Digital Close-range Photogrammetry Research Articles

Monitoring of the post-tensile structures camber using the terrestrial close-range photogrammetry

Post-Tensioned Structural Elements (PTSEs) are used in many modern constructions projects as a versatile form of the pre-stressed technique because of the efficiency of the durability properties and the highest resistance if compared with their counterparts. This paper presents an application of using digital measuring techniques in the field of deformation detection by using Digital Close Range Photogrammetry (DCRP), which is one of the most nowadays important sciences that are used in many engineering fields and applications. DCRP techniques have been developed by taking the advantage of the technological advances in the field of optics, laser devices, and the applied mathematical models of computer vision such as the Scale Invariant Feature Transform (SIFT) and the Direct Linear Transform (DLT). The scope of this paper is how to use the digital equipment to achieve the highest possible accuracy in a fraction of 1.00 mm of the PTSE camber monitoring through the commercial digital calibrated camera and Terrestrial Laser Scanner (TLS). The accuracy of the results of the DCRP technique has been proven by a laser total station. The final statistics indicate the deviation of the results compared to the coded designed models of the experimental PTSEs, deviations did not exceed 0.01 mm as a maximum difference.

Utilising non-invasive measurement methods for the inventory of endangered cultural heritage -case study of Iraq

Advanced non-invasive remote sensing techniques, in conjunction with advanced digital technologies designed for the acquisition and comprehensive analysis of extensive datasets, hold substantial promise for significantly augmenting the capacities associated with the documentation of cultural heritage sites. This is especially crucial when it comes to preserving endangered cultural heritage. The main goal of this article was to demonstrate instances of non-invasive approaches used to catalog cultural heritage objectes and locations in Iraq. This investigation showcased a number of examples and employed a variety of contemporary data collection and processing techniques. These included digital close-range photogrammetry, Building Information Modeling (BIM), data from crowdsourced data, and findings derived from Mosul Project. As evident, reality underscores the presence of numerous perils endangering the preservation of tangible cultural heritage sites worldwide. Precious architectural marvels, artistic creations, and natural landmarks are at risk of permanent loss. Therefore, a prompt inventory process, along with the creation of precise digital models, ensures the protection, rescue, and potential reconstruction of these invaluable entities. The instances provided in this article, proved that the application of different digitization methods to Iraq's cultural heritage, can readily serve as a model for other endangered objects and sites.

DIFFERENT DATA JOINING AS A BASIC MODEL FOR HBIM – A CASE PROJECT ST. PATALEIMON IN SKOPJE

Abstract. H-BIM (Heritage Building Information Modelling) is principle and system of use of historic buildings that can be used for the management, reconstruction or renovation and restoration of monuments. It is a set of geometric and descriptive information about a building. In the last decade, several historical objects were documented using modern methods, mainly advanced photogrammetrical and laser technologies, for a wide range of users to get benefits from economically, safety, presentation, and life cycle management of historical buildings. The rapid development in geomatics is possible thanks to advanced technologies of data capturing, sufficient capacity of computer technology and transmission and information networks. The most used technologies are terrestrial laser scanning (TLS), personal laser scanning (PLS) or mobile mapping systems (MMS), terrestrial or aerial drone based close-range digital photogrammetry (using SfM – structure from motion technology and MVS – multi view stereo). Today’s modern advanced technologies allow geometrical and textural data collection within a few centimetres’ accuracy outside and inside infrastructure by various methods of PLS, photogrammetrical SfM and TLS. In terms of object visualisation, VR or AR (virtual or augmented reality) technology is proving to be suitable. The following text discusses the use of geomatics technologies for the creation of H-BIM on the example of a cultural monument in Skopje, North Macedonia, including visualization in virtual reality (VR).

Positional accuracy in close-range photogrammetry through Topography and Geodesy

Computational three-dimensional modelling can be used to reconstruct real-world objects with all their details and conservation conditions. Photogrammetry offers products with accuracy, in addition to the flexibility of execution of simple and complex projects, according to the simplicity and speed in data acquisition. The three-dimensional (3D) and georeferenced modelling allows the documentation of the object that was mapped by means of the location. This paper presents a methodology based on topographic and geodetic techniques with georeferencing applied to three-dimensional modelling of architectural forms with the use of digital close-range photogrammetry. The measurements made on the digital product obtained and the same measurements made using precision topography were compared considering the conversion of coordinates to the same projection and reference systems. Finally, the statistical validation and quantification in terms of the positional accuracy of the final product were performed.

