Application Of Close-range Photogrammetry Research Articles

A Comparative Study on the Use of Smartphone Cameras in Photogrammetry Applications.

The evaluation of smartphone camera technology for close-range photogrammetry includes assessing captured photos for 3D measurement. In this work, experiments are conducted on many smartphones to study distortion levels and accuracy performance in close-range photogrammetry applications. Analytical methods and specialized digital tools are employed to evaluate the results. OpenCV functions estimate the distortions introduced by the lens. Diagrams, evaluation images, statistical quantities, and indicators are utilized to compare the results among sensors. The accuracy achieved in photogrammetry is examined using the photogrammetric bundle adjustment in a real-world application. In the end, generalized conclusions are drawn regarding this technology's use in close-range photogrammetry applications.

Comparative Evaluation of the Performance of a Mobile Device Camera and a Full-Frame Mirrorless Camera in Close-Range Photogrammetry Applications.

The comparative evaluation of the performance of a mobile device camera and an affordable full-frame mirrorless camera in close-range photogrammetry applications involves assessing the capabilities of these two types of cameras in capturing images for 3D measurement purposes. In this study, experiments are conducted to compare the distortion levels, the accuracy performance, and the image quality of a mobile device camera against a full-frame mirrorless camera when used in close-range photogrammetry applications in various settings. Analytical methodologies and specialized digital tools are used to evaluate the results. In the end, generalized conclusions are drawn for using each technology in close-range photogrammetry applications.

Introducing Unmanned Aerial Vehicles to multi-criteria performance assessment of inspection techniques for port concrete infrastructure

Port infrastructure plays an important role in the economic and social activities of the regions they serve. Pressures induced by the corrosive marine environment and weather conditions, unexpected events associated with climate change, the usually high freight and vehicle loading conditions, the dynamic load of the equipment, and insufficient maintenance and rehabilitation measures that sometimes are not enough to repair an in-service facility, increase the susceptibility of port structures to rapid aging and deterioration. To ensure port infrastructure safety and reliability, and to maintain operational efficiency, port managers are tasked with forming successful inspection schemes for structural condition monitoring. Within this context, identifying the capabilities and prioritizing existing inspection techniques allow for optimizing resources (cost, time, personnel). The issue of performance assessment for commonly used Non-Destructive Testing techniques has received significant research interest. However, state-of-the-art Unmanned Aerial Vehicle techniques have not been previously involved in studies that assess the performance of various inspection techniques. Hence, the present research seeks to introduce Unmanned Aerial Vehicles techniques into multi-criteria performance assessment practices of inspection techniques for port concrete infrastructure. Three Non-Destructive Techniques: a) Infrared Thermography, b) Ground Penetrating Radar, and c) Impact-Echo, are compared to camera-based Unmanned Aerial Vehicle techniques linked to Close Range Photogrammetry applications. A qualitative approach, including a literature review and expert judgment, is applied to acquire data required for Multi-Criteria Decision Analysis practices with the Preference Ranking Organization METHod for Enrichment Evaluation methodology. The ranking output of the applied model is validated with other multi-criteria methods to ensure the robustness of the results. The obtained results for the specific set of criteria will assist decision-makers in selecting the most suitable technique for inspecting surface or sub-surface defects in port concrete infrastructure. Highlights The integration of UAV-driven techniques into current practices for assessing the performance of inspection techniques affects the ranking order The prioritization of the inspection techniques is conducted qualitatively (expert judgment and literature survey) by implementing the PROMETHEE method A camera-based UAV technique improves the practical part of inspections and provides flexibility A camera-based UAV technique is the optimal inspection technique for detecting surface defects, while Impact Echo is preferred for sub-surface defects

Evaluating the Application of Close-Range Photogrammetry in Determining the Horizontal Displacement of High Structural Elements - A Case Study of the Thermal Station at Tishreen University

Evaluating the Application of Close-Range Photogrammetry in Determining the Horizontal Displacement of High Structural Elements - A Case Study of the Thermal Station at Tishreen University

Optical alignment and radiative flux characterization of a multi-source high-flux solar simulator

