the reader is re-ferred to [32] . Moreover, the photogrammetry has been extensively used in the aerospace, civil engineering, wind power blade, and structural monitoring fields [33][34][35][36][37][38] . Recently, researchers have used photogrammetry to investigate the dynamic characteristics of structures [39,40] . ...
Recently, fiber-reinforced composites are widely used in manufacturing of large storage tanks for transportation purposes, thanks to their excellent mechanical and chemical performance, and their good applicability to the shaping of particular geometries. In this contribution, a non-contact 3D optical deformation measurement technique is proposed for monitoring the deformation of carbon-fiber reinforced composite tank subjected to different loading scenarios, which could not be achieved by traditional displacement sensors and resistance strain gauges due to large measuring ranges. This technique is based on the close-range photogrammetry technology, wherein 3D information is extracted from two-dimensional photographs. This is done by positioning artificial reference point markers on the measuring tank before loading, and calculate the 3D coordinates of these markers through analyzing the group photos captured in each loading stage. By tracking and comparing the 3D coordinates of the point markers among different loading stages, the 3D deformation of the tank is obtained. The loading tests comprise both hydrostatic pressure and water-pressurizing tests. The performed in-situ measurements show that the proposed technique can fulfill the efficiency and accuracy requirement of deformation measurement in tank loading tests. This in turn significantly contributes to better understanding the mechanical response at the macroscopic scale, thus improving safety performance.
... In 2013, Esmaeili et al. used close-range target-based photogrammetry for excavated wall displacement measurement. They showed that, using the proposed combined photogrammetric displacement adjustment (CPDA), one could achieve a displacement measurement precision of 8 mm provided photogrammetry targets were installed on the structure [3]. In 2015, Li et al. measured unsaturated soil deformations during triaxial testing using a photogrammetry-based method [4]. ...
... According to the assessment presented in Figure 1, high cost, low rate and difficulty of data acquisition in micro-geodesy and instrumentation methods have led to inefficient or only discontinuous monitoring in such projects. In their research, Esmaeili et al. demonstrated the potentials of photogrammetry for excavated wall displacement measurement [3]. They performed terrestrial imaging by means of photogrammetric targets as base points for displacement measurement on the feature. ...
... In the present research, displacement measurement was performed via combined photogrammetry displacement adjustment (CPDA) method [3]. In the CPDA, combined adjustment is applied on both epochs simultaneously by assuming common observations for base points in both epochs and independent observations at each epoch for the displaced points. ...
The high cost of land across urban areas has made the excavation a typical practice to construct multiple underground stories. Various methods have been used to restrain the excavated walls and keep them from a possible collapse, including nailing and anchorage. The excavated wall monitoring, especially during the drilling and restraining operations, is necessary for preventing the risk of such incidents as an excavated wall collapse. In the present research, an unmanned aerial vehicle (UAV) photogrammetry-based algorithm was proposed for accurate, fast and low-cost monitoring of excavated walls. Different stages of the proposed methodology included design of the UAV photogrammetry network for optimal imaging, local feature extraction from the acquired images, a special optimal matching method and finally, displacement estimation through a combined adjustment method. Results of implementations showed that, using the proposed methodology, one can achieve a precision of ±7 mm in positioning local features on the excavated walls. Moreover, the wall displacement could be measured at an accuracy of ±1 cm. Having high flexibility, easy implementation, low cost and fast pace; the proposed methodology provides an appropriate alternative to micro-geodesic procedures and the use of instrumentations for excavated wall displacement monitoring.
... The factor of safety calculation is now carried by measuring the strains using Fiber Bragg grating (FBG) sensing technology [29]. Esmaili [30] used close range photogrammetry for displacement measurement of soil nail walls. The global stability and sliding stability of soil nail walls against ultimate limit states are also evaluated using reliability analysis based on Monte Carlo simulation technique [31]. ...
This paper aims at the two most common methods used for slope stability analysis. An attempt has been made to bring out the differences in results of reinforced slope stability analysis obtained from SLOPE/W (limit equilibrium based) and PLAXIS 2D (finite element based). The analysis is carried out on two slope angles of 45° and 60°, which are reinforced with nails at three different inclinations of 0°, 15° and 30° respectively. Both the slope angles and all nail inclinations are taken from the horizontal. A comparative study on stability parameters such as factor of safety, critical slip surfaces and nail forces has been carried out. The limit equilibrium method is found to yield higher values of factor of safety in comparison to finite element method. The failure surfaces from both methods are found to vary significantly. Large nail forces are observed by limit equilibrium method for 45° slope with all nail inclinations, whereas for 60° slope angle, finite element method shows an increase in the nail forces. The effect of other parameters like bond length in limit equilibrium, soil–nail interaction and bending stiffness in finite element are also studied.