Detection of deformations in reinforced concrete structures using modern surveying techniques

Undoubtedly, the cracks in the reinforced concrete (RC) structures represent a great danger to those structures, and it was necessary to monitor these cracks with high accuracy. In this research, an experiment was done to investigate the use of modern surveying technologies (digital close-range photogrammetry and terrestrial laser scanning) to monitor such deformations. The experiment was done in the field on a real project under construction in a water treatment plant. In this plant, some cracks were found in an existing building and studied using the same proposed modern surveying technologies along with a traditional method (Digital Vernier). The results of the modern surveying methods are compared with those obtained by the traditional methods, proving that the proposed modern methods give accurate and reliable results. One of the most important advantages of these modern methods is that these methods do not require direct contact with the monitored structure. Moreover, these methods provide a three-dimensional model to show the exact details of the reinforced concrete structure.

A Robust and Effective Identification Method for Point-Distributed Coded Targets in Digital Close-Range Photogrammetry

In close-range or unmanned aerial vehicle (UAV) photogrammetry, Schneider concentric circular coded targets (SCTs), which are public, are widely used for image matching and as ground control points. GSI point-distributed coded targets (GCTs), which are only mainly applied in a video-simultaneous triangulation and resection system (V-STARS), are non-public and rarely applied in UAV photogrammetry. In this paper, we present our innovative detailed solution to identify GCTs. First, we analyze the structure of a GCT. Then, a special 2D P2-invariant of five coplanar points derived from cross ratios is adopted in template point registration and identification. Finally, the affine transformation is used for decoding. Experiments indoors—including different viewing angles ranging from 0° to 80° based on 6 mm-diameter GCTs, smaller 3 mm-diameter GCTs, and different sizes mixed—and outdoors with challenging scenes were carried out. Compared with V-STARS, the results show that the proposed method can preserve the robustness and achieves a high accuracy rate in identification when the viewing angle is not larger than 65° through indoor experiments, and the proposed method can achieve approximate or slightly weaker effectiveness than V-STARS on the whole. Finally, we attempted to extend and apply the designed GCTs in UAV photogrammetry for a preliminary experiment. This paper demonstrates that GCTs can be designed, printed, and identified easily through our method. It is expected that the proposed method may be helpful when applied to image matching, camera calibration, camera orientation, or 3D measurements or serving as control points in UAV photogrammetry for scenarios with complex structures in the future.

A comparative experimental study of rill erosion on loess soil and clay loam soil based on a digital close-range photogrammetry technology

Accurately describing rill development is important for building physical process models of soil erosion. The objectives of this study were to investigate the evolution processes of rill erosion morphology, their impacts on runoff and sediment yield, and the relationship between flow hydraulic characteristics and rill erosion dynamic mechanisms on slopes of two soil types, namely, clay loam soil (CLS) and loess soil (LS), under two successive rainfall events at a rainfall intensity of 120 mm h−1. We used digital close range photogrammetry technology to obtain overhead images of two experimental soil bins (5 m long, 1 m wide and 0.5 m deep with a slope gradient of 20°) at 5-minute time intervals to monitor the dynamic processes of rill erosion. The results showed that rill erosion processes exhibited important impacts on sediment and runoff and its hydrodynamic characteristics. Compared with LS, runoff formed and rills developed earlier in the CLS slope. Soil with high clay content was more prone to form rills, but less susceptible to severe soil erosion than LS. Once rills began to develop in LS, soil loss increased and the morphology of rills changed rapidly, as did runoff rate. The flow velocity for the two soils decreased gradually with time and increased along the flow direction. The trend of Froude number (Fr) decreased with time, whereas the Darcy-Weisbach resistance coefficient (f) exhibited an opposite trend. The Reynolds number (Re) of LS increased first and then decreased, while Re of CLS decreased gradually with time. Sediment yield and runoff were positively correlated with f, but significantly negatively correlated with Fr. Moreover, Re was significantly negatively correlated with sediment yield, but not with runoff. These results are of great importance for soil loss prediction.