High-flux solar simulators are research-grade sources of artificial radiation mimicking optical characteristics of concentrating solar systems. They allow for experimental evaluation of high-temperature solar thermal devices and materials under controlled and reproducible conditions. In this study, we demonstrate the application of close-range photogrammetry in tandem with radiometry to optically align radiation modules of a multi-source high-flux solar simulator and to characterize its radiative output. The photogrammetric setup consists of photogrammetry targets, a digital camera and photogrammetry software. The radiometric measurements are conducted using mobile Lambertian targets, a heat flux gauge, and a complementary metal-oxide semi-conductor camera equipped with neutral density filters. An iterative procedure for adjusting lamp positions allows obtaining optical configurations of radiative modules meeting experimental requirements of high and ultra-high temperature solar thermal and thermochemical research. Close-range photogrammetry is demonstrated to be a convenient and effective method to obtain the as-built geometric configuration of the solar simulator setup. We report characteristics of an example radiative module configuration for a subset of six radiation modules. The peak and mean radiative fluxes over a 60-mm diameter flat target located in the focal plane are 3080kWm−2 and 1135kWm−2, respectively. The mean aiming error, defined as the average distance between theoretical and actual aiming points in the focal plane, is reduced from 37.20mm to 4.50mm for the pre- and post-alignment configurations, respectively.

A Mathematical Formulation for Establishing the Relationship of Accuracy and Configuration of Data Acquisition in Close Range Photogrammetry. (Dept. C)

Configuration of data acquisition in close range photogrammetry is defined by (1) the base, which is the distance between the exposure stations of a stereopair, (2) the object distance, which is the perpendicular distance from the center (midfield) of object space to the base, and (3) the convergence of the two camera axes. The accuracy of object space coordinates of points is a function of configuration. A mathematical formulation establishing the relationship of accuracy and configuration is derived and then applied to obtain the optimum configuration, that gives the best accuracy in close range photogrammetry applications. The formulation developed is general and can be applied to calculate the expected accuracy of any given configuration, or to design a configuration that will yield a required accuracy.

Dissipative scaling of step-pool features

This paper focuses on the dissipative similarity of step-pool units at rill, flume and stream scale. This investigation is carried out using recent advances in open channel flow resistance, applications of close-range photogrammetry to rill erosion, available published data on step-pool features in flumes and streams and a new dataset of measurements in fixed bed step-pool rills. A theoretically-based equation for calculating the Darcy-Weisbach friction factor obtained by integration of a power velocity profile is presented. The scale factor Γ of this power velocity profile, which is included in the flow resistance equation, was previously calibrated (Eq. 10) for mobile bed rills with step-pool units. At first, in this investigation an additional test of this flow resistance equation is developed using measurements carried out in fixed bed rills with step-pool features. In particular, the proposed Γ function is tested using the measurements carried out in 63 fixed bed rill reaches incised on a 24 and 26% sloped plot. This test shows that the effect of sediment transport on the flow resistance law can be considered negligible as compared to the effect of the form-induced dissipative mechanisms due to the presence of step-pools structures. Then, using measurements carried out in 61 flume experimental runs and 109 reaches of step-pool streams, this investigation demonstrates that the Γ function for flume and stream conditions can be obtained scaling that (Eq. 10) determined for step-pool rills. The Darcy-Weisbach friction factor values measured in flumes and streams are, on average, higher than those related to rills. Finally, the application of the theoretical equation for calculating the Darcy-Weisbach friction factor for flume and stream conditions requires Γ, estimated by Eq. (10), to be multiplied by a specific scale factor.

3D Imaging of CRP and Ultrasonic Tomography to Detect Decay in a Living Adult Holm Oak (Quercus ilex L.) in Sardinia (Italy)