... For instance, [2] manually marked and referenced corners of prefabricated building façades to recover measurements of façade lengths for quality check purposes. Ref. [106] measured displacement over a soil nailed wall by having a set of retro-reflective targets fixed on the way and then applied a procedure of photogrammetric reconstruction. Ref. [107] surveyed the perimeters and areas in pieces of boat decks with assistance of coded targets for photogrammetric auto recognition and reconstruction. ...
Image-based 3D reconstruction of civil infrastructure is an emerging topic that is gaining significant interest both in the scientific and commercial sectors of the construction industry. Reliable computer vision-based algorithms have become available over the last decade and they can now be applied to solve real-life problems in uncontrolled environments. While a large number of such algorithms have been developed by the computer vision and photogrammetry communities, relatively little work has been done to study their performance in the context of infrastructure. This paper aims to analyze the state-of-the-art in image-based 3D reconstruction and categorize existing algorithms according to different metrics that are important for the given purpose. An ideal solution is portrayed to show what the ultimate goal is. This will be followed by identifying gaps in knowledge and highlighting future research topics that could contribute to the widespread adoption of this technology in the construction industry. Finally, a list of practical constraints that make the 3D reconstruction of infrastructure a challenging task is presented.
Purpose
Displacement measurement in large-scale structures (such as excavation walls) is one of the most important applications of close-range photogrammetry, in which achieving high precision requires extracting and accurately matching local features from convergent images. The purpose of this study is to introduce a new multi-image pointing (MIP) algorithm is introduced based on the characteristics of the geometric model generated from the initial matching. This self-adaptive algorithm is used to correct and improve the accuracy of the extracted positions from local features in the convergent images.
Design/methodology/approach
In this paper, the new MIP algorithm based on the geometric characteristics of the model generated from the initial matching was introduced, which in a self-adaptive way corrected the extracted image coordinates. The unique characteristics of this proposed algorithm were that the position correction was accomplished with the help of continuous interaction between the 3D model coordinates and the image coordinates and that it had the least dependency on the geometric and radiometric nature of the images. After the initial feature extraction and implementation of the MIP algorithm, the image coordinates were ready for use in the displacement measurement process. The combined photogrammetry displacement adjustment (CPDA) algorithm was used for displacement measurement between two epochs. Micro-geodesy, target-based photogrammetry and the proposed MIP methods were used in a displacement measurement project for an excavation wall in the Velenjak area in Tehran, Iran, to evaluate the proposed algorithm performance. According to the results, the measurement accuracy of the point geo-coordinates of 8 mm and the displacement accuracy of 13 mm could be achieved using the MIP algorithm. In addition to the micro-geodesy method, the accuracy of the results was matched by the cracks created behind the project’s wall. Given the maximum allowable displacement limit of 4 cm in this project, the use of the MIP algorithm produced the required accuracy to determine the critical displacement in the project.
Findings
Evaluation of the results demonstrated that the accuracy of 8 mm in determining the position of the points on the feature and the accuracy of 13 mm in the displacement measurement of the excavation walls could be achieved using precise positioning of local features on images using the MIP algorithm.The proposed algorithm can be used in all applications that need to achieve high accuracy in determining the 3D coordinates of local features in close-range photogrammetry.
Originality/value
Some advantages of the proposed MIP photogrammetry algorithm, including the ease of obtaining observations and using local features on the structure in the images rather than installing the artificial targets, make it possible to effectively replace micro-geodesy and instrumentation methods. In addition, the proposed MIP method is superior to the target-based photogrammetric method because it does not need artificial target installation and protection. Moreover, in each photogrammetric application that needs to determine the exact point coordinates on the feature, the proposed algorithm can be very effective in providing the possibility to achieve the required accuracy according to the desired objectives.
Strain measurements are an important tool to evaluate the safety and reliability of large inflatable structures. However, some problems exist when using known measurement techniques in engineering applications. In this work, a method based on digital photogrammetry (DP) and Delaunay triangulation is proposed to measure the strain fields. This method takes into consideration the complex surface profile and geometrical nonlinearity and is suitable for large inflatable structures for which strain fields can be obtained using only photogrammetry. The coordinates of the discrete points on inflatable structure are determined by digital photogrammetry, and then, these points are turned into a triangular mesh using the Delaunay triangulation method. The strains can finally be calculated using the finite element method (FEM) by using the changes in the coordinates. In this work, a bulge test for a circular fabric sheet is performed to verify the validity of the proposed method. The strain fields calculated from this method are compared with results from digital image correlation (DIC). Good agreement is found between the photogrammetry and DIC measurement results. The comparison indicates that the concept of using photogrammetry to measure a strain field is valid. Furthermore, the advantages and disadvantages of the proposed method are discussed.