Inferred oviraptorosaur footprints in the Apenninic Carbonate Platform: New tools for the identification of trackmakers from the Sezze ichnosite (lower-middle Cenomanian; central Italy)

Herein we apply a new approach to the study of theropod footprints with elongated metatarsal traces from the Upper Cretaceous (lower-middle Cenomanian) Sezze ichnosite (Latium, central Italy). In this study, we combine traditional methods and new tools (i.e., close-range digital photogrammetry, sUAS – small Unmanned Aerial System, Principal Component Analysis, and Cluster Analysis) to identify the osteological features of the foot mirrored in the traces, analyse the differential depth of impressions and reconstruct the anatomical structure of the trackmaker foot. The use of close-range photogrammetry allows us to improve the ichnological interpretation and analysis, focusing on anatomical features such as phalangeal pads and claw traces. A dataset consisting of measurements of 66 foot skeletons of theropods and the five best preserved elongated footprints with metatarsal trace was subjected to Principal Component Analysis and Cluster Analysis, to investigate the morphospace occupied by the principal clade of theropods and find the most likely trackmaker among known taxa. The results indicate the clade of Oviraptorosauria as the more consistent producers for the Sezze theropod footprints, opening new questions about the clade dispersal and on the complex paleobiogeography of the Appenninic Carbonate Platform in the Late Cretaceous. The integrated multidisciplinary approach (high-resolution photogrammetry and morphometric analysis) confirms the utility of the new technological methodologies for the ichnological study.

The Dynamic Displacement Monitoring Method Using Unmanned Aerial Vehicles Based on Digital Close-Range Photogrammetry

How to carry out fast and reliable dynamic deformation monitoring of building structures is an important issue for engineers and technicians. Digital close-range photogrammetry technology has the advantages of noncontact, multipoint, and rapid monitoring, and the application of UAVs makes the monitoring task no longer limited by the size of the field, but the current technology can not guarantee the rapid deployment of UAVs in dynamic deformation monitoring, and these methods commonly have higher requirements for image quality, and cannot ensure the stability of accuracy. To this end, we propose a dynamic displacement monitoring method for UAVs based on digital close-range photogrammetry technology and optimize the data processing process for the problem that there is still moving when the UAV hovers. A building with an overhead corridor structure with a large flow of people was selected for the experiment. The experiment used ground digital cameras and drones to monitor separately to compare the monitoring results. The results show that the proposed method is simple and easy to use. The monitoring method can be deployed quickly, which is expected to be applied to emergency monitoring scenarios.

High resolution-optical tomography for in-process layerwise monitoring of a laser-powder bed fusion technology

With the implementation of Laser Powder Bed Fusion technologies for industrial production, the need for in-process monitoring has emerged to ensure stable conditions and the process to succeed. Indeed, despite significant technological advances, the rejected parts are still too high if compared to the more conventional manufacturing techniques. Several defects are known to affect the process, more likely when complex geometries are fabricated. Among these, the production of inclined thin walls without support structures is still critical and, in most cases, geometric distortions are observed on the overhanging surfaces. In order to overcome the above mentioned problems and improve the quality of these critical structures, an high resolution monitoring system based on Optical Tomography (OT) was proposed, called High Resolution-Optical Tomography (HR-OT). It uses a very high-resolution sensor, operating in the visible spectrum of light, on a large area of the surface layers comprising the entire printing platform. This very recent technique, typically applied for the detection of volumetric defects, such as porosity or lack of fusion, was successfully applied, in this paper, for the detection of geometric distortions, allowing to avoid onerous pre-processing phases in the image processing workflow. Specific geometric indexes were selected as monitoring outputs and were used for the construction of appropriate control charts in order to carry out statistical process monitoring. Finally, an off-line 3D reconstruction, by means of digital close range photogrammetry, was used to verify the effectiveness of the proposed monitoring solution when applied for in-process detection of geometric distortions.