A field-integrated methodology using 3D ultrasonic tomography supported by close range photogrammetry (CRP) has been developed and evaluated as a tool to detect the presence and patterns of decay forms in a living adult holm oak (Quercus ilex L.) in an urban green area of the city of Cagliari, Sardinia, Italy. Close range photogrammetry was used to compute a high resolution 3D model of the studied tree, texturized with natural colors. Moreover, following the implemented workflow process it was possible to evaluate the deformation pattern of the studied tree over time. In a second step of our integrated approach, and in order to diagnose the state of health of the inner part of the studied tree in a non-invasive way, laboratory and in situ non-invasive ultrasonic techniques were applied. The results of the close range photogrammetry analysis supported the optimal design of the 3D ultrasonic tomography of the living adult holm oak. Ultrasonic tomography is one of the most powerful non-destructive testing techniques for the full-volume inspection of a structure. It produced physical information on the inner structure of the stem of the investigated tree. The results of the study show that the integrated application of close range photogrammetry and 3D ultrasonic tomography is a powerful tool for a highly accurate and objective evaluation of the external and internal decay of trees and for monitoring their conservation states. With the fully integrated approach, the diagnostic process aimed to prevent instability and the failure of trees can be greatly improved.

Application of Close-Range Photogrammetry in Documenting the Location of an Accident

The article analyzes the possibilities of using photogrammetric methods in the inspection of the traffic accident scene by the Police. Experts in the field of road transport often carry out ex post inspections of the traffic accident scene using photogrammetric methods and only then use the results of an inspection carried out by the Police. They do this in order to have a more realistic view of the simulation of an accident during its reconstruction. A 3D model of a car accident site can be a rich source of information and a tool for better imagination what the car accident site looked like. The article presents the procedures of how a police officer should proceed when documenting a traffic accident, what tools for documentation they need in order to be able to create a 3D model of the place of a traffic accident from the prepared photo documentation. The article also presents the accuracy and reliability of this method in relation to additional measurements of dimensions and distances.

Coplanarity Condition for Photogrammetric Simultaneous and Self Calibration Block Adjustments

The well-known collinearity equations are widely employed for the determination of object space coordinates of points during the aerial and close-range photogrammetry applications. On the other hand, the coplanarity equation is applied for analytical relative orientation which is essential for sequential block adjustment procedure. This paper concentrates on deriving mathematical formulation based on coplanarity condition. Softwares utilizing the derived mathematical models have been developed and tested using mathematical photogrammetric data. The effects of random and lens distortion errors on simultaneous and self-calibration block adjustments using the derived mathematical models and collinearity equations have been studied. It was found that the derived mathematical models compensate for the lens distortion errors better than collinearity equations. Furthermore, the accuracy of the results of self-calibration block adjustment using the coplanarity equation is slightly better than those obtained by collinearity equations.

Precise multi-image pointing (MIP) applied on convergence close-range photogrammetry images

PurposeDisplacement 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/approachIn 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.FindingsEvaluation 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/valueSome 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.

Accuracy Assessment of Various Resolutions Digital Cameras For Close Range Photogrammetry Applications

Due to the great evolution in digital commercial cameras, several studies have addressed the using of such cameras in different civil and close-range applications such as 3D models generation. However, previous studies have not discussed a precise relationship between a camera resolution and the accuracy of the models generated based on images of this camera. Therefore the current study aims to evaluate the accuracy of the derived 3D buildings models captured by different resolution cameras. The digital photogrammetric methods were devoted to derive 3D models using the data of various resolution cameras and analyze their accuracies. This investigation involves selecting three different resolution cameras (low, medium and high) and evaluating their calibration accuracies. Assessing the accuracy of the three selected cameras in capturing indoor and outdoor objects; and analyzing the accuracy and the quality of the produced models. The study revealed that:1) It is recommended to use the photos of a high-resolution camera for producing precise 3D models of objects in the outdoor environment especially when the camera/object distance is more than 40 m because the accuracy of the produced models can be precise (RMSE ±10.36mm) with excellent quality; 2) The Low-resolution camera can be utilised to produce adequate 3D models of object in the indoor environment (RMSE ±6.32mm) especially when the camera/object distance is less than 40 m.