ESTIMATIONS OF SEDIMENT TRANSPORT IN A GULLY SYSTEM USING THE MORPHOLOGICAL METHOD

Abstract. Gully erosion seriously threatens farmland and causes soil loss. Estimating sediment transport in a gully system is important for understanding the mechanisms of gully erosion. The morphological method successfully applied in estimating bed-material transport in rivers, for some decades, has yet to be applied to gully erosion. Here, we estimate sediment transport in a gully system using the morphological method. It was applied to a laboratory simulation of a loess catchment. Nine high-resolution Digital Elevation Models (DEMs) were acquired by digital close-range photogrammetry and used to determine morphological change. Mass conservation was used to explain measured morphological change, and to infer the changes in sediment transport in space. The results showed that gully erosion is greater than deposition in the initial stages of gully development. Serious gully erosion occurs in the gully heads or upstream areas, and the erosion and deposition become balance in the downstream area. A large proportion of the total transport was actually concentrated into one main channel. Meanwhile, the active areas (high transport) of sediment transport gradually developed from the downstream to upstream with the gully development.

ANALYSIS OF DATA JOINING FROM DIFFERENT INSTRUMENTS FOR OBJECT MODELLING

Abstract. The aim of this contribution is an analysis of related technologies for data capturing for creating a digital twin of selected construction. As a case project a baroque church was selected. Four technologies were used for object modelling: TLS (terrestrial laser scanning), digital close-range photogrammetry SfM (structure from motion) as a terrestrial and aerial (drone) technology, and PLS (personal mobile laser scanner). It was possible to combine data from drone and terrestrial photogrammetry, the model was compared to TLS and proved to be sufficiently accurate. The data from the PLS were more complex (inside and outside) but did not contain higher parts of the building. However, it suitably complemented the entire interior. The complex model can be made as joined model from all devices and it is suitable for export to virtual reality (VR).

Research on Generalized RQD of Rock Mass Based on 3D Slope Model Established by Digital Close-Range Photogrammetry

The traditional method of obtaining rock quality designation (RQD) cannot fully reflect the anisotropy of the rock mass and thus cannot accurately reflect its quality. In the method of calculating RQD based on three-dimensional network simulation of discontinuities, due to the limited number of samples and low accuracy of discontinuity data obtained by manual contact measurement, a certain deviation in the network is generated based on the data, which has an impact on the calculation result. Taking a typical slope in Dongsheng quarry in Changchun City as an example, in this study, we obtained the discontinuity data of the slope based on digital close-range photogrammetry, which greatly enlarged the sample size of discontinuity data and improved the data quality. Based on the heterogeneity of the rock mass, the optimum threshold of discontinuity spacing was determined when surveying lines were laid parallel to different coordinate axes to calculate the generalized RQD, and the influence of measuring blank areas on the slope caused by vegetation coverage or gravel accumulation was eliminated. The real generalized RQD of the rock mass after eliminating the influence of blank areas was obtained. Experiments showed that, after eliminating the influence of blank areas, the generalized RQD of the slope rock mass more truly represented the complete quality of rock mass and offers a new idea for the quality evaluation of engineering rock mass.

The Techniques of Cultural Heritage: Literature Review

Documentation of cultural heritage is basically a computerized or digital representation of objects contains the realistic portrayal of objects in 2.5 or 3D and other details. It is an unquestionable reality that the most vital thing for transmitting cultural heritage to posterity is a delicate documentation. Up to the present there have been numerous advancements in documentation of cultural heritage through technology development, and contemporary documentation techniques have progressed speedily. In time, current techniques have turned out to be desirable over conventional methods in engineering in the existent state and in assurance of disfigurements and preparation of measured drawing projects of historical edifices. Over the most recent ten years, direct 3D documentation techniques are very well known and that great advancement. Generally several main geomatics approaches are using for documentation , in first approach, image based such as close range photogrammetry, unmanned aerial vehicles, infrared (IR) images, second approach are non-image-based such as conventional measurements, terrestrial laser scanning, and In third approach, many researcher are using hybrid method that companied between different techniques. With ongoing improvements in PC and information technologies, this notable customary method has been change with digital close-range photogrammetry. This new technique offers us new open doors, for example, automatic orientation and procedure of the measurement, create of 3D vector information, advanced ortho-image and digital surface model. Laser scanning is another innovation that lately has turned out to be progressively well known for documentation which gives exceptionally thick 3D points on an object surface with high exactness. Also, the 3D model and ortho-photo can be effortlessly created utilizing produced 3D point clouds and recorded digital pictures. This paper gives an overview about the techniques related with documentation of cultural heritage and the uses of cultural heritage.

Hyper-dimensional Visualization of Cultural Heritage: A Novel Multi-analytical Approach on 3D Pomological Models in the Collection of the University of Milan

Digital close-range photogrammetry allows us to acquire high-fidelity tridimensional models useful to document cultural heritage objects with an impressive level of detail. In addition, this technique carries a strong analytical potentiality, able to gain improved knowledge of cultural objects and their preservation conditions. This project is focused on a comprehensive diagnostic survey using 3D multispectral modeling, high-resolution digital radiography, pulsed thermography, XRF, FT-IR, and FORS spectroscopies to document and characterize from a conservative point of view the poly-material objects that belong to the “Garnier Valletti” pomological collection—a unique collection from both scientific and artistic points of view. The analytical integration of imaging techniques, 3D modeling, and spectroscopic techniques provides information from the surface, sub-surface, and innermost layers of the object, respectively, capturing both accurate morphometric, spectral, and compositional data. The article presents the results obtained on typical poly-material and multilayered objects of this collection for which the combination of the considered techniques provided important data to the technical knowledge of the realization highlighting a particular predictive ability from a conservative point of view.

Documenting Cultural Heritage in very hostile fruition contexts: the synoptic visualization of Giottesque frescoes by Multispectral and 3D Close-range Imaging

Abstract The paper reports the results obtained from the digital survey of Giottesque frescoes in the Archiepiscopal Palace of Milan. Multispectral Imaging and Image Based Modelling techniques have allowed the study, the high-resolution documentation and the virtual reassembly of the fragmented frescoes: the integration of spectral data with RGB ortho-images and 3D models has supported the interpretation of the pictorial cycle by virtually relocating the fresco fragments and evaluating their consistency from a technical, iconographic and art-historical point of view. The experimental results show that the proposed approach has great potential for the documentation of wall paintings preserved in highly hostile contexts of fruition. Due to its versatility and portability in the field, its sub-millimetric accuracy, and the different outputs that can be generated, Close-Range Digital Photogrammetry has proven to be the ideal tool in case of scattered and difficult-to-access data.

Identification of the Potential Critical Slip Surface for Fractured Rock Slope Using the Floyd Algorithm

A rock slope can be characterized by tens of persistent discontinuities. A slope can be massive. The slip surface of the slope is usually easier to expand along with the discontinuities because the shear strength of the discontinuities is substantially lower than that of the rock blocks. Based on this idea, this paper takes a jointed rock slope in Hengqin Island, Zhuhai as an example, and establishes a three-dimensional (3D) model of the studied slope by digital close-range photogrammetry to rapidly interpret 222 fracture parameters. Meanwhile, a new Floyd algorithm for finding the shortest path is developed to realize the critical slip surface identification of the studied slope. Within the 3D fracture network model created using the Monte Carlo method, a sequence of cross-sections is placed. These cross-sections containing fractures are used to search for the shortest paths between the designated shear entrances and exits. For anyone combination of entry point and exit point, the shortest paths corresponding to different cross-sections are different and cluttered. For the sake of safety and convenience, these shortest paths are simplified as a circular arc that is regarded as a potential slip surface. The fracture frequency is used to determine the probability of sliding along a prospective critical slip surface. The potential slip surface through the entrance point (0, 80) and exit point (120, 0) is identified as the final critical slip surface of the slope due to the maximum fracture frequency.