CLOSE-RANGE MINI-UAVS PHOTOGRAMMETRY FOR ARCHITECTURE SURVEY

Abstract. The survey of historical façades contains several bottlenecks, mainly related to the geometrical structure, the decorative framework, the presence of natural or artificial obstacles, the environment limitations. Urban context presents additional restrictions, binding by ground acquisition activity and leading to building data loss. The integration of TLS and close-range photogrammetry allows to go over such stuff, not overcoming the shadows effect due to the ground point of view. In the last year the massive use of UAVs in survey activity has permitted to enlarge survey capabilities, reaching a deeper knowledge in the architecture analysis. In the meanwhile, several behaviour rules have been introduced in different countries, regulating the UAVs use in different field, strongly restricting their application in urban areas. Recently very small and light platforms have been presented, which can partially overcome these rules restrictions, opening to very interesting future scenarios. This article presents the application of one of these very small RPAS (less than 300 g), equipped with a low-cost camera, in a close range photogrammetric survey of an historical building façade in Bologna (Italy). The suggested analysis tries to point out the system accuracy and details acquisition capacity. The final aim of the paper is to validate the application of this new platform in an architectonic survey pipeline, widening the future application of close-range photogrammetry in the architecture acquisition process.

USING SMART PHONES FOR DEFORMATIONS MEASUREMENTS OF STRUCTURES

The present work tests the suitability of using the digital cameras of smart phones for close range photogrammetry applications. For this purpose two cameras of smart phones Lumia 535 and Lumia 950 XL were used. The resolutions of the two cameras are 5 and 20 Mpixels respectively. The tests consist of (a) self calibration of the two cameras, (b) the implementation of close-range photogrammetry using the cameras of the two smart phones, theodolite intersection with LST method, and linear variable displacement transducers (LVDTs) for the measurement of vertical deflections, and (c) accuracy of photogrammetric determination of object space coordinates. The results of using Lumia 950 XL are much better than using Lumia 535 and are better or comparable to the results of theodolite intersection with least squares technique (LST). Finally, it can be stated that the digital cameras of smart phones are suitable for close range photogrammetry applications according to accuracy, costs and flexibility.

3D DATA ACQUISITION BASED ON OPENCV FOR CLOSE-RANGE PHOTOGRAMMETRY APPLICATIONS

Abstract. Development of the technology in the area of the cameras, computers and algorithms for 3D the reconstruction of the objects from the images resulted in the increased popularity of the photogrammetry. Algorithms for the 3D model reconstruction are so advanced that almost anyone can make a 3D model of photographed object. The main goal of this paper is to examine the possibility of obtaining 3D data for the purposes of the close-range photogrammetry applications, based on the open source technologies. All steps of obtaining 3D point cloud are covered in this paper. Special attention is given to the camera calibration, for which two-step process of calibration is used. Both, presented algorithm and accuracy of the point cloud are tested by calculating the spatial difference between referent and produced point clouds. During algorithm testing, robustness and swiftness of obtaining 3D data is noted, and certainly usage of this and similar algorithms has a lot of potential in the real-time application. That is the reason why this research can find its application in the architecture, spatial planning, protection of cultural heritage, forensic, mechanical engineering, traffic management, medicine and other sciences.

Characterization of the scour cavity evolution around a complex bridge pier

A study on the time development of local scour around a complex pier was developed using a small-scale model embedded in a sediment bed. A total of 15 laboratorial tests were performed at the Hydraulics Laboratory of the Faculty of Engineering of the University of Porto. The duration of each experiment was previously established to progressively characterize the scour cavity. After each experiment, the flume was gradually emptied to facilitate the application of close-range photogrammetry. The scour depth values resulting from the application of photogrammetry at the pile cap front agree well with the values obtained experimentally. The temporal development of the scour cavity is presented and discussed. Empirical formulas for the scour cavity time development and for the relation of scour depths to scour cavity volumes were obtained. The obtained three-dimensional models can also be used for calibration and validation of numerical models.

Determination method for shear strength parameters of rock-soil mixtures using close-range photogrammetry and 3-D limit equilibrium theory

Using a combination of close-range photogrammetry and three-dimensional(3-D) limit equilibrium theory, a determination method for the shear strength parameters of rock-soil mixture is presented. A close-range photogrammetry method is used for measurement of the 3-D terrain of the experimental target. Auto CAD Lisp and EXCEL VBA are used to perform 3-D limit equilibrium analysis of the stability of sliding mass and perform backanalysis of shear strength parameters. The presented method was used to determine the shear strength parameters of rock-soil mixtures at the Liyuan Hydropower Station. The 3-D terrain of sliding surface could be measured notably well using of closerange photogrammetry. The computed results reveal that the cohesion and friction angle of rock-soil mixtures were 3.15 k Pa and 29.88o for test A, respectively, and 4.43 k Pa and 28.30o for test B, respectively, within the range of shear strength parameters, as determined by field and laboratory tests. The computation of shear strength parameters is influenced by the mesh grid number, especially the cohesion of the rock-soil mixture. The application of close-range photogrammetry can reduce the siteworks and improve the computational efficiency and accuracy.

Close-range photogrammetry applied to the documentation of cultural heritage using telescopic and wide-angle lenses

Close-range photogrammetry is widely used for numerically and graphically representing historical buildings for documentation. Such data can be later used as the base for conservation and restoration processes. The highest precision in point determination in photogrammetry can be achieved using a metric camera, although it is expensive. Recently, many studies have used SLR non-metric cameras, which have the advantage of a self-calibration method and furthermore, are cheaper than the metric camera. In most cases, for close-range photogrammetry applications that use an SLR digital camera, the object is close to the camera (less than 50 m), requiring a wide-angle setting. In our study, the precision achieved is based on a compact camera (Lumix TZ-10) used in building restitution. We experimented with the two extremes in close-range photogrammetry: close object, less than 15 m between the camera lens and to building façade; and distant object, up to 200 m between camera lens and building. In both cases, the precision achieved was suitable for the restitution of the historical buildings: under 1 cm for near objects using a 25-mm wide-angle lens and 3 cm for the distant object using a 280-mm telescopic lens. We achieved remarkable precision in the case of the tele lens, where it is unusual to use the focal length for building restitution in close-range photogrammetry. Nevertheless, a tele lens becomes necessary when it is not possible to place the camera near the object, as in the case of the northern façade of the Alhambra in Granada, Spain.

Systems based on photogrammetry to evaluation of built heritage: tentative guidelines and control parameters

Abstract. Technological innovations based on close-range imaging have arisen. The developments are related with both the advances in mathematical algorithms and acquisition equipment. This evolution allows to acquire data with large and powerful sensors and the fast and efficient processing of data. In general, the preservation of built heritage have applied these technological innovations very successfully in their different areas of intervention, namely, photogrammetry, digital image processing and multispectral image analysis. Furthermore, commercial packages of software and hardware have emerged. Thus, guidelines to best-practice procedures and to validate the results usually obtained should be established. Therefore, simple and easy to understand concepts, even for nonexperts in the field, should relate the characteristics of: (i) objects under study; (ii) acquisition conditions; (iii) methods applied; and (iv) equipment applied. In this scope, the limits of validity of the methods and a comprehensive protocol to achieve the required precision and accuracy for structural analysis is a mandatory task. Application of close-range photogrammetry to build 3D geometric models and for evaluation of displacements are herein presented. Parameters such as distance-to-object, sensor size and focal length, are correlated to the precision and accuracy achieved for displacement in both experimental and on site environment. This paper shows an early stage study. The aim consist in defining simple expressions to estimate the characteristics of the equipment and/or the conditions for image acquisition, depending on the required precision and accuracy. The results will be used to define tentative guidelines considered the all procedure, from image acquisition to final results of coordinates and displacements.

Bed Topography Reconstruction in a Large Amplitude Meandering Flume: Application of Close Range Photogrammetry

Natural rivers are characterized by continuous variations in bed topography, especially along curved reaches. High resolution topographic data are necessary to analyze the mutual interactions between the downstream flow and the cross-stream flow, which determine the distribution of the bed-shear stress along the channel. Because of the difficulty in acquiring good and accurate data in rivers, the major part of studies have been conducted in laboratory flumes. This paper reports on a laboratory study in which the automatic digital photogrammetric survey was applied to derive the high-resolution Digital Surface Model (DSM) of the bed topography in a large amplitude meandering flume. In order to assess the advantages of the procedure, the bed profiles obtained by the DSM have been compared with those obtained using a servo-controlled vertical profiler (PV09) has been operated and discussed.