3D pavement macrotexture parameters from close range photogrammetry

ABSTRACT The 3D modelling of pavement surface using digital close-range photogrammetry (CRP) was thoroughly analyzed in this work. The accuracy and precision of the technique were effectively measured. A digital 3D model generated by CRP was compared to the model generated by a laser scanner, considered here as a benchmark for precision. The precision, measured as per cent deviation from a computer-generated model, considered here as the true value, was found to be 3.4% and the accuracy, measured as per cent error, was found to be 4.2%. A study involving 85 locations and 5 different surface types was also conducted to compare the calculated macrotexture parameters to those obtained from the Sand Patch Test and British Pendulum Test (BPT). The creation of a 3D surface model allowed the investigation of parameters other than the averages of height and depth proposed in the current standards. Moreover, the process described in this work can be automated and with proper standardization could be used for management and decision making at the infrastructure's network level. The British pendulum did not show a high correlation to the 3D macrotexture parameters except for the Mean Texture Depth (MTD) calculated from the sand patch itself (R 2 = 59.7%).

New Measurement Methods for Structure Deformation and Objects Exact Dimension Determination

The current rapid development of technologies enables new procedures for deformation and the detecting of construction defects and their modelling and monitoring in BIM. New instruments were developed for fast and sufficiently accurate mapping like personal mobile laser scanners (PLS). In the world of photography, the size of camera sensors is bigger, and the photographs are sharper. The rapid development of computer performance enables automatic and complex calculations, which lead to large sets of detailed 3D data and a high degree of automation. This influences photogrammetry and its methods. The results are more detailed and more accurate. Deformation, defects and exact dimensions (metrology) of different structures or objects can be currently measured by digital close-range photogrammetry. Cracks and cavities are monitored for structure status detection. This is important for planning reconstruction and for financial reasons. For structures like cooling towers, chimneys, or bridges can be created on a 3D model with a high texture resolution for finding and monitoring cracks and cavities. Deformations or defects that were found must be in scale, and measurable for the calculation of the scope of repair work and its price. The generated 3D object model can then be used for further measurements, for the price estimation of renovation, and for the creation of a BIM, in which all processes can be modelled and watched. Deformation can be monitored over time by creating additional models after a defined period. Captured 3D models from different periods can be compared in software like CloudCompare to determine the progress of degradational changes. The trend of the aging of the structure can be traced, which will be helpful for the reasonable planning of reconstruction. Based on the rapid development and miniaturization of measuring devices, new, smaller, easier to use, and more perfect devices are constructed. This also applies to the new group of laser scanners constructed for basic measurement and structure modeling for BIM. Conventional laser scanners can be accurate, but they are relatively large and heavy, difficult to transport and measuring with them is relatively slow (stop and go type). If the project goal is the classic construction, documentation of the object, data transfer to BIM or basic documentation of objects, PLS is the ideal device. Thanks to the development of accurate IMU (inertial measurement unit) and SLAM (simultaneous localization and mapping) technologies, these devices are on the rise. The forthcoming article will inform about the methods of accurate close-range photogrammetry and mobile laser scanning and will show their advantages with specific examples.

Estimating a mathematical formula of soil erosion under the effect of rainfall simulation by digital close range photogrammetry technique

A new design of soil erosion and rainfall simulator is presented at this study as an attempt to deduce a mathematical formula of soil surface erosion phenomenon to describe the behavior of the sandy soil under the rainfall simulation, soil deformation such as the gullies and surface eroding rills are monitored by the Digital Close Range Photogrammetry (DCRP) technique that includes capturing digital images by a smart cellphone camera, and a Terrestrial Laser Scanner (TLS) to digitalize the soil surface as a point cloud data to produce Digital Elevation Models (DEM) with an accuracy reaches 0.10mm with the watershed, color relief, 3D surface model. The results show that the mentioned methods give a typical digital surface feature express especially of using geometrical adjustment that controls the orientation of the digital surface. The SIFT technology of the digital imaging feature detection achieves accurate results despite its small cost, 12% if compared to the TLS method. As a result of the statistical observations, a simple mathematical formula was generated through the DCRP technique that describes the sandy soil behavior under a hybrid technique of rainfall simulation as a relation between the eroding rate and the duration through the different gradient slopes.